bluuebunny/crossref_metadata_2025 huggingface dataset:
EVIDENCE FOR THE INDUCTION OF URIDINE AND DEOXY-URIDINE PHOSPHORYLASES OF REGENERATING RAT LIVER IN VITRO
Authors: Yamada Esther W.
Published: December 2009

Increases in the specific activities of undine and deoxyuridine phosphorylases of slices of regenerating rat liver were found 4 hours after incubation in tissue-culture medium containing uridine or 6-azauridine. These increases were not found when the tissue-culture medium contained either 8-azaguanine or puromycin, or when it lacked amino acids. Although both uridine and 6-azauridine were more effective in increasing the specific activity of uridine phosphorylase than that of deoxyuridine phosphorylase, azauridine was more effective than uridine in increasing the specific activities of both enzymes.In time studies, in which slices of regenerating rat liver were incubated in tissue-culture medium containing optimal concentrations of uridine, the specific activities of the two enzymes reached maximum levels at 3–4 hours. Puromycin prevented these increases.
ISOLATION, PURIFICATION, AND PROPERTIES OF CELLULASES FROM ASPERGILLUS TERREUS AND PENICILLIUM VARIABILE
Authors: Pal P. N. , Ghosh B. L.
Published: December 2009

Cellulases from A. terreus and P. variabile were isolated and purified nearly 100-fold. Enzyme production reached a maximum on the seventh day of incubation. The properties and activities of the purified cellulases were studied. At constant enzyme concentration, the activity increased with the increase in substrate concentration but the percentage of the substrate hydrolyzed decreased. Of the two purified cellulases, that from A. terreus seemed to be a purer product and was tested for its homogeneity and enzymic nature. A unienzymic nature was indicated by the observation that no resolution of the enzyme could be effected by electrophoresis. Standard solubility and diffusion tests gave no indication of heterogeneity in the purified cellulase; this finding was confirmed by the presence of only one peak in both gel filtration and ion-exchange chromatography. Random splitting of α-cellulose and carboxymethylcellulose (CMC) was indicated.
ENZYME INHIBITION BY DERIVATIVES OF PHENOTHIAZINE: VII. INHIBITION OF GLUCOSE-6-PHOSPHATE DEHYDROGENASE ACTIVITY OF RABBIT ERYTHROCYTES
Authors: Collier H. B. , Gray M. W.
Published: December 2009

The effects of various phenothiazine derivatives were tested, by a NADP+-coupled spectrophotometric assay, on the glucose-6-phosphate dehydrogenase activity of hemolysates of rabbit erythrocytes. Phenothiazine, phenothiazine sulfoxide, thionol, promazine, chlorpromazine, and methylene blue were relatively weak inhibitors. Powerful inhibitors (concentration, for 50% inhibition, I50, in parentheses) were phenothiazone (90 μM) and New Methylene Blue N (75 μM). These two compounds caused a slow direct oxidation of NADPH; however, they appeared to exert an action on the enzyme as well. The enzyme was not inhibited by 2,6-dichlorophenol–indophenol, which is employed in a dye-reduction assay.The enzyme system was readily inactivated by ethanol (I5o = 1.4 M). Prior addition of NADP+afforded some protection.
METABOLISM OF BENZIMIDAZOLE IN WHEAT: I. FORMATION OF BENZIMIDAZOLE NUCLEOTIDE
Authors: Kapoor M. , Waygood E. R.
Published: December 2009

An enzyme, probably benzimidazole nucleotide:pyrophosphate phosphoribosyl transferase, has been demonstrated in the 33–65% (NH4)2SO4fraction of wheat embryos. The enzyme was assayed indirectly by the apparent inhibition of the analogous orotidine-5′-phosphate pyrophosphorylase caused by benzimidazole competing with orotate for P-ribosyl-PP. Both enzymes were in the same fraction. The reaction product, benzimidazole nucleotide, was separated by paper electrophoresis and thin-layer and column chromatography, and was identified by chemical and spectral analysis. Kinetin showed similar competitive behavior.
METABOLISM OF BENZIMIDAZOLE IN WHEAT: II. FORMATION OF BENZIMIDAZOLE ADENINE DINUCLEOTIDE AND ITS PRODUCTS
Authors: Kapoor M. , Waygood E. R.
Published: December 2009

A glycohydrolase (NAD nucleosidase) in the particulate fraction of wheat embryos catalyzes the splitting of the pyridinium N-ribosyl bond of NAD. The particles also catalyze the substitution of benzimidazole for the nicotinamide moiety of NAD. The products of the reaction, benzimidazole nucleoside and adenine nucleotide, probably arise by 5′-nucleotidase activity on benzimidazole adenine dinucleotide. An alternative mechanism has been proposed and the reaction is discussed in relation to the NAD-accelerated senescence of leaves of wheat and Elodea.
BIOSYNTHESIS OF MUSTARD OIL GLUCOSIDES: V. FORMATION OF GLUCONASTURTIIN FROML-γ-PHENYLBUTYRINE-C14-N15IN WATERCRESS
Authors: Underbill E. W.
Published: December 2009

