bluuebunny/crossref_metadata_2025 huggingface dataset:
Protein-bound phosphorylserine in acid hydrolysates of brain tissue. The determination of [32P]phosphorylserine by ion-exchange chromatography and electrophoresis
Authors: Jones D. A. , Rodnight R.
Published: August 2015

1. Partial acid hydrolysates of proteins derived from cortical slices of guinea-pig brain were divided into two parts and fractionated by ion-exchange chromatography and high-voltage electrophoresis. 2. The apparent yield of protein-bound phosphorylserine by the ion-exchange method was about three times that obtained by electrophoresis. 3. The specific radioactivity of phosphorylserine isolated from 32P-labelled slices by electrophoresis was twice that isolated by chromatography. 4. The discrepancies were found to be due to the presence of unlabelled phosphates of unknown composition in the ‘phosphorylserine’ fraction obtained by the ion-exchange method. 5. Electrical stimulation of slices respiring in the presence of [32P]phosphate increased the specific radioactivity of the total phosphate in the chromatographic ‘phosphorylserine’ fraction by 53±11%, as compared with only 19±5% for the phosphorylserine isolated by electrophoresis.
Synthesis of [1,2-3H2]cholecalciferol and metabolism of [4-14C,1,2-3H2]- and [4-14C,1-3H]-cholecalciferol in rachitic rats and chicks
Authors: Lawson D. E. M. , Pelc B. , Bell P. A. , Wilson P. W. , Kodicek E.
Published: August 2015

[1,2-3H2]Cholecalciferol has been synthesized with a specific radioactivity of 508mCi/mmol by using tristriphenylphosphinerhodium chloride, the homogeneous hydrogen catalyst. With doses of 125ng (5i.u.) of [4-14C,1-3H2]cholecalciferol the tissue distribution in rachitic rats of cholecalciferol and its metabolites (25-hydroxycholecalciferol and peak P material) was similar to that found in chicken with 500ng doses of the double-labelled vitamin. The only exceptions were rat kidney, with a very high concentration of vitamin D, and rat blood, with a higher proportion of peak P material, containing a substance formed from vitamin D with the loss of hydrogen from C-1. Substance P formed from [4-14C,1,2-3H2]cholecalciferol retained 36% of 3H, the amount expected from its distribution between C-1 and C-2, the 3H at C-1 being lost. 25-Hydroxycholecalciferol does not seem to have any specific intracellular localization within the intestine of rachitic chicks. The 3H-deficient substance P was present in the intestine and bone 1h after a dose of vitamin D and 30min after 25-hydroxycholecalciferol. There was very little 25-hydroxycholecalciferol in intestine at any time-interval, but bone and blood continued to take it up over the 8h experimental period. It is suggested that the intestinal 3H-deficient substance P originates from outside this tissue. The polar metabolite found in blood and which has retained its 3H at C-1 is not a precursor of the intestinal 3H-deficient substance P.
Some properties of mitochondria isolated from the flight muscle of the periodical cicada, Magicicada septendecim
Authors: Hansford R. G.
Published: August 2015

Mitochondria from the flight muscle of the periodical cicada oxidize pyruvate and d-glycerol 1-phosphate at rates comparable with those obtained with flight-muscle mitochondria from other insects. The oxidation of d-glycerol 1-phosphate is greatly stimulated by low concentrations of Ca2+. However, oxidative phosphorylation with this substrate is optimum over only a narrow range of Ca2+ concentration, because of the ability of these mitochondria actively to accumulate Ca2+ present at micromolar concentrations. The oxidation of pyruvate via the complete tricarboxylic acid cycle is enhanced by high concentrations of phosphate. When both pyruvate and d-glycerol 1-phosphate are present simultaneously, there is no simple summation of the rates obtained with the substrates singly. Acetyl-l-carnitine, palmitoyl-l-carnitine, glutamate and 2-oxoglutarate are oxidized at rates similar to those obtained with mammalian mitochondria, though lower than those obtained with the two prime substrates. However, no other tricarboxylic acid-cycle intermediates added to the medium were oxidized. From these and other observations it has been concluded that these mitochondria possess a previously undescribed combination of substrate-anion permeases.
Eġġ proteins in cod serum. Natural occurrence and induction by injections of oestradiol 3-benzoate
Authors: Plack P. A. , Pritchard D. J. , Fraser N. W.
Published: August 2015

1. Before the uptake of water that precedes spawning, eggs of cod (Gadus morhua L.) contained 30% dry matter, of which 80% was protein. Some 75% of this protein was soluble in 0.5m-sodium chloride. The major components in the extract were two similar lipoproteins, of molecular weight about 400000, containing 21% lipid, some two-thirds of which was phospholipid, and about 0.5% protein phosphorus. 2. These lipoproteins were identified by immunochemical methods in the serum of female cod with developing ovaries, but not in the serum of male or of immature female fish. 3. The concentrations of egg proteins in the serum of female cod were determined by a serial-dilution double-diffusion immunological method, and were shown to increase with development of the ovaries, reaching a value of about 32mg/ml when the weight of the ovaries was 10% of the weight of the fish. 4. Immature male and female cod were injected intramuscularly with a solution of oestradiol-17β 3-benzoate in oil and the concentration of egg proteins in their serum was measured by the immunodiffusion method. The serum contained no detectable egg proteins before injection of the fish, but 30μg of oestradiol benzoate/kg gave rise to detectable amounts of egg proteins in 10 days, and with 300μg or 1mg of oestradiol benzoate/kg the concentration of egg proteins rose to 32mg/ml. The values for male and female cod were similar and represented about one-half of the total serum protein. 5. With a dose of 1mg of oestradiol benzoate/kg, egg proteins were first detected in the serum 2 days after injection and the concentration increased up to 10 days. 6. Serum samples taken before and 10 days after an injection of 1mg of oestradiol benzoate/kg were fractionated by gel-filtration on Sephadex G-200. The difference curves obtained from fractionation curves after and before injection confirmed the values of the concentrations of egg proteins obtained from the immunodiffusion test and showed that the concentrations of the normal serum components fell by 20–50% of the initial value, the high-molecular-weight globulins showing the most marked fall. 7. Egg proteins were detected in the liver and testes of the injected fish, but not in the ovaries.
Differences in the nature of the interaction of insulin and proinsulin with zinc
Authors: Grant P. T. , Coombs T. L. , Frank B. H.
Published: August 2015

