bluuebunny/crossref_metadata_2025 huggingface dataset:
Automated cation-exchange chromatography of peptides at a high sensitivity (0–0.1 absorbance range) (Short Communication)
Authors: Triantaphyllopoulos Eugenie
Published: August 2015

A method is described where leaching of the column resin by pyridine–acetate buffers is minimal and excessive rise of the base-line of the chromatogram is avoided. The method can be used to fractionate peptide mixtures at a concentration of 2–20nmol/component.
Studies on the enzymology of purified preparations of brush border from rabbit kidney
Authors: George S. G. , Kenny A. J.
Published: August 2015

1. A method for the preparation of brush border from rabbit kidneys is described. Contamination by other organelles was checked by electron microscopy and by the assay of marker enzymes and was low. 2. Seven enzymes, all hydrolases, were substantially enriched in the brush-border preparation and are considered to be primarily located in this structure. They are: alkaline phosphatase, maltase, trehalase, aminopeptidase A, aminopeptidase M, γ-glutamyl transpeptidase and a neutral peptidase assayed by its ability to hydrolyse [125I]iodoinsulin B chain. 3. Adenosine triphosphatases were also present in the preparation, but showed lower enrichments. 4. Alkaline phosphatase was the most active phosphatase present in the preparation. The weak hydrolysis of AMP may well have been due to this enzyme rather than a specific 5′-nucleotidase. 5. The two disaccharidases in brush border were distinguished by the relative heat-stability of trehalase compared with that of maltase. 6. The individuality of the four peptidases was established by several means. The neutral peptidase and aminopeptidase M, both of which can attack insulin B chain, differed not only in response to inhibitors and activators but also in the inhibitory effect of a guinea-pig antiserum raised to rabbit aminopeptidase M. This antiserum inhibited both the purified and the brush-border activities of aminopeptidase M. The neutral peptidase and γ-glutamyl transpeptidase were unaffected but aminopeptidase A was weakly inhibited. The characteristic responses to Ca2+ and serine with borate served to distinguish aminopeptidase A and γ-glutamyl transpeptidase from other peptidases. 7. No dipeptidases, tripeptidases or carboxypeptidases were identified as brush-border enzymes. 8. Incubation of brush border with papain released almost all the aminopeptidase M activity but only about half the activities of maltase, γ-glutamyl transpeptidase and aminopeptidase A. No release of alkaline phosphatase, trehalase or the neutral peptidase was observed.
Relative distribution of arylsulphatases A and B in rat liver parenchymal and other cells
Authors: Hook Gary E. R. , Dodgson Kenneth S. , Rose Frederick A. , Worwood Mark
Published: August 2015

The relative activities of arylsulphatases A and B were measured in rat liver parenchymal and non-parenchymal cells, in peritoneal macrophages and in a number of rat tissues. Although absolute values cannot be obtained, it was shown that the arylsulphatase B/arylsulphatase A activity ratio is much higher in non-parenchymal cells than in parenchymal cells. The ratios in adrenals, brain and testis are very similar to each other but differ from those found in spleen, kidney and liver. These ratio variations may be caused by alterations in the activity of the B enzyme rather than the A enzyme. The relatively high B enzyme/A enzyme ratios in all rat tissues explains why the method devised for the independent assay of human arylsulphatases A and B cannot be employed with rat tissues.
The regulation of poly-β-hydroxybutyrate metabolism in Azotobacter beijerinckii
Authors: Senior Peter J. , Dawes Edwin A.
Published: August 2015

1. The enzymes β-ketothiolase, acetoacetyl-CoA reductase, acetoacetate–succinate CoA-transferase (`thiophorase') and d(−)-3-hydroxybutyrate dehydrogenase have been partially purified from crude extracts of glucose-grown nitrogen-fixing batch cultures of Azotobacter beijerinckii. The condensation of acetyl-CoA to acetoacetyl-CoA catalysed by β-ketothiolase is inhibited by CoASH, and the reverse reaction is inhibited by acetoacetyl-CoA. Acetoacetyl-CoA reductase has Km for acetoacetyl-CoA of 1.8μm and is inhibited by acetoacetyl-CoA above 10μm. The enzyme utilizes either NADH or NADPH as electron donor. The second enzyme of poly-β-hydroxybutyrate degradation, d(−)-3-hydroxybutyrate dehydrogenase, is NAD+-specific and is inhibited by NADH, pyruvate and α-oxoglutarate. CoA transferase is inhibited by acetoacetate, the product of hydroxybutyrate oxidation. In continuous cultures poly-β-hydroxybutyrate biosynthesis ceased on relaxation of oxygen-limitation and the rates in situ of oxygen consumption and carbon dioxide evolution of such cultures increased without a concomitant increase in glucose uptake. 2. On the basis of these and other findings a cyclic mechanism for the biosynthesis and degradation of poly-β-hydroxybutyrate is proposed, together with a regulatory scheme suggesting that poly-β-hydroxybutyrate metabolism is controlled by the redox state of the cell and the availability of CoASH, pyruvate and α-oxoglutarate. β-Ketothiolase plays a key role in the regulatory process. Similarities to the pathways of poly-β-hydroxybutyrate biosynthesis and degradation in Hydrogenomonas are discussed.
Fatty acid synthesis in the brown fat and liver of foetal and newborn rabbits (Short Communication)
Authors: Iliffe Jill , Knight Brian L. , Myant Nicolas B.
Published: August 2015

The postnatal fall in fatty acid synthesis in the liver and brown fat of newborn rabbits is accompanied in both tissues by a decrease in the capacities of the enzymes of fatty acid synthesis and an apparent increase in the degree of inhibition of one or more of these enzymes.
The control of the form and function of the ribosomes in androgen-dependent tissues by testosterone
Authors: Mainwaring W. I. P. , Wilce P. A.
Published: August 2015