C14-Labelled compounds were fed to watercress (Nasturtium officinale R. Br.) and their efficiency as precursors of the aglycone portion of gluconasturtiin compared. Phenylalanine-2- and -3-C14and sodium acetate-2-C14were efficient precursors of the aglycone but neither compound was as efficient a precursor as γ-phenylbutyrine (2-amino-4-phenylbutyric acid). Approximately 40% of the C14from γ-phenylbutyrine-2- or -3-C14was incorporated into the aglycone side chain. Results of studies with doubly labelled L-γ-phenylbutyrine-C14-N15show that the amino nitrogen is incorporated directly into the thioglucoside. Evidence that indicates that D-γ-phenylbutyrine is converted to its L-isomer by the plant is also presented. The results of an isotope competition experiment provide some evidence for the existence of a chain-lengthening pathway (analogous to the formation of leucine from valine) for the biosynthesis of γ-phenylbutyrine from phenylalanine and acetate in watercress.
BIOSYNTHESIS OF MUSTARD OIL GLUCOSIDES: VI. BIOSYNTHESIS OF GLUCOBARBARIN IN RESEDA LUTEOLA L.
Authors: Underhill E. W.
Published: December 2009

A number of C14-labelled compounds were fed to Reseda luteola L.; after a 24-hour period of metabolism, the thioglucoside aglycone (5-phenyl-2-oxazolidinethione) was isolated and its specific activity determined. In some instances the aglycone was degraded to determine the distribution of C14.DL-γ-Phenylbutyrine (2-amino-4-phenylbutyric acid) was the most efficient precursor of the aglycone, followed by phenylalanine and acetate; the carboxyl carbon of these compounds was not incorporated into the thioglucoside aglycone. Little or no randomization of C14 in the aglycone resulted from feeding DL-γ-phenylbutyrine-2- and -3-C14, DL-phenylalanine-2- and -3-C14, and acetate-2-C14. The conversion of C14 from 10 additional compounds into the aglycone was less than that from D-glucose-G-C14. Isotope competition experiments suggest that β-benzylmalic acid also may be a precursor. It appears that the C6–C3 aglycone is formed from phenylalanine and acetate via C6–C5 and C6–C4 intermediates (including γ-phenylbutyrine or its keto acid analogue) in a manner analogous to the formation of gluconasturtiin in watercress. The carbon-14 and nitrogen-15 of L-phenylalanine-G-C14-N15 and of DL-γ-phenylbutyrine-2-C14-N15 were not incorporated as a unit into the aglycone of glucobarbarin.
BIOSYNTHESIS OF NUCLEOTIDES IN WHEAT: I. PURINES FROM C14-LABELLED COMPOUNDS
Authors: Robern H. , Wang D. , Waygood E. R.
Published: December 2009

Glycine-2-C14and 5-amino-4-imidazole carboxamide-2-C14(AICA) were fed to wheat leaves and embryos respectively. The soluble fractions were treated with Norit A, and the Norit eluates were subjected to paper chromatographic analysis to identify the purines and derivatives synthesized from the labelled compounds. Glycine and AICA were shown to be precursors of purine nucleotides, and both compounds gained access to nucleic acids (AICA being more efficient). The results are discussed in relation to recent investigations on purine nucleotide synthesis in the wheat plant.
THE GREY (ATLANTIC) SEAL; FATTY ACID COMPOSITION OF THE BLUBBER FROM A LACTATING FEMALE
Authors: Ackman R. G. , Jangaard P. M.
Published: December 2009

The fatty acid composition of the blubber from a lactating female seal has been examined in detail. Comparisons with the fatty acid composition of a milk sample and with generally observed blubber fatty acid compositions in other species suggest selective utilization of particular depot fat fatty acids during the nursing period.
THE EFFECT OF NEUTRAL SALTS ON PARTICLE PREPARATIONS FROM RAT LIVER: I. THE EFFECT OF NEUTRAL SALT ON PYRUVATE OXIDATION
Authors: Tustanoff E. R. , Stewart H. B.
Published: December 2009

The effect of neutral salts on the utilization of pyruvate by saline-washed particles from rat liver has been investigated in the presence of ATP, Mg++, and fluoride. Addition of increasing quantities of NaCl, KCl, LiCl, or an osmolar equivalent of sucrose to particle preparations metabolizing pyruvate produced a pronounced inhibition of oxygen consumption, which was characterized by a sharp threshold of onset. In the presence of relatively high concentrations of salt, lactate formation is reduced but ketone body synthesis is only slightly impaired. No protection from salt inhibition was afforded by pretreatment of the particles with pyruvate. Fluoride appears to sustain the inhibition produced by the osmotic activity of NaCl. The inhibition is associated with a lack of utilization of pyruvate but produces no change in oxaloacetate levels. The oxidation of D-(−)-β-hydroxybutyrate under these conditions seems to be unimpaired. Within limits, the elevation of the osmolarity appeared to be without effect on oxidative phosphorylation, regardless of the substrate, but was associated with certain well-defined morphological changes in the mitochondrion.
CARRAGEENAN AS A DIETARY CONSTITUENT FOR THE RAT: FAECAL EXCRETION, NITROGEN ABSORPTION, AND GROWTH
Authors: Hawkins W. W. , Yaphe W.
Published: December 2009

