bluuebunny/crossref_metadata_2025 huggingface dataset:
Biosynthesis of mustard oil glucosides: 3-benzylmalic acid, a precursor of 2-amino-4-phenylbutyric acid and of gluconasturtiin
Authors: Underhill E. W.
Published: December 2009

2-Amino-4-phenylbutyric acid was isolated from Nasturtium officinale R. Br. (watercress) and identified by gas–liquid and paper chromatography.Various 14C-labelled compounds, including 3-benzylmalic-1,2-14C acid, were fed to N. officinale and their efficiencies as precursors of the aglycone moiety of gluconasturtiin and of 2-amino-4-phenylbutyric acid were determined. The efficiency of conversion of 14C from 3-benzylmalic-1,2-14C acid into gluconasturtiin aglycone was greater than that from DL-phenylalanine-2-14C or -3-14C, acetate-2-14C, shikimic-G-14C acid, and D-glucose-G-14C, but was less than that from DL-2-ammo-4-phenylbutyric-2-14C acid. Degradation of the aglycone obtained from plants fed 3-benzylmalic-1,2-14C acid revealed the tracer had been incorporated specifically into the isothiocyanate carbon and it was concluded that the acid was converted to gluconasturtiin with the loss of C-1. As was reported previously, the carboxyl carbons of acetate and phenylalanine were not incorporated into gluconasturtiin aglycone.The 14C from DL-phenylalanine-2-14C, acetate-1-14C, acetate-2-14C, and from 3-benzylmalic-1,2-14C acid was incorporated into 2-amino-4-phenylbutyric acid with high efficiency. The results support the view that 2-amino-4-phenylbutyric acid is formed from phenylalanine and acetate via 3-benzylmalic acid.
Increase in serum hyaluronidase levels in rats given hydrocortisone or prednisolone
Authors: Bowness J. M. , Harding G.
Published: December 2009

Intraperitoneal injection of 5 mg hydrocortisone to rats was found to cause a considerable increase in serum hyaluronidase activity above the normal level within 12 h, with the maximum response occurring about 18 h after injection. The response at 18 or 24 h increased up to a dose of about 10 mg per rat.Daily injections of 5 mg hydrocortisone or 1.25 mg prednisolone into each of a group of six rats maintained a mean level of serum hyaluronidase which was significantly higher than that of a control group over a period of 6 days. Peaks of activity were found at 1 and 6 days which were almost double the normal mean levels found in both groups on day zero before injections were begun. When the hormone injections were stopped, the hyaluronidase level fell to normal within 24 h.Administration of 20 000 – 50 000 I.U. vitamin A acetate to rats failed to produce an increase in the serum hyaluronidase level even after 13 daily injections. These amounts are known to cause breakdown of cartilage matrix in vivo and disruption of lysosomes in vitro.The absence of any effect of actinomycin D indicated that enzyme induction was not the cause of the increased hyaluronidase activity.
Importance de la forme cristalline de l'acétate de cortisone pour sa déshydrogénation en C-1 par Arthrobacter simplex
Authors: Catroux Gérard , Fournier Jean-Claude , Blachère Henri
Published: December 2009

C-1 dehydrogenation of cortisone acetate by Arthrobacter simplex has been studied in two of its crystalline forms (II and IV). Primarily, transformation of crystalline form in aqueous medium has been studied (phosphate buffer and bacterial culture). In aqueous medium only form IV is stable and dehydrogenated, whatever the conditions of bioconversion. Form II goes to form IV in phosphate buffer but it is stable in bacterial culture. It is dehydrogenated by washed bacteria but not by bacterial culture. Tween 80 does not influence the transformation of crystalline forms. On the other hand, solubilities of the crystalline forms do not change much (phosphate buffer and bacterial culture). These facts suggest the existence of "association" phenomena between colloids in the culture medium and cortisone acetate. This "association" would prevent the dehydrogenation only in the case of form II. This hypothesis is supported by the favorable action of Tween 80 on dehydrogenation of form II in the bacterial culture.
Inhibitory effects of ammonium ions and some amino acids on stimulated brain respiration and cerebral amino acid transport
Authors: Nakazawa S. , Quastel J. H.
Published: December 2009

Ammonium ions cause a suppression of the respiratory response of rat brain cortex slices to electrical stimulation and this is partly reversed by the addition of DL-methionine sulfoxide or L-glutamine but not by addition of L-glutamate or DL-α-methylglutamate. Other basic ions, e.g. tetramethylammonium, pyridine, or pyrimidine, at equivalent concentrations are without effect. Ammonium ions have less inhibitory effect on the respiratory response to high potassium ion concentrations than on that due to application of electrical impulses. They also bring about a marked suppression of the rate of glycine uptake into rat brain cortex slices, the effect being much greater with electrically stimulated brain than with unstimulated brain. Methionine sulfoxide diminishes this suppressive effect. They exercise relatively small inhibitory effects on the depressed rate of glycine uptake obtained in the presence of high potassium ion concentrations. The effect of ammonium ions is considered to be partly due to the fall in cell ATP brought about by the operation of glutamine synthetase. The results are consistent with the view that the extent of stimulation of brain respiration due to electrical impulses or to increased concentration of potassium ions is dependent on the cell level of ATP. L-Glutamate, L-glutamine, or γ-aminobutyrate diminishes the suppressive effects of ammonium ions on glycine influx into brain. L-Glutamate, moreover, diminishes the stimulatory effects of electrical stimulation on brain respiration, lesser effects being produced by L-glutamine or γ-aminobutyrate.
The lactate dehydrogenases of the chicken: estimation and repression during the development of lymphoid and other tissues
Authors: Schultz G. A. , Ruth R. F.
Published: December 2009