1. The reversible interaction of zinc with pig insulin and proinsulin has been studied at pH7 by equilibrium dialysis (ultrafiltration) and by sedimentation equilibrium and velocity measurements in the ultracentrifuge. Binding values calculated from equilibria, where the ratio of free to bound zinc was varied in the range 0.01:1–10:1, indicated that proinsulin and insulin each contained two main orders of zinc binding with very different affinities for the metal. 2. In equilibria containing low concentrations of free zinc (free: bound ratios of 0.01–0.1:1) both insulin and proinsulin aggregated to form soluble hexamers containing firmly bound zinc (up to 0.284g-atom/monomer) with an apparent intrinsic association constant of 1.9×106m−1. 3. Higher concentrations of zinc (free: bound ratios of 0.1–10.0:1) resulted in a progressive difference in the zinc binding, aggregation and solubility properties of the metal complexes of insulin and proinsulin. At the highest concentration of free zinc, proinsulin bound a total of more than 5.0g-atom/monomer and aggregated to form a mixture of soluble polymers (mainly 5.1S). In contrast, insulin bound a total of only 1.0g-atom/monomer and was almost completely precipitated from solution. 4. These results would indicate that the presence of the peptide segment connecting the insulin moiety in proinsulin does not prevent the firm binding of zinc to the insulin moiety and the formation of hexamers of zinc–proinsulin. At the same time although the connecting peptide contains additional sites of lower affinity for zinc, which should facilitate inter- and intra-molecular cross-linking, the general conformation of the zinc–proinsulin hexamer must preclude the formation of very large and close-packed aggregates that are insoluble in solutions at equilibrium.
The determination of isoniazid and its metabolites acetylisoniazid, monoacetylhydrazine, diacetylhydrazine, isonicotinic acid and isonicotinylglycine in serum and urine
Authors: Ellard G. A. , Gammon P. T. , Wallace S M
Published: August 2015

1. A solvent system was devised for the extraction of isoniazid and its metabolites acetylisoniazid, monoacetylhydrazine, diacetylhydrazine, isonicotinic acid and isonicotinylglycine from serum and urine. 2. Specific chemical and fluorimetric methods were developed for the determination of the extracted isoniazid and acetylisoniazid, and chemical methods for the determination of monoacetylhydrazine, diacetylhydrazine, isonicotinic acid and isonicotinylglycine. 3. When applied to serum, these methods were capable of measuring concentrations of down to about 0.005μg of isoniazid/ml, 0.05μg of acetylisoniazid/ml, 0.2μg of monoacetylhydrazine/ml, 0.2μg of diacetylhydrazine/ml, 0.02μg of isonicotinic acid/ml and 0.1μg of isonicotinylglycine/ml. 4. In urine, these methods were capable of measuring concentrations of down to about 0.05μg of isoniazid/ml, 0.2μg of acetylisoniazid/ml, 1μg of diacetylhydrazine/ml, 0.1μg of isonicotinic acid/ml and 0.2μg of isonicotinylglycine/ml. 5. The stability of these compounds was studied in serum and urine and a method devised to decrease their decomposition in serum.
6-Phosphogluconate dehydrogenase and the assay of uridine diphosphate glucose pyrophosphorylase in the cellular slime mould Dictyostelium discoideum
Authors: Edmundson T. D. , Ashworth J. M.
Published: August 2015

1. 6-Phosphogluconate dehydrogenase activity is present in all morphogenetic stages during cell differentiation in the cellular slime mould. 2. The different ratios of 6-phosphogluconate dehydrogenase/UDP-glucose pyrophosphorylase observed during this process can render spectrophotometric assays of UDP-glucose pyrophosphorylase inaccurate. 3. The disputed occurrence of increases in specific activity of UDP-glucose pyrophosphorylase during cell differentiation in the cellular slime mould is discussed in the light of these observations.
Enzyme synthesis in myxamoebae of the cellular slime mould Dictyostelium discoideum during growth in axenic culture
Authors: Ashworth J. M. , Quance J.
Published: August 2015

1. The specific activities of β-N-acetylglucosaminidase, acid phosphatase, α-mannosidase, β-glucosidase, UDP-glucose pyrophosphorylase and alkaline phosphatase have been determined in myxamoebae of the cellular slime mould Dictyostelium discoideum Ax-2 grown on different media and in different phases of the growth cycle. 2. Variations in enzymic composition occur with changes in growth medium and phase of the growth cycle. 3. The intracellular location of the enzymes studied has been determined. 4. Two enzymes, β-N-acetylglucosaminidase and α-mannosidase, are not only synthesized preferentially as the myxamoebae enter the stationary phase of growth but they are also excreted. The excretion process appears to be specific, because other enzymes that occur in the same intracellular fraction are not excreted.
Zinc transport in rabbit tissues. Some hormonal aspects of the turnover of zinc in female reproductive organs, liver and body fluids
Authors: McIntosh J. E. A. , Lutwak-Mann C.
Published: August 2015