At levels of 2–20% in the diet of young rats, carrageenan is quantitatively excreted in the faeces.In diets fed in equal amounts, both cellulose and carrageenan, when substituted for starch in various proportions, affect the growth of young rats. Beginning at levels of 10–15%, however, growth is slower with carrageenan, and there is less absorption of dietary nitrogen,Carrageenan, like cellulose, has no nutritional value. The depression of nitrogen absorption could explain the slower growth rate that occurs with carrageenan in the diet.
OCCURRENCE AND PROPERTIES OF L-AMINOACID:2-GLYOXYLATE AMINOTRANSFERASE IN PLANTS
Authors: Cossins E. A. , Sinha S. K.
Published: December 2009

Extracts prepared from a variety of higher plant tissues have been examined for L-aminoacid:2-glyoxylate aminotransferase (glyoxylate transaminase) activity. This enzyme has been detected in extracts prepared from sunflower cotyledons, corn coleoptiles, mature pea leaves, and carrot storage tissues.Measurement of glyoxylate transaminase activity was based on ability of the extracts to convert glyoxylate- 1,2-C14 to glycine-1,2-C14 in the presence of a suitable amino group donor.Properties of this enzyme system, including amino donor requirements, inhibition, pH optima, and reversibility, have been studied using extracts prepared from mature pea leaves. In sunflower cotyledons, glyoxylate transaminase activity decreased during germination. Studies of the intracellular localization of this enzyme have shown that glyoxylate transamination occurs mainly in the cytoplasm.
ESTERIFICATION OF INTRA- AND EXTRA-CELLULAR FREE FATTY ACIDS BY RAT ADIPOSE TISSUE
Authors: Rubinstein David , Daniel Anna M. , Lechter Lydia , Beck John C.
Published: December 2009

The esterification of intracellular and extracellular FFA by rat adipose tissue in vitro was investigated. The rate of incorporation of FFA into neutral lipids was proportional to the FFA concentration in the incubation medium. Both in the presence and absence of a lipolytic agent (epinephrine), heptadecanoate-1-C14, which is not specifically diluted by tissue fatty acids, was esterified in the same manner as palmitate-9,10-H3. Stearate, palmitate, and oleate were esterified at similar rates by adipose tissue taken from fed animals and incubated with glucose. The rate of esterification of one fatty acid was not significantly affected by the presence of another. Similar results were obtained when tissues were taken from fasted animals and incubated in the absence of glucose, except that the overall rate of esterification was diminished and FFA accumulated in the tissue. It is concluded that long-chain fatty acids do not compete for esterification or entry into the adipose tissue cell.In some experiments tissue FFA esterification was studied by measuring the incorporation of glucose-U-C14carbons into glyceride–glycerol. Esterification, assayed in this manner, increased when albumin was present in the incubation medium and allowed FFA to diffuse from the tissue. However, pre-incubation of adipose tissue in medium containing labelled FFA indicates that much of the intracellular FFA may be esterified without its mixing with the extracellular FFA pool.
CHANGES IN THE RELATIVE AMOUNTS OF ASCORBIC ACID AND GLYCOGEN IN DENERVATED RAT GASTROCNEMIUS MUSCLE
Authors: Graff G. L. A. , Hudson A. J. , Strickland K. P.
Published: December 2009

In this investigation both ascorbic acid and glycogen were determined in rat gastrocnemius muscle after denervation for times ranging from 12 hours to 60 days. To assess more correctly the changes due to denervation, concentrations per unit weight and content per whole muscle were expressed as a percentage of the corresponding value obtained from the contralateral control. The concentrations of ascorbic acid and glycogen in the normal rat gastrocnemius were, respectively, 2.7 ± 0.1 μg (S.E.M. for 51 animals) and 355 (as a glucose equivalent) ± 15 μg (S.E.M. for 52 animals) per 100 mg wet weight. The concentration of ascorbic acid per unit weight showed significant increase (+ 27%) 36 hours after neurotomy and reached five times the control value 60 days after the denervation. The ascorbic acid content of the whole denervated muscle gradually accumulated to a value of 195% of control at 5 days and then declined to a value of 78% at 15 days and 65% at 60 days. In the later stages of atrophy the losses in ascorbic acid were always less than the losses in muscle mass. The glycogen concentration per unit weight remained essentially unchanged for the first 36–48 hours after neurotomy; it then dropped abruptly to 39% of the original value on the 3rd day and stayed at about this level until the 60th day after denervation. In the first 12 hours there appeared to be a slight rise in the glycogen content of the whole denervated muscle. Subsequently, there was a rapid loss of glycogen from 116% of normal at 24 hours to 35% at 3 days; during the same period of time the loss in muscle mass was only 16%. The loss in glycogen content after 60 days represented 94% of the original amount.The observed initial accumulation of ascorbic acid after denervation may reflect a relative increase in active transport (or in situ synthesis) over breakdown mechanisms. The results reported rule out the possibility that a local deficiency in ascorbic acid per unit weight of muscle is a contributory factor to denervation atrophy and show that there is a continuous local accumulation of ascorbic acid.
IN VIVO INCORPORATION OF P32INTO CHICKEN SERUM PHOSPHOLIPIDS
Authors: Misra U. K.
Published: December 2009