Eight organs of 148 embryos, chicks, and chickens were used for estimations of total lactate dehydrogenase (LDH) activity and its distribution among the five principal isoenzymes, LDH-1 to LDH-5. Heart and liver have the greatest total activities, and brain, bursa of Fabricius, and thymus have the least. During development, total activities may follow similar trends. The heart parallels the liver, kidney and spleen parallel gastrocnemius, and brain and bursa parallel thymus. The distribution of activity among the isoenzymes is independent of the parallels in total activity: the heart acquires a great excess of LDH-1 relative to LDH-5, the gastrocnemius acquires an excess of LDH-5 relative to LDH-1, and the six other organs maintain an excess of LDH-1. The separate activities of LDH-4 and LDH-5 may remain very low, as in brain, bursa, and thymus. The total LDH activity of lymphoid and other organs may be reduced by 19-nortestosterone, an androgen which suppresses lymphopoiesis. The effect of this androgen on the LDH activity of the bursa may be detected before gross effects are obvious.
Quantitative determination of pyrimidine nucleotide clusters by a single spectrophotometric measurement
Authors: Spencer John H. , Cape Ronald E. , Marks A. , Mushynski W. E.
Published: December 2009

Determination of pyrimidine oligonucleotide clusters (pyrimidine isostichs) was made in effluents from chromatographic columns by a single spectrophotometric measurement. The method is based on the identical molar absorbance of two components at their isosbestic point, which provides a measure of the total amount of material in each pyrimidine isostich.
Infrared studies of DNA, water, and inositol associations
Authors: Webb S. J. , Bhorjee J. S.
Published: December 2009

Ultraviolet and polarized infrared spectra of oriented films of bacterial DNA have been recorded over a range of relative humidities (R.H.) between 10 and 84%. The films were made from a DNA gel in H2O or D2O with and without 5% (w/v) myo-inositol. In the absence of inositol a large decrease in the dichroic ratio at 1670 cm−1 occurred as the R.H. was lowered between 70 and 30%, indicating the occurrence of considerable disorganization. This was not observed when the DNA was dehydrated in the presence of myo-inositol. A marked increase in absorbance at 2600 Å which occurred on lowering the R.H. from 70 to 50% was prevented also by inositol.These results indicate that myo-inositol can replace water molecules and maintain the DNA in the B configuration during dehydration. The possible significance of these observations in the explanation of certain biological phenomena is discussed.
Synthesis and properties of γ-hydroxyarginine
Authors: Rossa B. A. Santa , Viswanatha T.
Published: December 2009

γ-Hydroxyarginine was prepared by two methods. In method I, the product of reaction between epichlorohydrin and ethyl sodiomalonate was treated with concentrated NH4OH. Then successively, reaction products were treated with O-methylisourea hydrogen sulfate at pH 11.5, bromine, concentrated NH4OH, and trypsin at pH 9.0. In method II, it was prepared by the direct guanidination of γ-hydroxyornithine. The product was homogeneous as indicated by column chromatography and paper electrophoresis. It was converted to arginine upon reduction with HI and red phosphorus, and to γ-hydroxyornithine upon deguanidation by treatment with Ba(OH)2.
Formation and occurrence of N-malonylphenylalanine and related compounds in plants
Authors: Rosa N. , Neish A. C.
Published: December 2009

Shoots of barley seedlings when fed D-phenylalanine convert the amino acid to N-malonylphenylalanine. Some N-acetylphenylalanine is obtained at the same time but this may be an artifact of the isolation procedure since it is readily formed by decarboxylation of the malonylphenylalanine. Feeding experiments with the D- and L-isomers of phenylalanine, valine, leucine, isoleucine, tyrosine, tryptophan, alanine, and glutamic acid showed that barley shoots form the malonyl derivative from all the D-isomers whereas little, if any, is formed from the L-isomers. Similar experiments with phenylalanine and leucine isomers, using seven different plant species, showed that the ability to conjugate the D-isomers (but not the L-isomers) was found in all of the plants tested. It was also observed that the ether-soluble acidic conjugates of a variety of amino acids, possibly malonyl derivatives, occur widely throughout the plant kingdom.
Some energy-producing systems in Bdellovibrio bacteriovorus, strain 6-5-S
Authors: Simpson F. J. , Robinson J.
Published: December 2009

Bdellovibrio bacteriovorus 6-5-S, an obligate bacterial parasite, was grown on cells of Spirillum serpens in 20 l of medium. Maximum numbers of the parasite were attained at 42–55 h, about 2–12 h after there were no viable host cells remaining. Growth of B. bacteriovorus occurred only under aerobic conditions. The organism is rich in catalase. Endogenous respiration of cells and oxidation of NADH by cell extracts is inhibited by cyanide and azide but not by carbon monoxide. Difference spectra indicate the parasite has a cytochrome system and likely couples oxidation to phosphorylation, although efforts to demonstrate fixation of inorganic 32P into organic phosphate failed. Glutamine, glutamate, and asparagine stimulate respiration, and cell extracts contain glutamate and alanine dehydrogenases. B. bacteriovorus 6-5-S also has a tricarboxylic acid cycle, as isocitric dehydrogenase, the α-ketoglutarate dehydrogenase system, succinyl-CoA synthetase, fumarase, and malate dehydrogenase were found in the soluble fraction of the cell extract, and a bound succinic dehydrogenase in the particulate fraction. The glyoxylate cycle may not be present since isocitric lyase could not be detected despite the presence of acetate in the growth medium. Tests on cell extracts for glucose kinase, glucose 6-phosphate dehydrogenase, and 6-phosphogluconate dehydrogenase were also negative. However, aldolase, glyceraldehyde 3-phosphate dehydrogenase, pyruvate kinase, and lactic acid dehydrogenase were present although at rather low levels, indicating that the parasite can obtain energy from the substrate-linked phosphorylations of the glycolytic system.
Size and shape of isolated rat liver mitochondria
Authors: Lusena C. V.
Published: December 2009