1. To investigate the influence of hormonal conditions upon the kinetics of zinc transport, specific radioactivity of 65Zn was determined in certain tissues and fluids from unmated or pregnant rabbits during the first half of gestation. 2. Compartmental analysis was used to find the simplest mathematical model that simulated satisfactorily tracer behaviour. Models were fitted to experimental results by a numerical procedure using a computer. 3. The kinetics of zinc exchange in most tissues investigated could adequately be described by a three-compartment model, in which total tissue zinc content was divided into a rapidly exchanging pool, with a turnover time of about 1h, and a slowly exchanging pool, the turnover time of which was in liver 15h, in peak-stage corpus luteum 8h, and in the other tissues 30–70h. 4. In rabbit endometrium zinc transport varied with hormonal conditions, the turnover rate being higher in non-pregnant than pregnant endometrium. 5. Uptake of 65Zn by uterine fluid was slow, and in the free-lying embryos (blastocysts) slower still, in keeping with uterine fluid acting as carrier of zinc into the unimplanted embryos. 6. In placental tissue zinc transport varied with gestational stage. Foetal placenta exchanged zinc with blood plasma four times faster than maternal placenta. In foetuses zinc turnover time and flux equalled that of the slow zinc compartment in foetal placenta. 7. Corpus luteum on days 5–6 of gestation showed peak specific radioactivity and zinc flux values, which exceeded those of all other tissues. 8. In liver the slow zinc compartment had a higher rate of turnover than corresponding compartments in tissues other than peak-stage corpus luteum, but no hormone-dependent changes were observed. 9. Zinc uptake by erythrocytes was the slowest of all examined.
Evidence for induced synthesis of an active transport factor for mandelate in Pseudomonas putida
Authors: Higgins S. J. , Mandelstam J.
Published: August 2015

1. At low concentrations of mandelate there is a lag before induction of the mandelate regulon begins at a sub-maximum rate. Cells preinduced with a saturating concentration of inducer do not exhibit this lag when they are transferred to sub-maximum inducer concentrations and are able to maintain a high rate of induction under these conditions. 2. Chloramphenicol was used to show that a protein is synthesized during the lag period that is probably responsible for the maintenance effects observed in batch and continuous cultures. 3. Direct measurements appear to show that induced cells possess an active transport factor for mandelate, sensitive to dinitrophenol, and this is presumably responsible for the maintenance effect. Mandelate is accumulated unchanged against a concentration gradient from media containing low concentrations. At higher external concentrations no accumulation occurs and only a rapid equilibration is noted. Uninduced cells merely equilibrate mandelate.
Purification and properties of arylsulphatase A from chicken brain
Authors: Farooqui A. A. , Bachhawat B. K.
Published: August 2015

1. Chicken brain arylsulphatase A was purified 2000-fold, with overall recovery 14%, by using ammonium sulphate fractionation, ethanol precipitation, Sephadex G-200 gel filtration and DEAE-Sephadex column chromatography. 2. The purified preparation was free from β-glucuronidase, β-galactosidase, acid phosphatase, inorganic pyrophosphatase and adenosine 3′-phosphate 5′-sulphatophosphate sulphohydrolase activities. 3. Polyacrylamide-gel electrophoresis indicated that the purified preparation was not homogeneous. 4. Chicken brain arylsulphatase was markedly inhibited by carbonyl reagents in the presence of traces of Cu2+ in the system. Other metal ions such as Fe2+ and Zn2+, were inactive. 5. Ascorbic acid alone had no effect on enzyme activity but enhances the inhibition by Cu2+. 6. Chicken brain arylsulphatase A resembled arylsulphatase A of other animal species in its kinetic properties such as Km value, anomalous time–activity relationship and the inhibitory effect of phosphate, sulphite and sulphate ions. However, its electrophoretic mobility, behaviour under zinc acetate fractionation and stimulation by Ag+ were similar to arylsulphatase B of other animal species. Thus, this enzyme did not correspond to either arylsulphatase A or arylsulphatase B but properties of both. 7. The purified enzyme preparation can degrade cerebroside 3-sulphate.
Tiglicaciduria in propionicacidaemia
Authors: Nyhan William L. , Ando Toshiyuki , Rasmussen Karsten , Wadlington William , Kilroy Anthony W. , Cottom Dennis , Hull David
Published: August 2015

Tiglic acid, which has not previously been found in human body fluids, was recently detected in the urine of two patients with propionicacidaemia. These patients had a documented defect in the oxidation of propionate. A competition between acrylyl-CoA and tiglyl-CoA for crotonase could explain the accumulation of tiglic acid.
Metabolism of a glutathione conjugate of 2-hydroxyoestradiol-17β in the adult male rat
Authors: Elce John S.
Published: August 2015

Adult male rats with cannulated or ligated bile ducts were given S-(2-hydroxyoestradiol-1-yl)[35S]glutathione, S-(2-hydroxy[6,7-3H2]oestradiol-1-yl)glutathione or S-(2-hydroxyoestradiol-1-yl)[glycine-3H]glutathione by intraperitoneal injection. The recovery of radioactivity in the bile of bile duct-cannulated rats was 33–86% and in the urine of bile duct-ligated rats was 54–105%. Oestrogen thioether derivatives of glutathione, cysteinylglycine, cysteine and N-acetylcysteine were isolated from bile; only the N-acetylcysteine derivatives could be identified in the urine. The steroid moiety was characterized by microchemical tests before and after treatment with Raney nickel: 2-hydroxyoestradiol-17β was released from the glutathione conjugate, and 2-hydroxyoestrone and 2-hydroxyoestrone 3-methyl ether from the other conjugates. From intact rats the recovery of administered radioactivity was about 15% in the urine and 5% in the faeces over a period of several days and the radioactivity appeared to be largely protein-bound. The results demonstrate that injected oestrogen–glutathione conjugate undergoes conversion into N-acetylcysteine derivatives in vivo. Oestrogen–glutathione conjugates formed in the intact rat may be excreted in an apparently non-steroidal, possibly protein-bound form, which would not be detected by current analytical techniques.
The microbial degradation of phenylalkanes. 2-Phenylbutane, 3-phenylpentane, 3-phenyldodecane and 4-phenylheptane
Authors: Baggi G. , Catelani D. , Galli E. , Treccani V.
Published: August 2015