1. The ribosome content of the rat ventral prostate gland is controlled by the concentrations of circulating androgens and the polyribosomal complement of the total population of ribosomes is acutely dependent on androgenic stimulation. After the administration of testosterone to castrated rats in vivo, there is a pronounced increase in the amounts of heavy (150–240S) polyribosomes. 2. These results are consistent with a pronounced increase in the mRNA and rRNA content of the prostate gland after the administration of testosterone in vivo. 3. From studies conducted both in vitro, the heavy prostate polyribosomes formed after androgenic stimulation are particularly active in protein synthesis. 4. The androgen-stimulated increase in the formation of prostate polyribosomes has a mandatory requirement for sustained RNA and protein synthesis. 5. Since the androgen-mediated increase in prostate polyribosomes may also be suppressed by the concomitant administration of certain anti-androgenic steroids in vivo, the response in polyribosome formation is probably initiated by the binding of a metabolite of testosterone, 5α-dihydrotestosterone, in the prostate gland. 6. The relevance of these findings to the pronounced increase in protein synthesis in androgen-dependent tissues after hormonal stimulation is discussed.
Aberration of porphyrin metabolism in iron-deficient anaemic rats (Short Communication)
Authors: Sharma Dinesh C.
Published: August 2015

Iron-deficient rats excreted greater amounts of 5-aminolaevulinate in urine but the output of porphobilinogen was decreased considerably. In addition, activity of the enzyme 5-aminolaevulinate dehydratase was diminished in bone marrow and liver. The results suggest that in iron deficiency a defect occurs in porphyrin synthesis at the level of porphobilinogen formation.
Control of magnesium–protoporphyrin chelatase activity in Rhodopseudomonas spheroides. Role of light, oxygen, and electron and energy transfer
Authors: Gorchein Abel
Published: August 2015

1. Magnesium–protoporphyrin chelatase activity, previously shown in whole cells of Rhodopseudomonas spheroides, could not be demonstrated in cell-free extracts prepared in different ways, although spheroplasts retained moderate activity. Slight activity was detected also in whole cells of Rhodospirillum rubrum. 2. The effects on the activity of the enzyme of inhibitors of electron and energy transfer were studied in whole cells of Rps. spheroides. Amytal, rotenone, azide and cyanide inhibited at low pO2 in the dark but not under anaerobic conditions in the light. Antimycin A and 2-heptyl-4-hydroxyquinoline N-oxide, as well as uncouplers and oligomycin, inhibited under all environmental conditions. 3. The effects on magnesium chelatase activity of intermediates of the tricarboxylic acid cycle, of thenoyltrifluoroacetone, of a number of artificial electron donors or acceptors, of various quinones and of the oxidation–reduction indicator dyes Benzyl Viologen and Methyl Viologen are described. 4. It was concluded that electron transport between a b-type and a c-type cytochrome as well as associated energy conservation and transformation reactions were essential for activity. There was also a specific requirement for ATP. 5. Exogenous protoporphyrin and magnesium protoporphyrin monomethyl ester were incorporated into bacteriochlorophyll or late precursors by whole cells. 6. Evidence is presented that the insertion of magnesium was the only step inhibited by oxygen in the biosynthetic pathway between protoporphyrin and bacteriochlorophyll.
Biogenesis of mitochondria. The effects of physiological and genetic manipulation of Saccharomyces cerevisiae on the mitochondrial transport systems for tricarboxylate-cycle anions
Authors: Perkins Margaret , Haslam J. M. , Linnane Anthony W.
Published: August 2015

1. Kinetic and equilibrium parameters for the uptake of l-malate, succinate, citrate and α-oxoglutarate by fully functional mitochondria of Saccharomyces cerevisiae were determined. 2. The uptake of l-malate and succinate is mediated by a common carrier, and two other distinct carriers mediate the uptake of citrate and α-oxoglutarate. 3. The properties of the carrier systems for l-malate, succinate and citrate closely resemble those of mammalian mitochondria, but the α-oxoglutarate carrier differs from the mammalian system in minor respects. 4. The composition of the yeast mitochondria was extensively manipulated by (a) anaerobiosis, (b) catabolite repression, (c) inhibition of mitochondrial protein synthesis and (d) elimination of mitochondrial DNA by mutation. 5. The carrier systems for l-malate, succinate, citrate and α-oxoglutarate are essentially similar in the five different types of mitochondria. 6. It is concluded that all the protein components of the carrier systems for l-malate, succinate, citrate and α-oxoglutarate are coded by nuclear genes and synthesized extramitochondrially by cell-sap ribosomes.
The acute action of ammonia on rat brain metabolism in vivo
Authors: Hawkins Richard A. , Miller Alexander L. , Nielsen Richard C. , Veech Richard L.
Published: August 2015