The dimensions of unfixed rat liver mitochondria, isolated in 0.44 M sucrose, were measured on photomicrographs taken by phase-contrast microscopy. The lengths ranged from the limit of resolution of the microscope (ca. 0.2 μ) to ca. 5 μ. The smallest measured particle had a calculated volume of 0.008 μ3 and the largest 3.85 μ3. Separate fractions of mitochondria, in order of decreasing sedimentation rate and fragility (Can. J. Biochem. 44, 497), were found to range in mean size from 0.92 μ long × 0.59 μ in diameter (fraction I), through 0.84 μ × 0.59 μ (fraction III) to 0.60 μ × 0.48 μ (fraction V). The limitations and errors in the measurements have been discussed. While these measurements cannot be considered "correct" in an absolute sense, they more closely represent the actual size of unfixed isolated mitochondria than do previously reported measurements, and reliably allow size characterization of different fractions.
Studies on amphibian yolk. VII. Serum phosphoprotein synthesis by vitellogenic females and estrogen-treated males of Xenopus laevis
Authors: Wallace R. A. , Jared D. W.
Published: December 2009

Female toads given 1000 units of human chorionic gonadotropin ovulated within 24 h and began to synthesize a phosphoprotein which appeared, but did not accumulate, in the serum (physiological half-life, 2 days). The period of synthesis lasted about 30 days, after which mature oocytes were once again observed in the ovary. Male toads given a single dose of 0.1–1.0 mg estradiol-17β also immediately began to synthesize a phosphoprotein. The rate of maximum synthesis and the length of time for the maximum to be reached were directly proportional to the amount of estrogen administered. The serum phosphoprotein in male toads, however, had a physiological half-life of approximately 40 days. Ovariectomized females produced a serum phosphoprotein with a physiological half-life similar to that of males. We therefore concluded that under normal conditions the circulating phosphoprotein produced by the liver of the female as a response to estrogen is accumulated by the vitellogenic ovary. The serum phosphoprotein is apparently a lipophosphoprotein complex from which at least one of the yolk proteins, phosvitin, may be derived.
A comparative study of acid deoxyribonucleases extracted from different tissues and species
Authors: Cordonnier Claude , Bernardi Giorgio
Published: December 2009

The chromatographic and enzymic properties, the sedimentation coefficients, and the mechanism of action on native deoxyribonucleic acid (DNA) shown by acid deoxyribonuclease (DNase) preparations obtained from different animal sources were compared. The results obtained strongly indicate that the enzymatic activity is associated with protein molecules endowed with very similar physical, chemical, and enzymic properties. The enzyme levels in the tissues may vary by as much as three orders of magnitude. The highest acid DNase levels are found in lymphatic and tumoral tissues, the lowest ones in cells like sperms and erythrocytes that do not reproduce themselves.
Fatty acids of Aceraceae seed oils
Authors: Hopkins C. Y. , Jevans A. W. , Chisholm M. J.
Published: December 2009

Seed oils of 18 species of Aceraceae (maple family) were examined and their fatty acid compositions were determined. Those of all but one species had substantial amounts of C20, C22, and C24cis-monoenoic acids. Acer rubrum, typical of the group, had 7% eicosenoic, 13% docosenoic, and 4% tetracosenoic acid in the total fatty acids of its oil. The chief isomers, identified in the oil of A. saccharum, were cis-11-eicosenoic, cis-13-docosenoic, and cis-15-tetracosenoic acids. The oils of Dipteronia sinensis and Acer negundo were much like the other Acer oils in composition, but that of A. saccharinum was composed almost entirely of the ordinary C16and C18fatty acids. The results are discussed in relation to the taxonomy of the family.
Drug-metabolizing activity of the human placenta
Authors: Petten G. R. Van , Hirsch G. H. , Cherrington A. D.
Published: December 2009

The drug-metabolizing activity of a 9000 × g supernatant fraction prepared from human placentae obtained immediately after birth was investigated. For comparative purposes a similar rat liver microsomal preparation was used. The metabolism of pentobarbital by oxidation, and of amphetamine by deamination or hydroxylation, proceeded at similar rates in the two tissues. The rate of metabolism of meperidine in the human placental preparation was about two-thirds of that found with the rat liver enzyme. The rate of metabolism of aminopyrine, as determined by measuring the formation of 4-aminoantipyrine or the production of formaldyhyde, was insignificant in the placental preparation, but the metabolism of 4-aminoantipyrine occurred much more rapidly in this tissue than in rat liver. The nitroreductase activity of the human placenta was low; a sixfold activation was achieved by adding a source of glucose 6-phosphate dehydrogenase but the activity was still only one-third of that found in rat liver. The cofactor requirements for the drug-metabolizing enzymes studied were found to be similar in the two tissues. The significance of these findings with respect to the effects of drugs on the mother and the fetus is discussed.
Changes in lipids of cereal seedlings during vernalization
Authors: Redshaw E. S. , Zalik Saul
Published: December 2009