1. Two Pseudomonas strains capable of utilizing 2-phenylbutane, 3-phenylpentane and 4-phenylheptane as the sole carbon and energy source were isolated. 2. Two Nocardia strains capable of utilizing only 3-phenyldodecane as the sole carbon and energy source were isolated. 3. All the isolated strains were unable to grow on the corresponding phenylalkane-p-sulphonates. 4. From liquid cultures of Pseudomonas strains utilizing 2-phenylbutane, 2-(2,3-dihydro-2,3-dihydroxyphenyl)butane was isolated and identified. Evidence for a meta cleavage of the benzene ring was also obtained. 5. From liquid cultures of Pseudomonas strains utilizing 3-phenylpentane, 3-(2,3-dihydro-2,3-dihydroxyphenyl)pentane and 2-hydroxy-7-ethyl-6-oxonona-2,4-dienoic acid were isolated and identified. 6. Evidence for the formation of both a diol and a meta-cleavage compound was obtained from liquid cultures of both Pseudomonas strains utilizing 4-phenylheptane. 7. Liquid cultures of both Nocardia strains utilizing 3-phenyldodecane never formed a diol or a semialdehyde-related compound. 2-Phenylbutyric acid, 3-phenylvaleric acid and 4-phenylhexanoic acid were shown to be present in these cultures.
The acute effect of ethanol on albumin, fibrinogen and transferrin synthesis in the rat
Authors: Jeejeebhoy K. N. , Phillips M. J. , Bruce-Robertson A. , Ho J. , Sodtke U.
Published: August 2015

Decrease of absolute synthesis of albumin and fractional synthesis of transferrin was observed within 3h of orally administering ethanol (4ml/kg) to rats maintained on a 40%-protein diet. In contrast, absolute synthesis of fibrinogen was unaffected. With this ethanol intake, the changes in protein synthesis occurred without significant ultrastructural change in the liver. When the ethanol intake was greater (8ml/kg) ultrastructural disruption was observed. However, both the decrease of plasma protein synthesis and the ultrastructural alterations could be prevented by the simultaneous administration of a mixture of amino acids with the ethanol. The latter findings, not reported hitherto, suggest that ethanol may interfere with hepatic plasma protein synthesis and ultrastructure more through a disturbance of amino acid metabolism than through direct physical damage to the hepatocyte. An Appendix outlines the deconvolutional method used to correct for losses of labelled protein in the period during which measurements were made. The principle may also be applied to labelled plasma urea. The details of the calculations are given in a supplementary paper that has been deposited as Supplementary Publication 50007 at the National Lending Library for Science and Technology, Boston Spa, Yorks. LS23 7BQ, U.K., from whom copies can be obtained on the terms indicated in Biochem. J. (1972) 126, 5.
Lipid metabolism by rat lung in vitro. Utilization of citrate by normal and starved rats
Authors: Scholz Richard W.
Published: August 2015

1. The utilization of [1,5-14C2]citrate by lung slices and cell cytosol preparations, and the activities of liver and lung cytosol citrate-cleavage enzyme (EC 4.1.3.8), l-malate–NAD oxidoreductase (malate dehydrogenase, EC 1.1.1.37) and phosphoenolpyruvate carboxylase (EC 4.1.1.32) were examined in normal and starved rats. 2. Lipogenesis from citrate was decreased by approx. 70% in both the phospholipid and neutral lipid fractions of lung slices from starved rats as compared with fed controls. 3. Incorporation of citrate by lung cytosol preparations into fatty acids was decreased by approx. 35% in the starved rats. The apparent inhibition by avidin of fatty acid synthesis was overcome partially by preincubation of lung cytosol preparations with biotin. These results are consistent with the presence in lung tissue of the malonyl-CoA pathway for fatty acid synthesis. 4. Lung citrate-cleavage enzyme activity decreased in rats that had been starved for 72h whereas malate dehydrogenase and phosphoenolpyruvate carboxylase activities remained unchanged. The results suggest that the pattern of utilization of lipid precursors by rat lung may be altered during various nutritional states.
Transport of amino acids into the oestrogen-primed uterus. Enhancement of the uptake by a preliminary incubation
Authors: Riggs Thomas R. , Pan Mary W.
Published: August 2015

1. Preincubation of the immature rat uterus under physiological conditions was found to increase its subsequent ability to transport α-aminoisobutyric acid, l-proline, l-alanine and 1-aminocyclopentanecarboxylic acid. Uptakes of l-valine, l-phenylalanine and l-leucine were not affected. With α-aminoisobutyric acid, a doubling of the uptake could be obtained after a 3–5h preincubation period. Uteri from oestradiol-primed rats gave increases similar to those found in tissues from untreated animals. In both cases the preincubation increased the Vmax. of α-aminoisobutyric acid uptake but did not affect the Km. 2. The conditions during the preincubation period determined the increase in subsequent uptake of α-aminoisobutyric acid. No increase in uptake was found if the preincubation was carried out at 1°C, in the presence of cyanide or dinitrophenol, under anaerobiosis or with a concentration of puromycin that depressed incorporation of l-leucine into protein by 95%. The puromycin was also shown to prevent the increase in Vmax. normally found after the preincubation period. In addition, no increase was found if Na+was omitted from the preincubation medium. Other inorganic ions had smaller effects. 3. The uptake of α-aminoisobutyric acid by uteri before and after a preincubation period showed the same general patterns of sensitivity to competitive inhibitors, K+, pH, temperature and 2,4-dinitrophenol. 4. The results suggest that the preincubation leads to an increase in a protein component of the ‘A system’ for amino acid transport in the uterus, and that metabolic energy is required for the reactions involved.
The role of mitochondria in modifying calcium-sensitive cytoplasmic metabolic activities. Modification of pyruvate kinase activity
Authors: Meli J. , Bygrave F. L.
Published: August 2015