1. Acute NH4+ toxicity was studied by using a new apparatus that removes and freezes the brains of conscious rats within 1s. 2. Brains were removed and frozen 5min after intraperitoneal injection of ammonium acetate (2–3min before the onset of convulsions). Arterial [NH4+] rose from less than 0.01 to 1.74mm at 4–5min. The concentrations of all glycolytic intermediates measured, except glucose 6-phosphate, were increased by the indicated percentage above the control value as follows: glucose (by 41%), fructose 1,6-diphosphate (by 133%), dihydroxyacetone phosphate (by 164%), α-glycerophosphate (by 45%), phosphoenolpyruvate (by 67%) and pyruvate (by 26%). 4. Citrate and α-oxoglutarate concentrations were unchanged and that of malate was increased (by 17%). 5. Adenine nucleotides and Pi concentrations were unchanged but the concentration of creatine phosphate decreased slightly (by 6%). 6. Brain [NH4+] increased from 0.2 to 1.53mm. Net glutamine synthesis occurred at an average rate of 0.33μmol/min per g. 7. The rate of brain glucose utilization was measured in vivo as 0.62μmol/min per g in controls and 0.81μmol/min per g after NH4+ injection. 8. The arteriovenous difference of glucose and O2 increased by 35%. 9. No significant arteriovenous differences of glutamate or glutamine were detected. Thus, although much NH4+ was incorporated into glutamine the latter was not rapidly released from the brain to the circulation. 10. Plasma [K+] increased from 3.3 to 5.4mm. 11. The results indicate that NH4+ stimulates oxidative metabolism but does not interfere with brain energy balance. The increased rate of oxidative metabolism could not be accounted for only on the basis of glutamine synthesis. We suggest that increased extracellular [NH4+] and [K+] decreased the resting transmembrane potential and stimulated Na+,K+-stimulated adenosine triphosphatase activity thus accounting for the increased metabolic rate.
The degradation of intravenously injected chondroitin 4-sulphate in the rat
Authors: Wood Keith M. , Wusteman Frederick S. , Curtis C. Gerald
Published: August 2015

The degradation of chondroitin 4-[35S]sulphate isolated from chick-embryo cartilage was studied in the rat by experiments on free-range animals, on wholly anaesthetized animals with ureter cannulae, by perfusion of isolated liver, by whole-body radioautography and by isolation of liver lysosomes. After injection into rats 68% of the radioactivity was recovered in the urine after 24h, approximately one-half of this being in the form of low-molecular-weight material, chiefly inorganic sulphate. Cannulation experiments demonstrated that the proportion of low-molecular-weight components excreted in the urine increased with time until, after 12h, virtually all was inorganic sulphate. Whole-body radioautography identified the liver as the major site of radioisotope accumulation after injection of labelled polysaccharide. Perfusion through isolated liver indicated that this organ has the ability to metabolize the polymer with the release of low-molecular-weight products, principally inorganic sulphate. Incubation of a lysosomal fraction prepared from rat liver after injection of chondroitin 4-[35S]sulphate gave rise to degradation products of low molecular weight, and experiments in vitro with rat liver lysosomes confirmed that these organelles are capable of the entire degradative process from chondroitin sulphate to free inorganic sulphate.
The absorption of protons with specific amino acids and carbohydrates by yeast
Authors: Seaston A. , Inkson C. , Eddy A. A.
Published: August 2015

1. Proton uptake in the presence of various amino acids was studied in washed yeast suspensions containing deoxyglucose and antimycin to inhibit energy metabolism. A series of mutant strains of Saccharomyces cerevisiae with defective amino acid permeases was used. The fast absorption of glycine, l-citrulline and l-methionine through the general amino acid permease was associated with the uptake of about 2 extra equivalents of protons per mol of amino acid absorbed, whereas the slower absorption of l-methionine, l-proline and, possibly, l-arginine through their specific permeases was associated with about 1 proton equivalent. l-Canavanine and l-lysine were also absorbed with 1–2 equivalents of protons. 2. A strain of Saccharomyces carlsbergensis behaved similarly with these amino acids. 3. Preparations of the latter yeast grown with maltose subsequently absorbed it with 2–3 equivalents of protons. The accelerated rate of proton uptake increased up to a maximum value with the maltose concentration (Km=1.6mm). The uptake of protons was also faster in the presence of α-methylglucoside and sucrose, but not in the presence of glucose, galactose or 2-deoxyglucose. All of these compounds except the last could cause acid formation. The uptake of protons induced by maltose, α-methylglucoside and sucrose was not observed when the yeast was grown with glucose, although acid was then formed both from sucrose and glucose. 4. A strain of Saccharomyces fragilis that both fermented and formed acid from lactose absorbed extra protons in the presence of lactose. 5. The observations show that protons were co-substrates in the systems transporting the amino acids and certain of the carbohydrates.
Respiration-driven proton translocation by yeast mitochondria with differing efficiencies of oxidative phosphorylation
Authors: Downie J. A. , Garland P. B.
Published: August 2015

Measurements were made of the stoicheiometry of proton translocation coupled to respiration in mitochondria from Candida utilis where the number of functional energy-conservation sites between intramitochondrial NADH and oxygen was one in a mutant with a novel oxidase (Downie & Garland, 1972), two in sulphate-deficient cells (Haddock & Garland, 1971) or three in glycerol-limited cells (Light & Garland, 1971). The stoicheiometries of protons translocated per atom of oxygen utilized (i.e. →H+/2e− ratio; Mitchell, 1966) were close to 2.0, 4.0 and 6.0 respectively. Thus by using the same substrate (intramitochondrial NADH) and oxygen throughout, the →H+/2e− ratio is shown to be 2.0 per energy-conservation site when the number of such sites is varied from one to three.
Biosynthesis of serum albumin in rat liver. Evidence for the existence of ‘proalbumin’
Authors: Judah J. D. , Gamble Margaret , Steadman J. H.
Published: August 2015

1. A protein(s) of rat liver (precipitated from soluble extracts of the microsomal fraction by anti-albumin) yields albumin after limited hydrolysis by trypsin. 2. Evidence that the product of limited tryptic hydrolysis is albumin, is based upon ion-exchange chromatography, electrofocusing and peptide `mapping'. 3. The albumin `precursor' is recognized by anti-albumin and is apparently not distinguished from albumin by anti-albumin. 4. A small peptide is liberated from the presumptive albumin precursor during limited tryptic hydrolysis. This peptide is labelled by arginine, but not by leucine, lysine or methionine. 5. These results support our previous suggestion based on kinetic evidence that the albumin-like protein(s), in the anti-albumin precipitate from rat liver, is an albumin precursor.
Optical-rotatory-dispersion studies of compounds related to cholesterol in liposomes and the membranes of erythrocyte ‘ghosts’
Authors: Green Jonathan R. , Edwards Peter A. , Green Colin
Published: August 2015