Noticeable changes in lipids were observed during growth of Sangaste fall rye, Prolific spring rye, Kharkov winter wheat, and Red Bobs spring wheat, at vernalizing temperature, over a period of 6 weeks. There was, however, little difference between the trends exhibited by the four varieties, apart from the fact that the rye varieties apparently accumulated more linolenic acid than the wheat varieties whereas the reverse was true for linoleic acid. These results suggested that the lipids under study did not play a direct role in the vernalization response, and the changes observed were a result of low-temperature growth.
Control of progesterone biosynthesis in the bovine corpus luteum: effects of luteinizing hormone and of reduced nicotinamide–adenine dinucleotide phosphate in vitro
Authors: Armstrong David T. , Black Donald L.
Published: December 2009

The effects of luteinizing hormone (LH) and of reduced nicotinamide–adenine dinucleotide phosphate (NADPH) upon in vitro progesterone synthesis by bovine corpus luteum slices incubated for varying periods of time have been examined. The increased net synthesis of progesterone caused by LH was accompanied by markedly increased incorporation of acetate-1-14C into progesterone and decreased incorporation of acetate-1-14C into cholesterol. In most experiments, especially at longer incubation times, exogenous NADPH decreased incorporation of acetate-1-14C into progesterone. The effect of NADPH on incorporation of acetate-1-14C into cholesterol was variable, increasing cholesterol specific activity in some experiments and decreasing it in others. At all time intervals in all experiments, the specific activity of progesterone synthesized was greater than that of the cholesterol remaining in the tissue at the end of the interval. With increasing duration of incubations, specific activity of the progesterone synthesized became increasingly greater than that of cholesterol remaining at the end of the incubation period. These findings suggest that newly synthesized cholesterol is utilized for progesterone formation without coming into equilibrium with a large portion of the intracellular cholesterol pool. Experiments with radioactive cholesterol in vitro indicated that a significant amount of conversion of this precursor occurred in the incubation medium by enzymes which had leaked out of the tissue, and this conversion was strikingly stimulated by exogenous NADPH but not by LH. Rates of progesterone synthesis were greatest in shortest incubations, declining as incubation periods were extended. Highly significant correlations were observed between the increments, caused by LH, in net synthesis (mass) of progesterone, incorporation of acetate-1-14C into progesterone, and lactic acid production. Inhibition by puromycin of the stimulatory action of LH upon progesterone synthesis failed to prevent the stimulatory action of this gonadotropin upon glycolysis. These findings indicate that the stimulation of glycolysis is not a consequence of stimulated progesterone synthesis but may be related to the stimulatory action of LH upon 3′,5′-AMP production.
Gluconeogenesis in rats during cold acclimation
Authors: Penner P. E. , Himms-Hagen Jean
Published: December 2009

The in vivo rate of gluconeogenesis in the male rat was studied during acute exposure and acclimation to a cold environment (5 ± 2°), using an isotopic-tracer method. Four key gluconeogenic-enzyme activities (pyruvate carboxylase (EC 6.4.1.1), phosphoenolpyruvate carboxykinase (EC 4.1.1.32), fructose 1,6-diphosphatase (EC 3.1.3.11), and glucose 6-phosphatase (EC 3.1.3.9)) were compared with the in vivo rates of gluconeogenesis. Phosphoenolpyruvate carboxykinase showed the largest increase in activity in the cold (175%) but this was much smaller than the maximum increase in gluconeogenic rate in cold-stressed rats (485%). Although qualitative similarity between changes in enzyme level and the gluconeogenic rate is evident, a close correlation does not exist. Gluconeogenesis is more active during acute cold exposure (1–7 days) than in chronic cold exposure (3 weeks).These data are interpreted to indicate that the cold-stressed rat which is shivering probably has an accelerated Cori cycle (glucose degradation to lactate in the muscle and resynthesis in the liver) which increases the energy supply (ATP) in the muscle and contributes a minor amount towards thermogenesis in the cold-stressed rat. This contribution diminishes as the capacity for nonshivering thermogenesis in the rat develops.
The thiosulfate-oxidizing enzyme of Ferrobacillus ferrooxidans (Thiobacillus ferrooxidans)
Authors: Silver Marvin , Lundgren D. G.
Published: December 2009

The thiosulfate-oxidizing enzyme tetrathionase was purified about 250-fold from sulfur-grown Ferrobacillus ferrooxidans. It reduced 1 mole of ferricyanide per mole of thiosulfate oxidized, with the production of 0.5 mole of tetrathionate. The pH optimum was 5.0 with acetate buffer, and the Km for thiosulfate was determined to be 9 × 10−4 M. Inhibition studies showed that enzyme activity is not reliant on metal ions or sulfhydryl groups, and no cofactor requirements were found. Tetrathionate was slightly inhibitory to the reaction. A possible role of this enzyme in the oxidation of sulfur and thiosulfate is discussed.
Effect of adrenalectomy and hypophysectomy on responses of rat liver enzymes to high-protein diets
Authors: Freedland R. A.
Published: December 2009

Although many enzymes are increased by either a high-protein diet or cortisol adminstration, there was no evidence of a glucocorticoid requirement for the high-protein mediated increases. This was particularly noticeable for enzymes markedly increased by feeding a high-protein diet. Neither adrenalectomy nor hypophysectomy prevented the diet-mediated increases, although in certain instances the responses were decreased. Many enzymes which were unaffected or decreased in the intact rat by feeding a high-protein diet had markedly different responses after endocrine removal. There did not appear to be a general or simple pattern of these altered responses. Therefore predictions on possible activity changes could not be made, except for those enzymes normally increased by a high-protein diet on the basis of metabolic function or hormonal effects. Possible hormonal controls of these changes in enzyme activity are discussed.
Phospholipids. XVII. Synthesis of ethylene glycolphosphonic acid analogues of lecithins
Authors: Baer Erich , Robinson Ranga
Published: December 2009