1. The modification of pyruvate kinase activity in vitro was examined by altering the environmental [Mg2+]/[Ca2+] ratio with EDTA on the one hand and isolated rat liver mitochondria on the other. 2. Controlled additions of Ca2+ and EDTA caused pyruvate kinase activity to be alternately and rapidly switched on and off. 3. By being able to accumulate Ca2+ in preference to Mg2+ rat liver mitochondria were able to alter the [Mg2+]/[Ca2+] ratio in the vicinity of pyruvate kinase and thereby modify the activity of this enzyme. 4. The possible role of mitochondria in modifying pyruvate kinase and other ion-sensitive cytoplasmic enzyme activities is discussed.
Effect of adrenaline on 32P incorporation into rat fat-cell phospholipids
Authors: Stein Janet M. , Hales C. N.
Published: August 2015

1. The phospholipid composition of fat-cells prepared from rat epididymal fat-pad was determined. 2. The incorporation of [32P]Pi into the phospholipids of fat-cells incubated in glucose-free medium and the effect of adrenaline and of α- and β-adrenergic blocking agents, were studied. 3. Incorporation of [32P]Pi into fat-cell phospholipid increased with time; incubation with adrenaline resulted in increased incorporation that was related to the concentration of adrenaline. 4. The pattern of incorporation of [32P]Pi into the individual phospholipids of fat-cells after incubation for 1h was determined; adrenaline (5.4μm) resulted in increased incorporation into phosphatidylcholine. 5. Incubation of fat-cells with propranolol (34μm) and adrenaline (5.4μm) resulted in abolition of adrenaline-stimulated lipolysis; there was a decrease in the specific radioactivity of phosphatidylcholine and an increase in the specific radioactivity of phosphatidylethanolamine, phosphatidic acid, phosphatidylinositol and cardiolipin compared with cells incubated with adrenaline alone. 6. Incubation of fat-cells with phenoxybenzamine (0.1mm) and adrenaline (5.4μm) resulted in stimulation of lipolysis, and in diminished specific radioactivities of phosphatidylcholine, phosphatidic acid, phosphatidylinositol, phosphatidylglycerol and choline plasmalogen compared with cells stimulated with adrenaline alone.
The three-dimensional structure of supercoiled deoxyribonucleic acid in solution. Evidence obtained from the angular distribution of scattered light
Authors: Jolly Douglas J. , Campbell Ailsa M.
Published: August 2015

1. The size and shape of superhelical double-stranded circular DNA from bacteriophage ØX174 were investigated by light-scattering. The molecular weight of the DNA is 3.17×106 and the root-mean-square radius is 103.5nm. 2. The light-scattering envelopes of various theoretical three-dimensional models for such DNA molecules were calculated by repetitive computational techniques, and the results were compared with the experimental findings. 3. It is concluded that the structure of supercoiled DNA containing -12 superhelical turns in buffer of I0.2 corresponds best to one of the more compact models for superhelix structure such as the branched model, and the commonly employed straight interwound superhelix model is incompatible with the experimental results, at the superhelix density found.
The distribution of molecular species of phosphatidylinositol in ox brain and its subcellular fractions
Authors: Luthra M. G. , Sheltawy A.
Published: August 2015

1. The phosphatidylinositol content of white and grey matter of ox cerebral hemispheres did not differ. The phosphatidylinositol from grey matter was slightly enriched in palmitic acid and arachidonic acid, and that from white matter was enriched in eicosatrienoic (C20:3) acid. These regional differences were apparently due to the greater content of myelin in the white matter, since the same tendencies were observed when combined myelinic and non-myelinic subcellular fractions prepared from the cerebral hemispheres were compared. 2. Purified phosphatidylinositol was converted into its triacetylated methylated derivative and resolved to its molecular species by t.l.c. on AgNO3-impregnated silica gel. The tetraenoic molecular species was predominant in phosphatidylinositol from ox cerebral hemispheres, and this feature characterized all the phosphatidylinositol samples extracted from its regions or subcellular fractions. The grey matter was more enriched in the tetraenoic species and the white matter in the trienoic species. 3. The molecular-species composition of phosphatidylinositol from the subcellular fractions of ox cerebral hemispheres was studied. The trienoic species constituted nearly one-fifth of the phosphatidylinositol from two myelinic fractions. ‘Large myelin’ was more enriched in this species than was ‘small myelin’. Both fractions also contained greater concentrations of the dienoic species than the non-myelinic subcellular fractions. The latter fractions, one containing nuclei and the other nerve endings plus mitochondria, were enriched in the monoenoic and tetraenoic species of phosphatidylinositol. The post-mitochondrial supernatant exhibited a pattern of distribution of phosphatidylinositol species intermediate between the myelinic and non-myelinic fractions.
Coproporphyrinogenase activities in extracts of Rhodopseudomonas spheroides and Chromatium strain D
Authors: Tait G. H.
Published: August 2015

1. The anaerobic coproporphyrinogenase activity in an extract of Rhodopseudomonas spheroides is inhibited by 1,10-phenanthroline, αα′-bipyridyl, flavins, 2,4-dinitrophenol and 1,4-naphthaquinone. These compounds have no effect on the aerobic coproporphyrinogenase activity. 2. On removal of small-molecular-weight material from a crude extract, the anaerobic system becomes very unstable; it can be stabilized by adding succinate. Now nicotinamide nucleotides, in addition to Mg2+, ATP and methionine, are required for protoporphyrin to be formed. 3. A mechanism for the anaerobic reaction is proposed, based on the cofactor requirements and the effect of inhibitors. 4. The enzyme responsible for aerobic activity has been partially purified and some of its properties are reported. 5. A crude extract of Chromatium strain D also exhibits coproporphyrinogenase activity under anaerobic conditions in the presence of S-adenosylmethionine or ATP plus methionine. The requirement for other cofactors is variable.
Ring hydroxylation of di-t-butylhydroxytoluene by rat liver microsomal preparations
Authors: Shaw Yon-Shong , Chen Chiadao
Published: August 2015