1. Steroid molecules containing the α,β-unsaturated oxo group in various positions were incorporated with egg phosphatidylcholine into liposomes and into human erythrocyte membranes. 2. The liposomes formed contained 0.3–0.94mol of steroid/mol of phospholipid and the steroids replaced 19–76% of the erythrocyte membrane sterol. 3. The optical rotatory dispersion (o.r.d.) spectra of the steroids in these structures were compared with those obtained in solvents of different polarity. 4. The o.r.d. spectra of cholesta-4,6-dien-3-one and 3-hydroxycholest-3-en-2-one in liposomes resembled those obtained with polar solvents such as ethanol or triethyl phosphate–water (1:1, v/v). 5. The o.r.d. spectra of 3-hydroxycholest-7-en-6-one and 3-hydroxycholest-5-en-7-one in liposomes resembled those obtained with moderately polar solvents such as dioxan. 6. The o.r.d. spectrum of 3-hydroxycholest-8(14)-en-15-one in liposomes resembled those obtained with non-polar solvents such as cyclohexane. 7. 3-Hydroxycholest-3-en-2-one did not exchange with erythrocyte membrane cholesterol, but the other steroids did do so and the o.r.d. spectra of the membranes containing them closely resembled those obtained with liposomes. 8. From the results, the position of sterol molecules with respect to the phospholipid molecules in liposomes and membranes of human erythrocyte ‘ghosts’ can be deduced.
Molecular integrity of chloroplast ribosomal ribonucleic acid
Authors: Leaver Christopher J.
Published: August 2015

The majority of chloroplast 1.1X106-mol.wt. rRNA molecules are nicked at specific points in the polynucleotide chain, the molecules being kept intact at low temperatures by their secondary structure. Conditions that break hydrogen bonds and lead to loss of secondary structure cause dissociation of the molecule.
Reduction of α-oxo carboxyylic acids by pigeon liver ‘malic’ enzyme
Authors: Tang Chung L. , Hsu Robert Y.
Published: August 2015

1. Pigeon liver ‘malic’ enzyme [l-malate–NADP+ oxidoreductase (decarboxylating); EC 1.1.1.40] was shown to catalyse the reductase reaction: [Formula: see text] l-Malate was identified as the reaction product, and was formed in stoicheiometric amount. 2. In addition to oxaloacetate and pyruvate, a number of other α-oxo carboxylic acids were also reduced.
The catalase activity of ferrihaems
Authors: Jones Peter , Robson Terrence , Brown Stanley B.
Published: August 2015

1. The variation of the specific stoicheiometric catalatic activity of proto- and deuteroferrihaem with total ferrihaem concentration has been studied at 25°C over a wide range of pH. For deuteroferrihaem the results imply that only monomeric ferrihaem species contribute significantly to the catalatic activity. Protoferrihaem is more highly dimerized in solution and, in this system, contributions to the catalatic activity from both monomeric and dimeric ferrihaem species were observed. The ratio of the specific activity of protoferrihaem monomer to that of dimer varied from ∼20 at pH7 to 5×104 at pH12.2. 2. The specific activity of protoferrihaem monomer closely resembles that of deuteroferrihaem monomer, both in magnitude and pH-dependence. In both cases the activity is inversely proportional to [H+]. In contrast, the activity of catalase is independent of pH in the range 5–10. At pH13 the activity of ferrihaem monomer becomes equal to the maximal activity of catalase. The results are in good agreement with those reported by Brown et al. (1970b) and provide support for the assumptions upon which this previous analysis relied. 3. Information from the literature concerning the catalatic activity and dimerization of the iron(III) complex of 4,4′,4″,4‴-tetrasulphophthalocyanine (Waldmeier & Sigel, 1971; Sigel et al., 1971) have been re-analysed. The results imply that both the monomeric and dimeric complexes contribute to catalatic activity and these activities closely resemble those of the corresponding protoferrihaem species.
Ribonucleic acid–deoxyribonucleic acid hybridization as a second-order reaction
Authors: Young Bryan D. , Paul John
Published: August 2015

Certain features of RNA–DNA hybridization can be accounted for in terms of second-order-reaction theory. These include the use of annealing kinetics to estimate RNA complexity and the occurrence of approximately linear double-reciprocal plots.
The biosynthesis of plasmodial myosin during starvation of Physarum polycephalum
Authors: White F. Harry , Lascelles June
Published: August 2015

The actomyosin protein complex of Physarum polycephalum was prepared from vegetative and starved plasmodia. The yield of actomyosin per unit wet wt. was the same from both types of plasmodia. Myosin was resolved from the complex by gel filtration and purified by ion-exchange chromatography. The Ca2+-stimulated adenosine triphosphatase activities of myosin preparations from vegetative and starved plasmodia were not appreciably different. Synthesis of myosin de novo was shown to occur during the starvation phase of the life-cycle by the isolation of labelled myosin preparations from plasmodia starved in the presence of [2-14C]glycine. Fractionation of polyacrylamide gels after gel filtration of labelled myosin confirmed the presence of label in the adenosine triphosphatase-active myosin band. It is concluded that during starvation myosin synthesis continues although there is a net loss of approx. 50% of the total protein. Sodium dodecyl sulphate–polyacrylamide-gel electrophoresis of Physarum myosin showed the presence of low-molecular-weight components of the molecule, similar to those of muscle myosins. The content and composition of the free amino acid pool of Physarum was measured at various time-intervals during the vegetative and starvation phases of the life-cycle.
Immunochemical characterization of proteins from mouse liver plasma membranes
Authors: Gurd James W. , Evans W. Howard , Perkins Harold R.
Published: August 2015