Chicken serum phospholipids have been separated by means of silicic acid column chromatography into phosphatidyl ethanolamine, lecithin, sphingomyelin, and lysolecithin. Their concentration in serum is 12, 68, 10, and 9% respectively of the total of 93.0 mg (average) phospholipid P per 100 ml. The maximum specific activity of serum phospholipids is attained 8 hours after the administration of a dose of inorganic P32. The rate of P32incorporation into serum phospholipids, as studied by means of silicic acid column chromatography, is of the following order: phosphatidyl ethanolamine > lecithin > lysolecithin > sphingomelin.Lysophosphatidyl ethanolamine has been isolated from chicken serum by means of silicic acid impregnated paper chromatography. It represents about 4% of total chicken serum phospholipids. It gave a glycerol to phosphorus ratio of 1.0 and fatty acid ester to phosphorus ratio of 1.03. It also showed a strong hemolytic activity on sheep erythrocytes, and its specific activity 8 hours after the injection of inorganic P32reached about 25% of that for phosphatidyl ethanolamine.
COMBINED EFFECTS OF X-IRRADIATION AND 3′-METHYL-4-DIMETHYLAMINOAZOBENZENE ON LIVER CELL POPULATION
Authors: Webber M. Maini , Stich H. F.
Published: December 2009

Livers of rats were exposed to 950 rads of X-irradiation. The liver cells were then induced to proliferate by the stimulus of partial hepatectomy. The regenerating livers consisted of two cell populations, one of colonies of ceils having normal amounts of DNA and the other having abnormal polyploid and aneuploid cells. Regeneration of the liver is attributed to the colonies with normal cells. When 3′-Me-DAB was fed to the X-irradiated animals, the behavior of these cell populations was reversed. The multiplication of abnormal cells was favored in the presence of the carcinogen. Changes in the percentage of mitotic irregularities, the mitotic rates, and the proportion of various stages of mitosis that resulted in the altered behavior of cell populations are discussed.
ON THE ACTION OF STROPHANTHIN G
Authors: Ahmed K. , Judah J. D.
Published: December 2009

The inhibitory effect of ouabain on Na- and K-activated ATP-ase of rat brain lipoprotein is reduced when the incubation temperature is lowered. The concentration of K+required for maximal ATP-ase activity is also reduced at lower temperatures of incubation. The apparent increase in affinity for K+by the enzyme system at lower incubation temperatures could be responsible for the change in the effectiveness of ouabain. Increase in enzyme protein concentration also reduces the inhibition produced by a given concentration of ouabain, which appears to be due to binding of ouabain by the lipoprotein. From the titration of enzyme by ouabain it is possible to estimate that 5 × 1014molecules of ouabain are taken up per milligram of lipoprotein.
SOME BIOCHEMICAL EFFECTS OF SPORIDESMIN
Authors: Wright D. E. , Forrester I. T.
Published: December 2009

Sporidesmin inhibits in vitro the respiration of guinea pig and sheep liver homogenates in the presence of substrates which require nicotinamide coenzymes for their oxidation. Succinate oxidation was far less sensitive. Similar results were found with mitochondria.Slight swelling and release of 260 mμ absorbing compounds from mitochondria incubated in the presence of sporidesmin were observed. These results are discussed in relation to those reported elsewhere.
DRUG-INDUCED CHANGES IN THE CYTOPLASMIC RIBONUCLEOPROTEIN CONSTITUENTS OF BRAIN TISSUE
Authors: Ghosh J. J. , Datta R. K. , Bhattacharyya K. C.
Published: December 2009

Studies carried out on the properties of isolated ribosomes from drug-treated brain cortex slices indicate that ribosomes from drug-treated tissues are generally more susceptible to breakdown into smaller components such as proteins, nucleic acids, acid-soluble nucleotides, etc. It seems that some factor or factors responsible for the stability of the complex macromolecular structure of ribonucleoproteins of brain tissue are affected as a result of drug treatment. Ribosomal RNA from drug-treated brain tissue has been isolated under standardized conditions and the secondary structures of RNA have been studied by methods involving thermal hyperchromicity and reaction with formaldehyde. This latter study indicates that, during the action of some of these neuropharmacological drugs, the secondary structure of ribosomal RNA of brain tissue is partially lost. The loss in the stability of cytoplasmic ribonucleoproteins in drug-treated brain tissue may partly be due to the disorganization at the level of the secondary structure of the RNA component.
INCORPORATION OF AMINO ACIDS INTO CHICK PROTEINS DURING EMBRYONIC GROWTH
Authors: Taussig Margaret P.
Published: December 2009