3,5-Di-t-butylhydroxytoluene (compound I) was converted into 4-hydroperoxy-4-methyl-2,6-di-t-butylcyclohexa-2,5-dienone (compound II), 4-hydroxy-4-methyl-2,6-di-t-butylcyclohexa-2,5-dienone (compound III) and 2,6-di-t-butyl-4-hydroxymethylphenol (compound IV) by rat liver microsomal preparations in the presence of NADPH and air. The oxidation of compound (I) by m-chloroperbenzoic acid also produced the same compounds. These results suggest that hydroperoxide can be an intermediate in aromatic hydroxylation and that biological oxygenations resemble per-acid reactions.
The metabolism of14C-labelled α-methyldopa in normal and hypertensive human subjects
Authors: Au W. Y. W. , Dring L. G. , Grahame-Smith D. G. , Isaac P. , Williams R. T.
Published: August 2015

1. The fate of orally administered14C-labelled l-α-methyldopa has been examined in three normal men and in eight hypertensive patients who responded to the drug and three who did not. 2. The output of14C in the urine in 2 days and in the faeces in 4 days was not very different in any of the subjects. The normals excreted about 40% of the dose in the urine and 60% in the faeces, the responders 52% (range 35–60%) and 45% and the non-responders 42% and 41%. Most of the urinary14C radioactivity was eliminated in 24h after dosing. 3. The main metabolite in the urine was free and conjugated α-methyldopa (normal men, 23% responders, 37% non-responders, 25% of the dose). Free and conjugated 3-O-methyl-α-methyldopa was about 4% in all subjects, total amines (α-methyldopamine and 3-O-methyl-α-methyldopamine) about 6% and ketones (mainly 3,4-dihydroxyphenylacetone) about 3%. 4. The output of α-methyldopamine (2–4% of dose), 3-O-methyl-α-methyldopamine (0.3%) and 3,4-dihydroxyphenylacetone (3–5%) was similar in the one normal and two responders examined. 5. The faecal14C in all subjects was unchanged l-α-methyldopa. 6. In general, the amounts of the metabolites in the urine in normal men and in responding and non-responding patients were quantitatively similar, except in one non-responding patient who converted nearly two-thirds of the absorbed drug into amines and ketones. There appeared to be no correlation between metabolites in the urine and response or lack of response to the drug. 7. In two normal subjects 70–80% of d-α-methyldopa was excreted unchanged in the faeces. Of the absorbed compound most (9–14% of the dose) was excreted as the free and conjugated drug together with a small amount (1–2%) of 3-O-methyl-α-methyldopa. No amines and only traces of ketone were excreted.
The acid and enzymic hydrolysis of O-acetylated sialic acid residues from rabbit Tamm–Horsfall glycoprotein
Authors: Neuberger A. , Ratcliffe Wendy A.
Published: August 2015

Rabbit Tamm–Horsfall glycoprotein and bovine submaxillary glycoprotein were both found to contain sialic acid residues which are released at a slow rate by the standard conditions of acid hydrolysis. These residues are also resistant to neuraminidases from Vibrio cholerae and Clostridium perfringens. This behaviour was attributed to the presence of O-acetylated sialic acid, since the removal of O-acetyl groups by mild alkaline treatment normalized the subsequent release of sialic acid from rabbit Tamm–Horsfall glycoprotein by acid and by enzymic hydrolysis. Determination of the O-acetyl residues in rabbit Tamm–Horsfall glycoprotein indicated that on average two hydroxyl groups of sialic acid are O-acetylated, and these were located on the polyhydroxy side-chain of sialic acid or on C-4 and C-8. These findings confirm the assumption that certain O-acetylated forms of sialic acid are not substrates for bacterial neuraminidases. Several explanations have been suggested to explain the effect of O-acetylation of the side-chain on the rate of acidcatalysed hydrolysis of sialic acid residues.
Phospholipid of the rat glomerular basement membrane in experimental nephrosis
Authors: Fung Kevin K. , Kalant Norman
Published: August 2015

Phospholipids were found to be a constant component of rat glomerular basement-membrane preparations. The concentration fell during preparation of basement membrane by sonication of whole glomeruli, but then remained constant despite continued sonication. The proportions of the individual phospholipids were different from those of whole renal tissue or of isolated glomeruli. The basement-membrane preparations had no (Na++K+)-activated adenosine triphosphatase activity, an enzyme that is bound to plasma membranes. The concentration of lipid P was decreased on exposure in vivo or in vitro to antiserum against basement membrane; 7 days after injection of antiserum there was a change in the phospholipid composition, with a relative increase in phosphatidylcholine and a decrease in sphingomyelin content. The metabolic turnover rate of the lipid P remaining in the membrane was normal, as determined by 32P incorporation. The loss of phospholipid was associated with decreases in the relative concentrations of hydroxyproline, hydroxylysine and glycine, and relative increases in proline, lysine, serine, threonine and valine. Administration of aminonucleoside and daunomycin produced proteinuria but did not cause a decrease in lipid P. Anticollagen and anti-lymphocyte sera that attached to the basement membrane but failed to produce proteinuria, also failed to affect the phospholipid content.
Potassium ion-stimulated and sodium ion-dependent adenosine diphosphate–adenosine triphosphate exchange activity in a kidney microsomal fraction
Authors: Banerjee Shailesh P. , Wong Shirley M. E.
Published: August 2015