1. Antiserum was prepared in rabbits against a purified mouse liver plasma-membrane fraction. 2. The antiserum was made to react with an125I-labelled alkaline-EDTA extract of the plasma membranes, and the immunoprecipitate analysed by polyacrylamide-gel electrophoresis. Seven proteins were immunoprecipitated and a single glycoprotein present in the alkaline-EDTA-soluble fraction was found to be a major component. 3. The alkaline-EDTA-soluble fraction was analysed by two-dimensional immunoelectrophoresis and this procedure indicated the presence of six antigenic components. 4. The plasma membranes were also extracted with 1% deoxycholate–1% Triton X-100; 50% of the protein, 80% of the alkaline phosphodiesterase activity and 30% of the 5′-nucleotidase activity were solubilized. 5. Two-dimensional immunoelectrophoresis of the deoxycholate–Triton X-100 extract indicated the presence of six antigens. 6. The relative distribution of the six antigens among the fractions obtained during the extraction procedure was examined immunoelectrophoretically to provide information on their disposition within the membrane.
Nucleotide sequence analyses of the cytoplasmic 5S ribosomal ribonucleic acid from five species of flowering plants
Authors: Payne P. I. , Corry M. J. , Dyer T. A.
Published: August 2015

Broad-bean 5S rRNA labelled with32P was digested separately with T1 and pancreatic A ribonucleases and the resulting oligonucleotides (20 and 18 respectively) were fractionated by two-dimensional electrophoresis. The oligonucleotides were analysed further and 32 of them have been completely sequenced. They were compared with those of 5S rRNA from dwarf bean, sunflower, tomato and rye. Sequence differences were found at both the 3′- and 5′-termini and at up to nine other positions. Most base substitutions were transitions between C and U. In common with other 5S rRNA species that have been analysed the ends of the molecule in each plant species have complementary sequences.
Cleavage of malyl-coenzyme A into acetyl-coenzyme A and glyoxylate by Pseudomonas AM1 and other C1-unit-utilizing bacteria
Authors: Salem A. R. , Hacking A. J. , Quayle J. R.
Published: August 2015

1. Malyl-CoA lyase was found in high activity in extracts of Pseudomonas AM1, Pseudomonas MA, Pseudomonas MS, Hyphomicrobium X and Methylosinus trichosporium. 2. The enzyme cleaves (2S)-malyl-CoA into equimolar amounts of acetyl-CoA and glyoxylate in the presence of Mg2+. 3. The specific activity of malyl-CoA lyase was several-fold higher in Pseudomonas AM1 when grown on C1 compounds than when grown on C2, C3 or C4 compounds. This suggests that the enzyme plays a specially important role in C1 metabolism. 4. It is suggested that its role in C1 metabolism, in organisms utilizing the serine pathway, is to provide the glyoxylate necessary to sustain operation of this pathway. 5. The activity of malyl-CoA lyase in extracts of Pseudomonas MA, Pseudomonas MS and Hyphomicrobium X is 27–50 times higher than the activity of ATP- and CoA-dependent cleavage of malate, suggesting that the latter activity may be due to coupling of two enzymes, malate thiokinase and malyl-CoA lyase. 6. Methane-grown Pseudomonas methanica and Methylococcus capsulatus, which are not known to use the serine pathway, possess appreciable amounts of malyl-CoA lyase. Instead of being used primarily for carbon assimilation, the enzyme may here serve as a route to glycine during biosynthesis of purines and proteins.
Effect of vitamin A deprivation on the cholesterol side-chain cleavage enzyme activity of testes and ovaries of rats (Short Communication)
Authors: Jayaram M. , Murthy S. K. , Ganguly J.
Published: August 2015

The cholesterol side-chain cleavage enzyme activity is decreased considerably at the mild stage of vitamin A deficiency in rat testes and ovaries and the decrease in activity becomes more pronounced with progress of deficiency. Supplementation of the deficient rats with retinyl acetate, but not retinoic acid, restores the enzyme activity to normal values. The cholesterol side-chain cleavage enzyme of adrenals is not affected by any of the above treatments.
Phosphopyruvate carboxylase induction by l-tryptophan. Effects on synthesis and degradation of the enzyme
Authors: Ballard F. J. , Hopgood M. F.
Published: August 2015

1. The administration of l-tryptophan to fed rats produces a twofold increase in hepatic phosphopyruvate carboxylase activity that represents a comparable increase in enzyme protein. With specific antibody against the enzyme we have shown that the increase in phosphopyruvate carboxylase is partially mediated via an actinomycin D-sensitive increase in enzyme synthesis. 2. In starved animals tryptophan increases the enzyme activity without any change in the relative rate of phosphopyruvate carboxylase synthesis. In this condition degradation of the enzyme is retarded by tryptophan by a mechanism that is not prevented by cycloheximide.
The tritium isotope effect of sn-glycerol 3-phosphate oxidase and the effects of clofenapate and N-(2-benzoyloxyethyl)norfenfluramine on the esterification of glycerol phosphate and dihydroxyacetone phosphate by rat liver mitochondria
Authors: Bowley Mariana , Manning Ray , Brindley David N.
Published: August 2015