The synthesis of ethylene glycolphosphonic acid analogues of lecithins, a new type of pbosphonolipids, is reported. The preparation of myristoyl, palmitoyl, and stearoyl ethylene glycol-(2-trimethylammoniumethyl)phosphonate is described in detail. They were obtained by phosphonylating the corresponding esters of ethylene glycol with (2-bromoethyl)phosphonic acid monochloride and triethylamine, and treating the resulting acyl glycol-(2-bromoethyl)phosphonates in dimethylformamide with trimethylamine at 50–55° for 3 days. The glycolphosphonolecithins (phosphonic acid analogues of glycollecithin) are highly soluble in water and possess strong hemolytic activity. On hydrolysis by lecithinase C (Clostridium welchii) or alkali (Dawson procedure) they yield the corresponding monoacyl glycols and ethylene glycol-(2-trimethylammoniumethyl)phosphonate, respectively. The identification of ethylene glycolphosphonolecithins in the presence of phosphonolecithins, glycollecithins, and lecithins by descending paper chromatography of their saponification products, obtained by mild alkaline hydrolysis, is described.
Use of 13C in biosynthetic studies. Incorporation of isotopically labeled acetate and aspartate into fusaric acid
Authors: Desaty D. , McInnes A. G. , Smith D. G. , Vining L. C.
Published: December 2009

Acetate-1-13C, acetate-2-13C, and aspartate-4-13C were used as substrates to elucidate the biosynthetic pathway for fusaric acid, the phytotoxic metabolite of Fusarium oxysporum Schlecht. It was established that C-2, C-3, C-4, and C-7 were derived from acetate via aspartate or a related four-carbon dicarboxylic acid, whereas C-5, C-6, C-8, C-9, C-10, and C-11 were derived more directly from acetate. The 13C-labeling patterns were determined by measuring the relative intensities of the 13C—H satellites by proton magnetic resonance spectroscopy.Further information was derived from experiments with D- and L-isomers of aspartate-1-14C and L-aspartate-1-14C:15N. Radioactivity from both enantiomers of aspartate-1-14C was incorporated into fusaric acid, but more efficiently from the L-isomer. Furthermore, 15N was incorporated more efficiently into fusaric acid and the aspartic acid of mycelial protein than was 14C. These results suggest that aspartic acid is metabolized to fusaric acid via oxalacetate, and that L-aspartate serves as a donor of nitrogen, in an amino-transferase reaction, to a separate oxalacetate pool of primarily endogenous origin.
Incorporation of ethanolamine-1,2-14C into plant microsomal phospholipids
Authors: Vandor S. L. , Richardson K. E.
Published: December 2009

The incorporation of ethanolamine-1,2-14C into phospholipid and the decarboxylation of phosphatidyl-serine-1,2-14C by etiolated pea seedling "microsomal suspensions" have been investigated. Optimum incorporation occurred with phosphate buffer, pH 8.5, in the presence of 2.9 × 10−3 M CaCl2. Toluene, phospholipase D, and reduced glutathione stimulated ethanolamine-1,2-14C incorporation. Higher concentrations of CaCl2, imidazole buffer, and Tris buffer were inhibitory. Other divalent cations, ATP, CTP, and CMP were without effect. L-Serine and choline were also incorporated into phospholipids by pea "microsomal suspensions" and competitively inhibited the incorporation of ethanolamine-1,2-14C. Inhibition was also observed with D-serine and glycerol, but not with methanol, ethanol, propane-1-ol, and propane-2-ol. The formation of 14CO2 by the decarboxylation of serine-U-14C by "microsomal suspensions" was also stimulated by Ca2+ and inhibited by ethanolamine. The experimental results suggest that the incorporation of ethanolamine and the decarboxylation of serine in plants proceeds by essentially the same Ca2+-requiring mechanisms reported for animals.
Glycosidases in bovine milk: α-mannosidase and its inhibition by zwitterions
Authors: Mellors A. , Harwalkar V. R.
Published: December 2009

α-Mannosidase is present in bovine milk and is associated with the β-casein fraction following polyacrylamide gel electrophoresis. It was separated from the casein complex by ammonium sulfate precipitation in the presence of 10% (v/v) ethanol. Zinc or manganese ions are required for maximum activity and the enzyme is very labile. The optimum pH for the hydrolysis of p-nitrophenyl α-mannoside is about 3. In the presence of amino acid buffers the enzyme is inhibited. For dibasic amino acids this inhibition is inversely related to the [Formula: see text] of the amino acid and is apparently due to inhibition by zwitterions. High concentrations of the substrate p-nitrophenyl α-mannoside are inhibitory, and the apparent Km for this hydrolysis is 1.2 mM.
The formation of sulfenyl iodides as intermediates during the in vitro iodination of tyrosine by calf thyroid homogenates
Authors: Fawcett David M.
Published: December 2009

Following dialysis against chlorinated water, the soluble protein fraction of calf thyroid homogenates readily iodinated tyrosine when supplemented with iodide at 37 °C. Addition of iodide to an active preparation also resulted in a rapid increase in optical density at 355 mμ, characteristic of sulfenyl iodide formation. The thyroidal sulfenyl iodide was stable for long periods at 5 °C, but at 20 °C or 37 °C it disappeared with the formation of monoiodotyrosine (MIT) and diiodotyrosine (DIT). The decomposition of the reactive thyroidal species in the presence of 2-mercaptoethanol was characteristic of the behaviour of sulfenyl iodides but not I3−. Excess iodide increased the stability of the sulfenyl iodide but inhibited the iodination of tyrosine. Thiourea inhibited both sulfenyl iodide formation and iodination.Evidence is presented that the chlorine activation of thyroid protein involved sulfenyl chloride formation. During dialysis of thyroid protein against 36Cl-chlorinated water a significant proportion of the 36Cl became bound to protein. Protein-bound and nonprotein-bound 36Cl were separated by filtration through Sephadex G-50. Incubation of the protein-bound fraction with 131I-iodide resulted in displacement of 36Cl by 131I and the formation of 131I-MIT and 131I-DIT. These studies support the hypothesis that thyroidal iodotyrosine formation may involve sulfenyl iodide intermediates.
Ribosomal proteins from goose reticulocytes are not histones
Authors: Neelin J. M. , Vidali G.
Published: December 2009