Radioactive glycine and methionine were injected into the yolk of 4-day-old embryonated eggs. There was a rapid increase in total incorporated radioactivity with both amino acids. The specific activity of the protein increased until the seventh day, after which time there was a sharp decrease. Radioactivity from DL-methionine-S35was incorporated in larger amounts than from glycine-2-C14. An increase in the proteolytic activity of the yolk with age was demonstrated.
THE PRIMARY STRUCTURE OF THE CYTOCHROMEcFROM VARIOUS ORGANS OF THE HOG
Authors: Stewart J. W. , Margoliash E.
Published: December 2009

The amino acid sequence of hog heart cytochrome c was determined. Like the horse and human heart proteins it was found to consist of a single polypeptide chain 104 residues long with a N-acetylated amino-terminal residue. It differs from horse heart cytochrome c in only three positions, carrying serine instead of threonine at residue 47, glycine instead of lysine at residue 60, and glycine instead of threonine at residue 89. Methods are described for the preparation of cytochrome c, in good yield, from hog liver, kidney, brain, and skeletal muscle. These proteins were all shown to have primary structures identical with that of hog heart cytochrome c, indicating that, notwithstanding differences in the functional activities and embryological origins of the various tissues examined, there is no corresponding change in the structure of cytochrome c. It thus appears likely that the synthesis of all, or at least the bulk, of the cytochrome c is controlled by a single structural gene throughout the body. Minor molecular variants of the protein, which could have been detected at concentrations of 2 to 3% of the entire preparations, were not observed.
THE ENZYMATIC ESTERIFICATION OF ETHANOL WITH FATTY ACIDS
Authors: Newsome W. H. , Rattray J. B. M.
Published: December 2009

Some characteristics of the system present in pancreatin responsible for the enzymatic esterification of ethanol with fatty acids were examined. Definite pH optima were found for different fatty acids in the pH range 5.5–6.1. At a relatively high ethanol level and with a low fixed fatty acid concentration at pH 6.1, the degree of esterification was oleic = linolenic > linoleic > arachidonic > myristic > palmitic > stearic. At various acid concentrations the same general order of specificity was observed but to differing extents. The physical state of dispersion of the fatty acid in the incubation medium appeared to be a major factor governing the fatty acid specificity for esterification of ethanol. Evidence for the possible occurrence of more than one enzyme activity functioning on fatty acid substrate in different dispersion states was obtained and discussed.
SPECIES DIFFERENCES AND PANCREATIC LOCALIZATION OF 1-AMINOCYCLOPENTANE-C14-CARBOXYLIC ACID
Authors: Sherman F. C. , Paredes A. M. , Chambers D. A. , Nardi G. L.
Published: December 2009

Rabbits, mice, and dogs were injected with 1-aminocyclopentane-C14-carboxylic acid and the distribution of the drug was studied by tissue analysis. Concentration of the isotope was observed in mouse pancreas but not in that of dogs and rabbits.
METABOLISM OF ORGANOPHOSPHORUS INSECTICIDES: II. METABOLISM OF O,O-DIMETHYL-2,2,2-TRICHLORO-1-HYDROXYETHYL PHOSPHONATE (DIPTEREX) IN MAMMALIAN NERVOUS TISSUE AND KINETICS INVOLVED IN ITS REACTION WITH ACETYLCHOLINE ESTERASE
Authors: Hassan A. , Zayed S. M. A. D. , Abdel-Hamid F. M.
Published: December 2009

The metabolism of P32-labelled Dipterex in rat brain homogenates has been investigated. The presence of four metabolites, three acidic and one nonacidic, has been demonstrated. Monodemethylated Dipterex and monomethylphosphate contributed to 37% and 7% of the total metabolite output respectively. The third acidic metabolite (16%) is believed to be 2,2,2-trichloro-1-hydroxyethyl phosphonic acid. The nonacidic compound has not yet been identified. The reaction of Dipterex with acetylcholine esterase has been found to be of bimolecular nature.
PHOSPHONOLIPIDS: IV. SYNTHESIS OF PHOSPHONIC ACID ANALOGUES OF L-α-CEPHALINS
Authors: Baer Erich , Sarma G. Raghupati
Published: December 2009

The synthesis of phosphonic acid analogues of L-α-(distearoyl)cephalin and L-α-(dimyristoyl)cephalin is described. They were obtained by phosphonylating D-α,β-distearin and D-α,β-dimyristin with 2-phthalimidoethylphosphonic acid monochloride and triethylamine, and removing the protective phthaloyl group of distearoyl and dimyristoyl L-α-glyceryl-(2-phthalimidoethyl)phosphonate by hydrazinolysis.
ISOLATION OF ESTRADIOL-17β FROM HEN'S URINE AND ITS CHARACTERIZATION AS THE CRYSTALLINE 3-METHYL ETHER
Authors: Hertelendy F. , Taylor T. G. , Mathur R. S. , Common R. H.
Published: December 2009

Estradiol-17β-3-methyl ether has been prepared in crystalline form from the phenolic steroid fraction of hen's urine and characterized by its melting point, the melting point of its acetate, and the chromatographic behavior of the crystalline material, of its acetate, and of its benzoate in each of three different thin-layer chromatographic systems.The method of Brown has been modified to render it more specific for the determination of estradiol-17β in hen's urine. Values for the estradiol-17β content of the urine of laying and nonlaying hens are reported.
EFFECT OF NUTRITIONAL STATE ON HORMONAL REGULATION OF LIVER ENZYMES
Authors: Weber G. , Singhal R. L. , Srivastava S. K.
Published: December 2009