1. Owing to a 3H isotope effect, the mitochondrial sn-glycerol 3-phosphate oxidase (EC 1.1.99.5) had a mean activity which was 8.4 times less with sn-[2-3H]-rather than with sn-[1-14C]glycerol 3-phosphate as a substrate. 2. A method for measuring the simultaneous synthesis of lipid from glycerol phosphate and dihydroxyacetone phosphate in rat liver mitochondria is described. 3. The lipid synthesized by rat liver mitochondria from sn-[1-14C]glycerol 3-phosphate was mainly phosphatidate and lysophosphatidate, whereas that synthesized from dihydroxy[1-14C]acetone phosphate was mainly acyldihydroxyacetone phosphate. 4. Additions of NADPH facilitated the conversion of acyldihydroxyacetone phosphate into lysophosphatidate and phosphatidate. 5. Hydrazine (1.4mm) or KCN (1.4mm) inhibited the synthesis of lipids from dihydroxyacetone phosphate but not from glycerol phosphate. 6. Clofenapate (1–2.5mm) inhibited the synthesis of lipids from dihydroxyacetone phosphate but slightly stimulated synthesis from glycerol phosphate. 7. The methanesulphonate of N-(2-benzoyloxyethyl)norfenfluramine, at 0.25–0.75mm, inhibited lipid synthesis from both glycerol phosphate and dihydroxyacetone phosphate.
The potentiation of growth hormone by asparagine and tryptophan
Authors: Ottaway J. H.
Published: August 2015

Asparagine potentiates the growth-promoting effect of bovine growth hormone in rats when injected 3h after the latter, but not earlier. Tryptophan potentiates only when injected simultaneously with the hormone. The possible mode of action of growth hormone, and the likelihood that asparagine is a limiting factor in the growth of animals, are discussed.
The degradation of l-histidine in the rat. The formation of imidazolylpyruvate, imidazolyl-lactate and imidazolylpropionate
Authors: Emes Alan V. , Hassall Harold
Published: August 2015

1. Soluble and mitochondrial forms of histidine–pyruvate aminotransferase were separated from rat liver preparations by chromatography on DEAE-cellulose. 2. These enzymes were characterized with respect to substrate specificity, substrate affinity, pH optimum, stability and molecular weight by chromatography on Sephadex G-200. 3. Each enzyme has a relatively broad specificity showing significant activity towards l-phenylalanine and l-tyrosine and catalysing transamination with a number of monocarboxylic 2-oxo acids. 2-Oxoglutarate is not a substrate for either enzyme. 4. The molecular weights of the two enzymes, by chromatography on Sephadex G-200, are in the range 130000–150000. 5. The formation in vitro of imidazolyl-lactate from imidazolylpyruvate and NADH was demonstrated by using liver preparations. 6. From a study of imidazolyl-lactate–NAD+oxidoreductase activity after electrophoresis of liver preparations on polyacrylamide gel, and from an examination of the activity of l-lactate–NAD+oxidoreductase (EC 1.1.1.27) towards imidazolylpyruvate, it is concluded that this latter enzyme is responsible for the formation of imidazolyl-lactate in the liver. 7. Preparations of bacteria obtained from rat faeces form imidazolylpropionate from l-histidine and urocanate without further subculture. The amount of imidazolylpropionate formed is increased under anaerobic conditions and more so in an atmosphere of H2. It is suggested that the gut flora of the rat contribute largely, if not exclusively, to the formation of imidazolylpropionate normally found in the urine.
Proton translocation coupled to quinol oxidation in ox heart mitochondria
Authors: Lawford Hugh G. , Garland Peter B.
Published: August 2015

The suitability of ubiquinol1 and duroquinol as pulse reductants for initiating respirationdriven proton translocation by aerobic ox heart mitochondria was investigated. At 25°C the Vmax. for oxidation was close to 280nmol of quinol oxidized/min per mg of protein, and the Km values were 8μm for ubiquinol1 and 28μm for duroquinol. Pulses of ubiquinol1 and duroquinol were rapidly and completely oxidized by aerobic mitochondria with a simultaneous acidification of the suspending medium as detected with a glass electrode. The →H+/2e−ratios (Mitchell, 1966) calculated from the observed extent of acidification and the amount of quinol added were 3.62 for ubiquinol1 and 2.98 for duroquinol. These values are underestimates of the true value owing to proton back-flow across the membrane. An analogue computer model was used to correct the observed extent of respirationdriven acidification for proton back-flow. The corrected →H+/2e−values were 4.01 for ubiquinol and 3.86 for duroquinol oxidation. Attempts to measure the rate of proton translocation with a pH-measuring system with a response time of 0.4s were not entirely satisfactory, owing to the relative slowness of the electrode response. Nevertheless the maximal rate of proton generation during ubiquinol1 oxidation was about 1200ng-ions of H+/min per mg of mitochondrial protein. It is concluded, contrarily to Chance & Mela (1967), that mitochondria exhibit a proton-translocating ubiquinol oxidase activity with a →H+/2e−ratio of 4.0.
Vitamin A economy of the developing chick embryo and of the freshly hatched chick
Authors: Joshi P. S. , Mathur S. N. , Murthy S. K. , Ganguly J.
Published: August 2015

1. The changes in the net amounts of retinol, retinyl esters and retinal in both the developing chick embryo and the newly hatched chick were investigated. The embryo requires about 68nmol of the vitamin for its growth, whereas the baby chick requires about 108nmol during the first 7 days after hatching. 2. Retinal was present in the egg in fairly high concentrations at the beginning of the incubation but it virtually disappeared from the extra-embryonic tissue after day 17 of incubation. It was not found in the liver of the embryo or of the newly hatched chick up until day 7.
Age-dependent arylsulphatase and sulphotransferase activities in the southern armyworm: a possible insect endocrine regulatory mechanism? (Short Communication)
Authors: Yang Raymond S. H. , Pelliccia Joseph G. , Wilkinson C. F.
Published: August 2015

Arylsulphate and sulphotransferase activities were determined during the late larval development of the southern armyworm. Arylsulphatase titre attains a maximum during the moult and is at a minimum between moults. Sulphotransferase titre appeared to follow the inverse course. A possible enzymic regulatory mechanism for insect steroid hormones is discussed.
Molecular weight as a factor in the excretion of monoquaternary ammonium cations in the bile of the rat, rabbit and guinea pig
Authors: Hughes Robin D. , Millburn Peter , Williams R. Tecwyn
Published: August 2015