Ribosomes were isolated from goose reticulocytes after lysis with saponin in 50 mM KCl, 1.5 mM MgCl2, 1 mM Tris, pH 7.5. Maximum yields of ribosomes were obtained about 4 days after injection of the birds with Phenylhydrazine, but ribosomal proteins did not vary with the stage of recovery.Ribosomal proteins (extracted with either HCl–urea or LiCl–urea) differed generally from histones (extracted with either HCl or HCl–urea) according to amino acid composition and to electrophoretic patterns in starch gel and in Polyacrylamide gel, but a few zones of ribosomal protein appeared to coincide electrophoretically with the main histone components. Since all of the former proteins were eluted unretarded from Amberlite CG-50 in 9% guanidinium chloride, in which all histones are adsorbed, we conclude that histones and ribosomal proteins are different classes of protein.The hazards of assuming chemical identities of proteins on the basis of limited electrophoretic evidence and the risks of misleading cross-contamination of cell fractions were demonstrated.
The performic acid oxidation of egg-white lysozyme
Authors: Finlayson A. J.
Published: December 2009

The performic acid oxidation of egg-white lysozyme has been studied using amounts of oxidant varying from 0.5 mole to 3 moles excess. The results show that excess performic acid causes substantial peptide bond hydrolysis both at the tryptophan residues and at other places in the molecule. The yields of kynurenin vary with the amount of oxidant and are greater than those found for the performic acid oxidation of tryptophan itself. The results also show that the tryptophyl residues are more susceptible to oxidation than are the cystine residues and that oxidations with less than stoichiometric amounts of oxidant produce an intermediate from tryptophyl residues which does not give kynurenin upon acid hydrolysis.
Studies on the plasma glycolipoprotein synthesis by the isolated perfused liver: effect of early choline deficiency
Authors: Mookerjea Sailen
Published: December 2009

Isolated liver perfusion preparations have been used to study the incorporation of glucosamine-1-14C into plasma glycoproteins and glycolipoproteins. The livers obtained from 2-day-choline-deficient rats and perfused with blood obtained from rats on similar dietary treatment showed, compared to controls, an impairment of incorporation of radioactive glucosamine into the trichloroacetic-acid-insoluble protein fraction of plasma during the progress of perfusion. The rate of disappearance of radioactivity in the trichloroacetic-acid-soluble fraction of plasma during perfusion was not affected by choline deficiency. Synthesis of plasma glycolipoproteins as judged by the progressively increased incorporation of radioactivity showed a very significant impairment of synthesis of very low-density (d < 1.006) and low-density (d > 1.006–1.063) glycolipoproteins in early choline deficiency. A similar inhibition of synthesis of plasma proteins of d > 1.21 ("lipid acceptor protein") was observed, whereas the synthesis of high-density lipoproteins (d < 1.063–1.21) was not affected in choline deficiency.The fatty liver in choline deficiency appears to result from an impairment of plasma low-density glycolipoprotein synthesis. A postulation has been made on the stepwise biosynthesis of plasma lipoproteins on the basis of these and earlier studies.
Characterization of placental isoenzyme of alkaline phosphatase in human pregnancy serum
Authors: Ghosh N. K. , Fishman W. H.
Published: December 2009

Human placental alkaline phosphatase isoenzyme has been characterized in pregnancy serum by several biochemical criteria. The total serum alkaline phosphatase, its L-phenylalanine-sensitive moiety, heat inactivation, and the ratio of enzyme activity at pH 10.7 versus 9.8 (10.7/9.8 R) were measured during parturition and 59 weeks of pre- and post-natal periods. The extent of L-phenylalanine inhibition, heat stability, and 10.7/9.8 R of serum alkaline phosphatase progressively increased during gestation attaining maximum values during the delivery, after which they gradually declined. The electrophoretic behaviors of alkaline phosphatase isoenzymes of pregnancy sera were followed by starch- and Sephadex-gel electrophoreses. Alkaline phosphatase has been purified 300-fold from the placenta of the subject whose serum enzyme was investigated. The biochemical properties, including the electrophoretic behavior and neuraminidase sensitivity of heat-stable alkaline phosphastase in pregnancy sera at term, were comparable to those of purified placental alkaline phosphatase. The values for 10.7/9.8 R of the pregnancy sera were statistically different from those of sera from normal nonpregnant women. The results obtained in this study suggest that the enhanced level of pregnancy serum alkaline phosphatase is due to the enrichment of the circulation with an isoenzyme of placental origin.
Study of sugars with cysteine – sulfuric acid reagents
Authors: Thibert R. J. , Mazzuchin A.
Published: December 2009

A modified procedure for the use of the cysteine – sulfuric acid reagent for the determination of monosaccharide has been devised. The procedure utilizes a 9-ml volume of H2O:H2SO4 at a ratio of 1:7 which results in a rapid nonspecific method for the determination of pentoses, hexoses, and hexuronic acids in simple solutions. α-Substituted cysteines are compared to cysteine hydrochloride as color reagents. The accuracy of the modified procedure is about ± 2% in the optimum concentration range. The time required for a complete analysis is about 1 h for pentoses and hexuronic acids and 30 min for hexoses.
Involvement of free radicals in the oxidative degradation of indole-3-acetic acid
Authors: Parups E. V.
Published: December 2009