1. K+ did not affect the Mg2+-dependent transphosphorylation but markedly increased the Na+-stimulated ADP–ATP exchange rate mediated by a microsomal fraction from guinea-pig kidney. 2. Rb+, Cs+, NH4+ and Li+ were equally effective in stimulating the Na+-dependent ADP–ATP exchange activity. 3. Treatment of the microsomal fraction with N-ethylmaleimide or increased concentrations of Mg2+ prevented stimulation of the Na+-dependent exchange reaction by K+. 4. Ouabain (2.5μm) inhibited ATP hydrolysis by 33% but did not decrease the K+-stimulated Na+-dependent ADP–ATP exchange rate. 5. A possible mechanism for stimulation of exchange activity by K+ is discussed.
The role of the gut flora in the metabolism of cyclamate
Authors: Drasar B. S. , Renwick A. G. , Williams R. T.
Published: August 2015

1. [14C]Cyclamate was not metabolized when incubated with the liver, spleen, kidney or blood of rats of rabbits kept on a cyclamate-containing diet, and that had become converters of cyclamate into cyclohexylamine. 2. [14C]Cyclamate was converted into cyclohexylamine when incubated under anaerobic conditions with the contents of the caecum, colon or rectum or with the faeces of cyclamate-pretreated rats. Similar results were obtained with cyclamate-pretreated rabbits. With cyclamate-pretreated guinea pigs, which did not readily convert cyclamate into cyclohexylamine, the colon contents showed only low activity in this respect. 3. The faeces of a human converter of [14C]cyclamate into cyclohexylamine were also very active, but became less active when cyclamate was removed from his diet. 4. On subculturing the organisms from the contents of the colon and rectum of rats, the ability to convert cyclamate into cyclohexylamine was lost during three subcultures, but the loss of the activity was considerably decreased by subculturing in the presence of cyclamate. 5. Incubation of rat faeces in broths containing cyclamate increased their ability to metabolize cyclamate, but similar treatment of rabbit and human faeces suppressed this activity. 6. When rats are kept on a cyclamate diet the number of clostridia in the faeces increased considerably. In human dietary cyclamate did not appear to alter the counts of various faecal micro-organisms. 7. The gut organisms that appear to develop the ability to convert cyclamate into cyclohexylamine are clostridia in rats, enterobacteria in rabbits and enterococci in man. 8. [14C]Cyclohexylamine injected into the caecum or colon of rats is readily absorbed and excreted in the urine. 9. It appears that on continued intake of cyclamate the gut flora develop the ability to convert cyclamate into cyclohexylamine, which is then absorbed and excreted mainly in the urine, although a small proportion is metabolized to other compounds.
Effects of safrole and isosafrole pretreatment on N- and ring-hydroxylation of 2-acetamidofluorene by the rat and hamster
Authors: Lotlikar Prabhakar D. , Wasserman Michael B.
Published: August 2015

1. The effects of safrole and isosafrole pretreatment on both N- and ring-hydroxylation of 2-acetamidofluorene were studied in male rats and hamsters. 2. Isosafrole (100mg/day per kg body wt.) pretreatment of rats for 3 days did not have any effect on urinary excretion of hydroxy metabolites of 2-acetamidofluorene. However, similar pretreatment with safrole produced increased urinary excretion of N-, 3- and 5-hydroxy derivatives. 3. Similar treatment with these two chemicals for 3 days increased ring-hydroxylation activity by rat liver microsomal material. Increases in N-hydroxylation were much less than those in ring-hydroxylation. Isosafrole was twice as effective as safrole. 4. Increases in hydroxylating activity due to safrole or isosafrole treatment were inhibited by simultaneous administration of ethionine. Similarly, ethionine inhibition was almost completely reversed by the simultaneous administration of methionine. 5. Safrole or isosafrole (0.1mm and 1mm) inhibited 7-hydroxylation activity by liver microsomal material from control rats. At 1mm these two chemicals inhibited both 5- and 7-hydroxylation activity by liver microsomal material from 3-methylcholanthrene-pretreated rats. 3-Hydroxylation activity was not inhibited by 1mm concentrations of these two chemicals. 6. A single injection of safrole (50100 or 200mg/kg body wt.) 24h before assay had no appreciable effect on either N- or ring-hydroxylation activity by hamster liver microsomal material. However, isosafrole (200mg/kg body wt.) treatment inhibited N-, 3- and 5-hydroxylation activities by hamster liver microsomal material; it had no effect on 7-hydroxylation activity.
Mössbauer effect in rubredoxin. Determination of the hyperfine field of the iron in a simple iron–sulphur protein
Authors: Rao K. K. , Evans M. C. W. , Cammack R. , Hall D. O. , Thompson C. L. , Jackson P. J. , Johnson C. E.
Published: August 2015

1. Rubredoxin isolated from the green photosynthetic bacterium Chloropseudomonas ethylica was similar in composition to those from anaerobic fermentative bacteria. Amino acid analysis indicated a minimum molecular weight of 6352 with one iron atom per molecule. 2. The circular-dichroism and electron-paramagnetic-resonance spectra of Ch. ethylica rubredoxin showed many similarities to those of Clostridium pasteurianum, but suggested that there may be subtle differences in the protein conformation about the iron atom. 3. Mössbauer-effect measurements on rubredoxin from Cl. pasteurianum and Ch. ethylica showed that in the oxidized state the iron (high-spin Fe3+) has a hyperfine field of 370±3kG, whereas in the reduced state (high-spin Fe2+) the hyperfine field tensor is anisotropic with a component perpendicular to the symmetry axis of the ion of about −200kG. For the reduced protein the sign of the electric-field gradient is negative, i.e. the ground state of the Fe2+is a [unk] orbital. There is a large non-cubic ligand-field splitting (Δ/k=900°K), and a small spin-orbit splitting (D~+4.4cm-1) of the Fe2+levels. 4. The contributions of core polarization to the hyperfine field in the Fe3+and Fe2+ions are estimated to be −370 and −300kG respectively. 5. The significance of these results in interpretation of the Mössbauer spectra of other iron–sulphur proteins is discussed.
Purine ribonucleotide biosynthesis, interconversion and catabolism in mouse brain in vitro
Authors: Wong Patrick C. L. , Henderson J. Frank
Published: August 2015