1. The excretion in the bile and urine of intraperitoneally injected14C-labelled monoquaternary ammonium or pyridinium cations was measured in bile-duct-cannulated rats (ten compounds) and in guinea pigs and rabbits (six compounds). 2. Seven of these, namely N-methylpyridinium, tetraethylammonium, trimethylphenylammonium, diethylmethylphenylammonium, methylphenyldipropylammonium, dibenzyldimethylammonium and tribenzylmethylammonium, were excreted largely unchanged in the bile and urine. 3. 3-Hydroxyphenyltrimethylammonium, 3-bromo-N-methylpyridinium and cetyltrimethylammonium were metabolized to an appreciable extent in the rat. 4. In intact rats intraperitoneally injected trimethylphenylammonium (mol.wt. 136) was excreted mainly in the urine, dibenzyldimethylammonium (mol.wt. 226) was excreted in roughly equal amounts in the urine and faeces, and tribenzylmethylammonium (mol.wt. 302) was excreted mainly in the faeces. The faecal excretion of these compounds corresponded to their biliary excretion in bile-duct-cannulated rats. About 3–4% of tribenzyl[14C]methylammonium was eliminated as14CO2. 5. In rats the extent of biliary excretion of four cations with molecular weights in the range 94–164 was less than 10% of the dose, whereas that of five cations with molecular weights 173–302 was greater than 10%. These results and other data from the literature suggested that the molecular weight needed for the biliary excretion of such cations to an extent of 10% or more of the dose was about 200±50. Studies with six cations in guinea pigs and rabbits suggest that this value applies also to these species. 6. The results suggest that the threshold molecular weight for the appreciable (>10%) biliary excretion of monoquaternary cations is different from that for anions (Millburn et al., 1967a; Hirom et al., 1972b). With rats, guinea pigs and rabbits, no significant species difference was noted, whereas with anions there is a marked species difference.
The role of protein kinase activation in the control of steroidogenesis by adrenocorticotrophic hormone in the adrenal cortex
Authors: Richardson Malcolm C. , Schulster Dennis
Published: August 2015

A method has been developed for investigation of the effect of adrenocorticotrophic hormone (ACTH) on the state of activation of a cyclic AMP-dependent protein kinase within cells of the adrenal cortex. Enzyme activity was measured in terms of the quantity of32P transferred from [γ-32P]ATP to histone under conditions in which bound cyclic AMP did not dissociate from the regulatory subunit of the protein kinase ACTH (1×10-2i.u./ml) caused a rapid and complete activation of the cyclic AMP-dependent protein kinase activity within 2min of hormone addition to the isolated cells. In response to a range of ACTH concentrations a sigmoid log dose–response curve for protein kinase activation was obtained, with half-maximal stimulation attained at about 1×10-3i.u./ml. However, some low doses of ACTH that elicited a marked (but submaximal) steroidogenic response failed to cause a clear stimulation of protein kinase activity in isolated adrenal cells. Theophylline (2mm) potentiated the effect of ACTH on protein kinase activity. The results implicate an important role for protein kinase in ACTH action on the adrenocortical cell.
Preparation of some immobilized linked enzyme systems and their use in the automated determination of disaccharides
Authors: Inman D. J. , Hornby W. E.
Published: August 2015

1. Glucose oxidase (EC 1.1.3.4), amyloglucosidase (EC 3.2.1.3), invertase (EC 3.2.1.26) and β-galactosidase (EC 3.2.1.23) were covalently attached via glutaraldehyde to the inside surface of nylon tube. 2. The linked enzyme system, comprising invertase immobilized within a nylon tube acting in series with glucose oxidase immobilized in a similar way, was used for the automated determination of sucrose. 3. The linked enzyme system, comprising β-galactosidase immobilized within a nylon tube acting in series with glucose oxidase immobilized in a similar way, was used for the automated determination of lactose. 4. The linked enzyme system, comprising amyloglucosidase immobilized within a nylon tube acting in series with glucose oxidase immobilized in a similar way, was used for the automated determination of maltose. 5. Mixtures of glucose oxidase and amyloglucosidase were immobilized within the same piece of nylon tube and used for the automated determination of maltose. 6. Mixtures of glucose oxidase and invertase were immobilized within the same piece of nylon tube and used for the automated determination of sucrose.
Inhibition of enzymes by metal ion-chelating reagents. Theory and new graphical methods of study
Authors: Bardsley William G. , Childs Robert E.
Published: August 2015

1. The mechanism of inhibition of enzymes by metal ion-chelating reagents is discussed and equations derived. 2. Two distinct mechanisms are postulated and graphical methods are given for differentiating between them. 3. Where the metal ion is actually removed from the enzyme to form a co-ordination complex in solution, a procedure is described for obtaining the stability constant for metal–enzyme interaction, the number of metal ions involved and the stoicheiometry of metal ion–ligand interaction.
Chymotryptic inhibitor I from potatoes. The amino acid sequence of subunit A*
Authors: Richardson M.
Published: August 2015

The amino acid sequence of subunit A of the potato chymotryptic inhibitor I was determined. The sequence was deduced from analysis of fragments and peptides derived from the protein by cleavage with cyanogen bromide, N-bromosuccinimide and dilute acid, and by digestion with trypsin, thermolysin, pepsin and papain. The molecule consists of a single polypeptide chain of 84 residues, which contains two homologous regions each of 13 amino acids. The protein does not appear to be homologous with any other known proteinase inhibitors.
Mössbauer spectroscopy of the nitrogenase proteins from Klebsiella pneumoniae. Structural assignments and mechanistic conclusions
Authors: Smith Barry E. , Lang George
Published: August 2015