The enzymic or nonenzymic oxidation of indole-3-acetic acid (IAA) was promoted in the presence of the stable free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH). The involvement of DPPH with the IAA free-radicals in the nonenzymic and the peroxidase-catalyzed oxidations was discussed. Methylene-oxindole was identified as a breakdown product of IAA, indicating a pathway operative with this radical.
Nucleic acids and ribonucleases of wheat leaves and chloroplasts
Authors: Hadziyev D. , Mehta S. L. , Zalik Saul
Published: December 2009

High ribonuclease B activity associated with chloroplasts is localized in the stroma and the chloroplast membrane, and a negligible amount is associated with mitochondria and ribosomes. The amount of this enzyme retained by the chloroplast is affected by the isolation medium used. Cold treatment enhanced its activity. Ribonuclease A, which is confined to the cytoplasm, is removed only to the extent of 50% by bentonite. Part of ribonuclease A is bound in an inactive complex. Ribonuclease B increases more than A during shoot development. The methylated albumin kieselguhr elution profiles of nucleic acids are affected by ribonucleases. Mainly the ribosomal types of RNA are degraded and this is most pronounced for chloroplasts from older leaves. The two peaks for DNA have been tentatively attributed mainly to chloroplast and nuclear DNA. A considerable amount of nucleic acid, assumed to be mostly mRNA, was bound tenaciously to the column. This fraction decreased with age of leaves. Pulse labeling resulted in two DNA–RNA hybrids which were readily susceptible to endogenous enzyme.
The relationship between Mg2+-stimulated ATPase activity and glycogen content in rat liver
Authors: Rubenstein B. , Scholefield P. G.
Published: December 2009

During starvation there is an increase in the ATPase activity of a postmitochondrial fraction of rat liver. The increase is relatively specific for ATP and there is no change in the Na+,K+-stimulated ATPase activity. A corresponding increase in ATPase activity is found on pretreatment of the rat with glucagon and in tumor-bearing animals. The increase has been correlated with increase in phosphorylase activity and decrease in glycogen content under in vivo and in vitro conditions. Treatment of fasted animals with glucose or sucrose restores the glycogen content and diminishes the ATPase activity to normal levels, but puromycin is without effect. It is proposed that a physical association of glycogen with Mg2+-stimulated ATPase activity prevents the enzyme activity from being expressed.
Inhibition of urea cycle enzymes by aspartic acid analogues
Authors: Bayer S. M. , McMurray W. C.
Published: December 2009

The inhibition of urea biosynthesis by analogues of aspartic acid was studied in vitro in homogenates and enzyme preparations from rat liver. Each of the analogues tested inhibited the overall utilization of citrulline for urea formation by liver homogenates. The concentrations required to give 50% inhibition were: N-allylaspartate, 0.248 M; α-methylaspartate, 0.140 M; β-methylaspartate, 0.078 M; and β-hydroxy-β-methylaspartate, 0.038 M. The β-substituted analogues partly replaced aspartate as a substrate for citrulline utilization in liver homogenates. The replacement was probably due to transamination of the analogues with oxaloacetate, since the effect was not observed when the assay mixture did not contain a substrate which could yield oxaloacetate.A study of individual enzymes of the urea cycle showed that arginase, argininosuccinase, and ornithine transcarbamylase were not greatly affected by the analogues. However, carbamyl phosphate synthetase as well as argininosuccinate synthetase were strongly inhibited, suggesting that the analogues act by some mechanism other than simple antagonism of aspartate. Part of the inhibition was related to the ability of the analogues to complex Mg2+, since increased concentrations of Mg2+ prevented the inhibition of carbamyl phosphate synthetase and reduced the inhibition of argininosuccinate synthetase by α-methylaspartate and N-allylaspartate. In addition, β-methylaspartate was found to depress oxidative and phosphorylative reactions, thus interfering with the energy production required for urea formation.Aspartic acid in concentrations comparable with those required to effect inhibition by α-methylaspartate produced a marked inhibition of citrulline utilization in liver homogenates and of purified argininosuccinate synthetase. This observation suggests that part of the inhibitions observed with the analogues are of the "substrate type".
Physicochemical studies on the aggregation of bovine cardiac tropomyosin with ionic strength
Authors: McCubbin William D. , Kay Cyril M.
Published: December 2009

The aggregation of bovine cardiac tropomyosin as a function of ionic strength has been studied by the techniques of sedimentation velocity, sedimentation equilibrium, osmometry, viscometry, and optical rotatory dispersion. The measurements indicate that in aqueous buffers at neutral pH and at ionic strengths below 0.6, cardiac tropomyosin is heterogeneous and consists of a monomer in equilibrium with its aggregates. Dissociation of the aggregates occurs on dilution to yield a molecular weight species of approximately 70 000, in very good agreement with the value obtained at high ionic strength. These observations essentially parallel similar findings noted for the polymerization of skeletal tropomyosin, with the exception that the cardiac protein shows no tendency to polymerize at high ionic strength. The virtual constancy of all the optical rotatory dispersion parameters with polymerization suggests that the association is probably linear rather than lateral, with no accompanying changes in secondary and tertiary structures of the individual monomers.
Further studies of L-arginine biosynthesis in germinating pea seeds. Evidence for the presence of argininosuccinate synthetase in cotyledon extracts
Authors: Shargool P. D. , Cossins E. A.
Published: December 2009