The relative rates of the synthetic, interconversion and catabolic reactions of purine metabolism in chopped mouse cerebrum were studied. The rates of incorporation of [14C]adenine and [14C]hypoxanthine into purine ribonucleotides were much less than the potential activities of adenine phosphoribosyltransferase and hypoxanthine phosphoribosyltransferase, and the rates of incorporation were stimulated by the addition of guanosine to the incubation mixture. The availability of ribose phosphates may be a limiting factor for the formation of ribonucleotides from purine bases. The rate of incorporation of [14C]adenosine into purine ribonucleotides was at least seven- to eight-fold higher than that of adenine. The radioactivity in adenine ribonucleotides synthesized from adenine and hypoxanthine was about 100- and ten-fold respectively higher than that in the radioactive guanine ribonucleotides. The conversion of inosinate into guanine ribonucleotides was probably limited by the amount of inosinate available, and the conversion of adenine ribonucleotides into guanine ribonucleotides was probably limited by the activity of adenylate deaminase. The rate of catabolism of [14C]adenosine was low in comparison with its rate of utilization for ribonucleotide synthesis. A fraction of the [14C]hypoxanthine was catabolized to xanthine and urate. [14C]Guanine was completely converted into xanthine, mostly by the guanine deaminase that was released during incubation of chopped mouse cerebrum.
Epoxy derivatives of aromatic polycyclic hydrocarbons. The synthesis of dibenz[a,c]anthracene 10,11-oxide and its metabolism by rat liver preparations
Authors: Sims P.
Published: August 2015

The synthesis of dibenz[a,c]anthracene 10,11-oxide is described. The oxide was unstable and was rapidly decomposed with cold mineral acid into a mixture of 10- and 11- hydroxydibenz[a,c]anthracene. The oxide was converted by rat liver microsomal preparations and homogenates into a product that is probably 10,11-dihydro-10,11-dihydroxydibenz[a,c]anthracene and which was identical with the metabolite formed when dibenz[a,c]anthracene was metabolized by rat liver homogenates. The oxide did not react either chemically or enzymically with GSH. 10,11-Dihydrodibenz[a,c]anthracene and 10,11-dihydrodibenz[a,c]anthracene 12,13-oxide were both metabolized by rat liver preparations into trans-10,11,12,13-tetrahydro-10,11-dihydroxydibenz[a,c] anthracene and the oxide was converted chemically into this dihydroxy compound, and it reacted chemically but not enzymically with GSH. In the alkylation of 4-(p-nitrobenzyl)pyridine, the ‘K-region’ epoxide, dibenz[a,h]anthracene 5,6-oxide, was more active than either dibenz[a,c]anthracene 10,11-oxide or 10,11-dihydrobenz[a,c]anthracene 12,13-oxide.
Environmental effects on the autoxidation of retinol
Authors: Fisher D. , Lichti F. U. , Lucy J. A.
Published: August 2015

1. The behaviour of retinol in aqueous colloidal dispersions has been studied because, if membranes are a physiological site of action of vitamin A, the reactions of colloidal retinol may be relevant to the functions of the vitamin in vivo. 2. Dispersions of retinol in NaCl exhibit characteristic spectral changes, and they consume O2, within minutes of preparation. 3. The maximum rate of O2 uptake is approximately linearly dependent on the concentration of O2. 4. At limiting concentrations of O2, the spectral changes are accelerated by catalase, indicating that H2O2 is one of the reaction products. 5. The autoxidation, which is relatively unaffected by light, has the characteristics of a radical-catalysed reaction. O2 uptake is preceded by an exceptionally short induction period; the reaction is catalysed by Fe2+ ions and is inhibited by diphenylpicrylhydrazyl. 6. The maximum rate of autoxidation, which is less in water or sucrose solution than in saline, depends on the degree of aggregation of retinol molecules induced by cations. 7. In the absence of O2, the cation-induced aggregates exhibit a spectral red-shift, which difference-spectra indicate is caused by formation of a species with λmax. 370–380nm. 8. This species, from which retinol can be quantitatively recovered, is apparently the oxygen-sensitive form of retinol that initiates the rapid autoxidation. 9. The possible biological significance of the production of a highly reactive form of retinol in micellar aggregates is discussed.
Partial purification and properties of rat liver mitochondrial polynucleotide phosphorylase
Authors: See Y. P. , Fitt P. S.
Published: August 2015

1. Polynucleotide phosphorylase was partially purified from the inner membrane of rat liver mitochondria. 2. The partially purified particulate enzyme catalyses phosphorolysis of poly(A), poly(C), poly(U) and RNA to nucleoside diphosphates. 3. It is devoid of nucleoside diphosphate-polymerization activity. 4. Variable amounts of ADP/Pi-exchange activity are associated with the polynucleotide phosphorylase and are probably due to a different enzyme. 5. ADP is the preferred substrate for exchange, and little or no reaction occurs with other nucleoside diphosphates, but ATP/Pi-exchange takes place at one-third the rate observed with ADP. 6. The partially purified enzyme is free from the phosphatases found in the crude mitochondrial inner membrane, but is associated with an endonuclease activity and some adenylate kinase activity; no cytidylate kinase activity analogous to the latter was detectable.