The Mo–Fe protein and the Fe protein which together constitute the nitrogenase of Klebsiella pneumoniae were prepared from bacteria grown in 57Fe-enriched medium. The Mössbauer spectrum of the Mo–Fe protein, as isolated in the presence of Na2S2O4, showed that the protein contained three iron species, called M4, M5 and M6. The area of the spectrum associated with species M4, with δ=0.65mm/s and ΔE=3.05mm/s at 4.2°K, corresponded to two iron atoms/molecule of protein and it is interpreted as being due to a high-spin ferrous, spin-coupled pair of iron atoms. The iron atoms of species M4 may be involved in the quaternary structure of the protein. Species M5, with δ=0.61mm/s and ΔE=0.83mm/s at 77°K, corresponded to eight iron atoms/molecule of protein and is interpreted as being due to Fe4S4 or Fe2S2 low-spin ferrous iron clusters. Species M6, with δ=0.37mm/s and ΔE=0.71mm/s at 77°K, also corresponded to eight iron atoms/molecule of protein and, at 4.2°K, became a broad shallow absorption, characteristic of magnetic hyperfine interaction. Oxidation of the Mo–Fe protein with the redox dye Lauth's Violet did not affect the activity of the protein but changed species M4, M5 and M6 into the species M1 (δ=0.37mm/s, ΔE=0.75mm/s at 77°K, broad magnetic component at 4.2°K) and M2 (δ=0.35mm/s, ΔE=0.9mm/s at 4.2°K). In the presence of the Fe protein, Na2S2O4, ATP and Mg2+, the M6 component of the Mo–Fe protein was replaced by species M7 with δ=0.46mm/s, ΔE=1.04mm/s at 4.2°K. The change in Mössbauer parameters associated with the M6 → M7 transformation was very similar to the change observed on reduction of the high-potential Fe protein from Chromatium vinosum. In contrast, Na2S2O4-reduced Fe protein contained only one type of iron cluster (F4). Species F4 had δ=0.50mm/s, ΔE=0.9mm/s at 195°K, and at 4.2°K broadened in a manner characteristic of a magnetic hyperfine interaction, associated with half-integral spin, equally distributed over all four atoms of the Fe protein. The Mössbauer spectra of the Mo–Fe and the Fe protein under argon were unaffected by the reducible substrates N2 and C2H2 and the inhibitor CO in the presence of ATP, Mg2+ and Na2S2O4. A number of Mössbauer spectral species associated with inactivated Mo–Fe and Fe proteins are described and discussed.
Reactivity of the active-centre lysine residue of rabbit muscle aldolase
Authors: Anderson Peter J. , Kaplan Harvey
Published: August 2015

The method of competitive labelling with [3H]acetic anhydride as the labelling reagent was used to determine the properties of the active-centre lysine residue of rabbit muscle aldolase. This residue is much less reactive than a normal exposed lysine residue towards this reagent, and its reactive properties did not parallel the pH–activity profile for aldolase. At higher pH values it became reactive, but this was shown to be due to disruption of the enzyme structure. The binding of the competitive inhibitor phosphate did not alter the reactive properties. It is concluded that the active-centre lysine has an apparent pKa greater than 11.5 and probably is made nucleophilic during the catalytic process, perhaps by proton abstraction.
Chemical and biochemical studies on 18-hydroxyoestrone
Authors: Findlay John K. , Siekmann Lothar , Breuer Heinz
Published: August 2015

1. 18-Hydroxyoestrone was reduced by NaBH4 in methanol, giving 18-hydroxyoestradiol-17α and 18-hydroxyoestradiol-17β in the ratio 3:7. 2. Treatment of 18-hydroxyoestrone with a strong alkali yielded 18-noroestrone; however, the 18-hydroxyoestradiols did not undergo transformation to their respective 18-nor derivatives. 3. All the 18-hydroxylated oestrogens were stable under acid conditions. They formed Kober chromogens: the chromogenicity of 18-hydroxyoestrone was only one-third that of the 18-hydroxyoestradiols and oestriol. 4. Paper-, thin-layer- and gas–liquid-chromatographic systems for the characterization of these compounds are described. 5. An examination of the mass spectra revealed peaks characteristic of the substituted carbon atoms. Definite assignment of the 17α- and 17β-hydroxyl groups of the epimeric 18-hydroxyoestrogens was possible by characteristic fragmentation of the free steroids. Further, the configuration of 18-hydroxyoestradiol-17β was confirmed by the formation of the dimethylsildioxy derivative of the 3-methylether of the steroid. 6. Both rat and rabbit liver slices reduced 18-hydroxyoestrone to 18-hydroxyoestradiol-17β and some other labile, polar metabolites with properties similar to 2-hydroxylated oestrogens. No formation of 18-hydroxyoestradiol-17α in vitro was observed. 7. The results are discussed with respect to the possible influence of the 18-hydroxyl group on reactions at C-17, as well as the reactions of 18-hydroxylated oestrogens with strong acid (Kober reactions) and alkali.
The fractionation of adenosine-rich oligoribonucleotides on polyethyleneimine-cellulose
Authors: Crossley Jennifer , Mansbridge Jonathan , Williamson Robert
Published: August 2015

After combined pancreatic and T1 ribonuclease treatment of RNA, a characteristic series of products of the type AnN are obtained, where N can be any of the four ribonucleosides. Depending on whether phosphatase treatment is used before the addition of labelled phosphate at the 5′-terminus with bacteriophage phosphokinase, the labelled oligonucleotides obtained may or may not possess a phosphate group at the 3′- as well as the 5′-end. The behaviour of these characteristic products after electrophoresis on cellulose acetate strips followed by chromatography on polyethyleneimine–cellulose thin-layer plates was examined.