The synthesis and metabolism of arginine in germinating peas was examined by supplying micromolar quantities of L-citruiline-carbamyl-14C, DL-arginine-carbamyl-14C, and DL-arginine-5-14C to imbibing seeds. Citrulline was readily incorporated into arginine, but the labelled arginine solutions were not extensively metabolized.Extracts of 1-day-old cotyledons were found to catalyze the synthesis of arginine from citrulline in a reaction having absolute requirements for ATP, L-aspartate, and magnesium ions. The extracts were fractionated by (NH4)2SO4 precipitation followed by gel filtration on columns of Sephadex G-50 and G-200. These treatments increased the specific enzyme activity by approximately 36 times. After such treatments the preparations still contained appreciable amounts of argininosuccinate lyase (L-argininosuccinate arginine-lyase, EC 4.3.2.1) activity. The rate of arginine synthesis was altered by increasing the concentrations of L-citrulline, L-aspartate, and ATP. The latter compounds were found to be inhibitory at concentrations of 1 μmole/ml and 4 μmoles/ml, respectively. Arginine synthesis was markedly affected by pH and by additions of arginine and argininosuccinate. It is concluded that germinating pea cotyledons contain appreciable levels of argirrinosuccmate synthetase (L-citrulline:L-aspartate ligase (AMP), EC 6.3.4.5), and furthermore, that this enzyme has importance in arginine biosynthesis during germination.
The combined effects of temperature and dilution on the activity and feedback inhibition of yeast aspartate transcarbamylase
Authors: Kaplan J. G. , Messmer Irmgard
Published: December 2009

Dilution of a partially purified preparation of yeast aspartate transcarbamylase caused only a small loss of feedback inhibition and no change in specific activity when the assay was carried out at low temperature (0–10 °C). As the temperature of assay was increased, there was in the case of the dilute preparation a progressive loss of feedback inhibition coupled with a sharp increase in specific activity, reaching a level 400–500% that of the concentrated preparations. The data suggest that this is due to a dissociation into subunits possessing high aspartate transcarbamylase activity but lacking the regulatory site.
Inactivation of hemolytic actiyities of serum complement by phenothiazines
Authors: Mao Thomas S. S. , Noval Joseph J. , Pellerin Paul , Plescia Otto J.
Published: December 2009

The hemolytic titers of human and guinea pig sera were greatly reduced by pretreatment with any of several phenothiazines. The anti-complement activity of the phenothiazines depended on the nature of substituents at positions 2 and 10. In the promazine group, the relative effectiveness of the position-2 substituents was in the order H > Cl > OCH3 > CF3. The presence of a piperazinyl group in the chain at position 10 conferred strong anti-complement activity. Thioridazine was the most potent inhibitor among the 12 phenothiazines studied. Complement components C′2 and C′4 in both human and guinea pig sera were more sensitive than other components to inactivation by phenothiazines. Phenothiazines administered orally in moderate doses did not lower the complement level of serum in three subjects. There was no correlation between anti-complement activity of the phenothiazines and their relative therapeutic potency.
Phosphonic acid analogues of carbohydrate metabolites. I. Synthesis of L- and D-dihydroxypropylphosphonic acid
Authors: Baer Erich , Basu Hemendra
Published: December 2009

A synthesis of the phosphonic acid analogues of L-α- and D-α-glycerophosphoric acid, viz. L- and D-dihydroxypropylphosphonic acid, is described. The L-dihydroxypropylphosphonic acid was obtained by treating acetone α-iodo-L-propylene glycol with triethyl phosphite at 120–125° for 24 h, hydrolyzing the condensation product acetone L-dihydroxypropylphosphonic acid diethyl ester with 2 N sulfuric acid at 100° for 48 h, and isolating the L-dihydroxypropylphosphonic acid as barium salt. The D-dihydroxypropylphosphonic acid was prepared in the same manner from acetone α-iodo-D-propylene glycol. The barium salts are readily soluble in cold water, much less soluble in hot water, and insoluble in the more common organic solvents. Dihydroxypropylphosphonic acid and α-glycerophosphoric acid can be distinguished from each other by their different behaviors towards hot mineral acids, and by the infrared spectra, n.m.r. spectra, and optical rotations of their barium salts.
Effects of X-radiation on thymidine incorporation and deoxyribonucleoprotein integrity in rat tissues
Authors: Myers D. K. , Ram S.
Published: December 2009

The early effect of X-radiation on thymidine incorporation into deoxyribonucleic acid (DNA) did not differ markedly in rat tissues which are resistant and those which are sensitive to the lethal effects of irradiation. Inhibition of DNA synthesis was accompanied by loss of integrity of deoxyribonucleoprotein (DNAP) in all tissues examined during the postradiation period. The cells of radioresistant tissues were able to repair the postradiation damage to DNAP, while the degradation of DNAP continued unchecked in radiosensitive tissues during a 24-h observation period.
Purification and properties of a β-hexosidase from Sporobolomyces singularis
Authors: Blakely J. A. , MacKenzie S. L.
Published: December 2009

A β-hexosidase has been isolated from Sporobolomyces singularis by conventional techniques involving ammonium sulfate precipitation and chromatography on columns of Sephadex G-200 and DEAE-Sephadex A-50. Electrophoresis on polyacrylamide gel was used as the final preparative step. The sedimentation coefficient (s°20,w) of the enzyme was 7.6 and its molecular weight was in the range 140 000–145 000. Although the β-hexosidase performed the functions of a β-D-galactoside galactohydrolase (β-galactosidase), it also catalyzed the hydrolytic function normally performed by a β-D-glucoside glucohydrolase; both these functions appear to reside in the same molecule.