The ability of enzyme-forming systems to meet the challenge of starvation and produce vital metabolites for maintaining homeostasis was studied. The preferential maintenance of hepatic gluconeogenic enzymes in starvation can be blocked by hypophysectomy and also by inhibitors of protein synthesis, actinomycin and ethionine. Starvation, cortisone, and triamcinolone were capable of inducing a pronounced increase in the incorporation of orotate into hepatic RNA. Actinomycin administration blocked the starvation- and steroid-induced rise in RNA specific activity. The glucocorticoid hormone induced increase in enzyme biosynthesis and the rise in free amino acid level were rapidly blocked by actinomycin and ethionine and were affected also by starvation.In the adaptation of the organism to acute starvation the hepatic enzyme-forming systems are regulated by the interplay of two hormones to produce a preferential maintenance of key gluconeogenic enzymes. Insulin, a suppressor of biosynthesis of gluconeogenic enzymes, is known to decrease in amount during starvation. Under the same circumstances glucocorticoid hormones, which are inducers of the biosynthesis of gluconeogenic enzymes, are present and thought to be responsible for the preferential maintenance of key gluconeogenic enzyme activities, thus ensuring adequate blood glucose levels in starvation.
PURIFICATION AND PROPERTIES OF A RIBOSOMAL PEPTIDASE FROM ESCHERICHIA COLI B
Authors: Tsai C. S. , Matheson A. T.
Published: December 2009

A leucylglycine-splitting enzyme from E. coli ribosomes has been purified and its properties studied. The ribosomal proteins were solubilized by disrupting the ribosomal particles in 1 M Tris. As purification proceeded the ionic strength required to keep the proteins in solution steadily decreased until, in the later stages, the enzyme could be fractionated on ion-exchange columns at low ionic strengths. The ribosomal peptidase requires K+or Cs+and Mn2+or Mg2+for full activity and is inhibited by Na+and Li+. It is completely inhibited by EDTA. The enzyme, which is a basic protein with no absorbancy maximum in the 280 mμ region of the spectrum, has a broad optimum pH range from 7.5 to 9.2. On small-scale preparations over a 1000-fold purification has been obtained.
FURTHER STUDIES OF CHANGES IN PLASMA PROTEINS IN AVIAN ERYTHROBLASTOSIS: I. TWO-DIMENSIONAL STARCH GEL ELECTROPHORESIS
Authors: Merriman Mohendra
Published: December 2009

Plasma protein changes in avian erythroblastosis previously studied with paper and starch gel electrophoresis have now been examined with a two-dimensional technique combining the two methods. The differences affect chiefly one zone which migrates in the α-globulin region.
INHIBITION OF RIBONUCLEOSIDE METABOLISM IN EHRLICH ASCITES TUMOR CELLS BY PURINE ANALOGUE RIBONUCLEOSIDES
Authors: Paterson A. R. P. , Simpson A. I.
Published: December 2009

Several aspects of the metabolism of inosine and uridine by Ehrlich ascites carcinoma cells in vitro have been found to be inhibited by ribonucleoside derivatives of four purine analogues. The synthesis of both inosine and uridine by intact tumor cells was profoundly inhibited in the presence of 6-methylmercaptopurine ribonucleoside. Also inhibited were inosine and uridine cleavage, and the exchange of isotope between these ribonucleosides and the corresponding C14 labelled bases. These reactions, however, were not inhibited when they took place in broken-cell preparations. Similarly, inosine metabolism in intact cells (but not in broken cells) was profoundly inhibited by three related compounds: the ribonucleosides of the 6-chloro, 6-methylmercapto, and 6-propylmercapto derivatives of 2-aminopurine.
AMINOIMIDAZOLE RIBONUCLEOTIDE CARBOXYLASE: PARTIAL PURIFICATION AND PROPERTIES
Authors: Ahmad Fazal , Missimer Patricia , Moat Albert G.
Published: December 2009

The enzyme aminoimidazole ribonucleotide carboxylase has been partially purified from chicken livers. A somewhat higher degree of purification was achieved with pigeon liver acetone powder as the starting material. This enzyme carboxylates the ribonucleotide but cannot use the free base, aminoimidazole, as its substrate. An investigation of the requirements for optimal activity reveals that magnesium ions are essential. Inhibition by a variety of reagents which react with sulfhydryl groups indicates their importance in the fixation of carbon dioxide to aminoimidazole ribonucleotide. An exhaustive search revealed that none of the B-vitamin cofactors play a role in this reaction. The lack of an energy requirement, e.g. ATP, for activity and the nucleophilic nature of the amino-substituted ring suggest that the carboxylation of aminoimidazole ribonucleotide proceeds via a direct enzyme-mediated reaction involving Mg++ions and active sulfhydryl groups.
RELEASE OF ENZYMES FROM RAT LIVER MITOCHONDRIA BY FREEZING
Authors: Lusena C. V.
Published: December 2009

Glutamate and 3-hydroxybutyrate dehydrogenase activities were used to estimate freezing damage to mitochondria.Freezing damage occurred in mitochondria by two steps: one was rapid and involved changes in membrane structure to expose 3-hydroxybutyrate dehydrogenase with concomitant release of glutamate dehydrogenase; the other was a slow extraction of glutamate dehydrogenase. The effect of freezing and thawing was very similar to the effect of exposure to high sucrose concentration and redilution. The data indicate that freezing temperature not only determined the sucrose concentration but also regulated the diffusion of sucrose. A combination of effects, of sucrose concentration and of diffusion, resulted in maximum damage at about −15 °C, while below −40 °C no damage was detectable.
NUCLEIC ACID OF MURINE ENCEPHALOMYELITIS VIRUS PHYSICAL AND CHEMICAL STUDIES
Authors: Moscarello M. A.
Published: December 2009

Studies concerning some of the chemical and physical properties of ribonucleates isolated from highly purified encephalomyocarditis virus are presented. Base analyses were performed by both an alkali degradation procedure and hydrolysis with snake venom phosphodiesterase. In addition to the four common bases, adenine, guanine, cytosine, and uracil, several minor components have been found in both the alkali and diesterase hydrolysates. Since much of the work was done with P32-labelled ribonucleates, it has not been possible to identify any of the minor components.Ultracentrifugal studies performed in the Spinco model E analytical centrifuge revealed a single peak corresponding to a S20, wof 3.2. This low S20, wwas confirmed by centrifugation in a sucrose gradient. These results, in addition to those obtained by column chromatography, have been interpreted as being indicative of a considerable degree of fragmentation, probably as a result of the presence of trace amounts of ribonucleases or hydroxyl ions during the extraction procedure.
LA PHOSPHATASE ACIDE DU GERME DE BLÉ: ANALYSE CHROMATOGRAPHIQUE
Authors: Brouillard Jacques , Ouellet Ludovic
Published: December 2009

Chromatographic analysis of acid phosphatase of wheat germ shows that this enzyme exists as four different, active, and easily separable molecular forms. The four fractions also hydrolyze esterase substrates. All four isozymes are yellow, and the visible spectra of three of them are given. Following a previous observation, we confirmed the presence of iron in the enzyme, presumably as Fe+++.
PREPARATION OF SPECIFICALLY LABELEDD-FRUCTOSE-14C
Authors: White G. A. , Robinson J. R. , Unwin C. H.
Published: December 2009

A method is described whereby specifically labeled D-fructose-14C can be prepared easily and in high yield (95%) from specifically labeled D-glucose-14C by the action of purified bacterial sorbitol dehydrogenases.
THE OXIDATION OF SKATOLE WITH POTASSIUM PERSULFATE
Authors: Heacock R. A. , Mahon M. E.
Published: December 2009

The oxidation of skatole with potassium persulfate has been shown to produce a mixture of potassium 4-, 5-, 6-, and 7-skatolyl sulfates, together with 3-methyl-oxindole, o-aminoacetophenone, o-formamidoacetophenone, and a number of unidentified products. All four isomeric skatolyl hydrogen sulfates can be hydrolyzed to the corresponding hydroxyskatoles by hot dilute mineral acid; however, only the 5-, 6-, and 7-isomers were hydrolyzed by "glusulase", a commercially available sulfatase preparation.
THE EFFECTS OF CHOLINE DEFICIENCY AND CHOLINE RE-FEEDING UPON THE METABOLISM OF PLASMA AND LIVER LIPIDS
Authors: Haines D. S. M.
Published: December 2009

The disturbance in lipid metabolism caused by deficiency of dietary choline in rats was investigated with H3-palmitic acid as a tracer. The incorporation of radioactivity into blood triglycerides, as compared to that in choline-supplemented controls, showed a striking decline in rats taken at intervals during the development of choline deficiency. This was partially corrected by choline re-feeding for 2 days and was normal after 4 days of choline re-feeding. Both the total amounts and the radioactivities of phosphatidyl choline in the liver and total phospholipids in the plasma were reduced in choline deficiency and were restored by choline re-feeding, whereas phosphatidyl ethanolamine in the liver was not affected. The findings confirm that the fatty liver of choline deficiency is the result of an impairment in the transport of triglyceride from the liver, and support the hypothesis that it occurs because of a restriction in the synthesis of phosphatidyl choline which is required for lipoprotein formation.A marked reduction in the transformation of14C-ethanolamine into phosphatidyl choline was evident in choline deficiency, but most of the increase in liver phosphatidyl choline which occurred subsequent to choline re-feeding appeared to be from synthesis by the direct (CDP-choline) pathway.
EVIDENCE OF A MICROSOMAL FACTOR REQUIRED FOR IN VITRO DEVELOPMENT OF PSEUDO-TRYPTOPHAN SYNTHASE ACTIVITY BY EXTRACTS OF NEUROSPORA CRASSA
Authors: Wainwright S. D.
Published: December 2009

Extracts of conidia of the td3mutant strain of Neurospora crassa did not develop pseudo-tryptophan synthase enzyme activity under conditions leading to formation of the activity by equivalent extracts of the wild type strain. The defect in extracts of the td3mutant appears to be located in the microsome fraction. The latter is unable to interact effectively with a component of the td3mutant "post-microsome" fraction which will support in vitro development of the enzymic activity when supplemented with microsomes from other strains of N. crassa.
ALDOSTERONE AND CORTICOSTERONE PRODUCTION BY RAT ADRENAL SLICES AS A FUNCTION OF THE TIME OF INCUBATION
Authors: Laplante C. , Stachenko J.
Published: December 2009

Some factors affecting steroid production by rat adrenals in vitro have been studied. Aldosterone production by normal glands increases linearly for at least 20 hours of incubation, whereas corticosterone production reaches a plateau after 4 hours. Aldosterone production by adrenals from rats kept on 1% NaCl as drinking fluid for 8 days does not increase after the second hour of incubation. Varying the volume of Krebs–Ringer bicarbonate medium (containing a given amount of tracer 4-14C-progesterone) does not alter the endogenous production of aldosterone or corticosterone, but the specific activity of these compounds decreases as the volume of Krebs–Ringer bicarbonate increases. The significance of these findings is discussed.
ENZYMES OF PENTOSE BIOSYNTHESIS: I. SEPARATION OF PENTOSE CYCLE ENZYMES OF ESCHERICHIA COLI
Authors: Yaphe W. , Christensen David D. , Biaglow J. E. , Jackson M. Alden , Sable Henry Z.
Published: December 2009

A study of the enzymes of the pentose cycle in Escherichia coli has been undertaken. Procedures are reported for separating the cell extract into fractions containing transketolase, D-xylulose-5-phosphate-3-epimerase, and transaldolase and phosphoribose isomerase. Cross contamination was small enough and yields of enzymatic activity were adequate to make the fractions usable for further purification steps. Preliminary results of the further purification of the enzymes, some properties of the enzymes, and a number of problems in enzyme assay are discussed.
FACTORS INFLUENCING THE UTILIZATION OF REDUCED NICOTINAMIDE ADENINE DINUCLEOTIDE BY PIGEON HEART MITOCHONDRIA
Authors: Blanchaer Marcel C. , Lundquist Carl-Göran , Griffith Thomas J.
Published: December 2009

Pigeon heart mitochondria that were studied exhibited ADP:O and respiratory control ratios of 2.3–3.1 and 6–20 respectively with glutamate as substrate. This coupled respiration of glutamate was reversibly inhibited by ATP. In polarographic and photometric experiments at 28° in a medium containing 0.23 M mannitol, 0.07 M sucrose, 0.02 M Tris, and 0.02 mM EDTA at pH 7.2 such mitochondria oxidized 15–150 μM NADH with essentially zero order kinetics and an apparent Kmof approximately 4 μM. NADH oxidation, which was not coupled to phosphorylation, was increased 50% by the addition of 5 mM orthophosphate (Pi) but was inhibited by albumin, NAD, ATP, and ADP. The effect of NAD became marked only at concentrations of 2–5 mM. However, ATP in concentrations (5–10 mM) similar to those found in heart, inhibited by 50–75% the oxidation of physiological levels (~ 10 μM) of NADH. These and other findings are compatible with the view that the oxidation of cytoplasmic NADH is a normal property of heart mitochondria, and that the control of this process by changes in the intracellular levels of ATP and Pimay influence myocardial carbohydrate utilization.
A KINETIC STUDY OF THE DEAMINATION OF SOME ADENOSINE ANALOGUES: SUBSTRATE SPECIFICITY OF ADENOSINE DEAMINASE
Authors: York J. Lyndal , LePage G. A.
Published: December 2009

The kinetic constants Kmand Vmaxwere determined for the deamination by adenosine deaminase of a series of analogues of adenosine containing "fraudulent" sugars. The configuration of the 2′-hydroxyl was found to be important for the binding of enzyme and substrate. The largest effect of changes in sugar structure was on the rate of breakdown of the enzyme–substrate complex to form products, i.e. Vmax. The nature of the configuration in the 3′-position was not important if the 2′-hydroxyl was trans to the glycosidic linkage; however, if the steric arrangement of the 2′-hydroxyl was cis to the glycosidic linkage, then Vmaxshowed a marked dependence on the nature of the 3′-substituent and its configuration. For instance, Vmaxvalues were for arabinosyl adenine < 3′-deoxyarabinosyl adenine <lyxosyl adenine. 6-N-methyladenosine was found to be a competitive inhibitor of adenosine deaminase, with a Kiof 2 × 10−6M.
THE BIOLOGICAL DIFFERENTIATION OF 99Mo AND 99Tcm IN RABBITS AND ITS EFFECT ON THE GAMMA-COUNTING RATE OF PLASMA SAMPLES
Authors: Robinson G. A. , McCarter A.
Published: December 2009

Thirty-one rabbits were each injected intravenously with 250–450 μcuries molybdate-99Mo in transient equilibrium with 99Tcm. Blood samples were taken at intervals from 0.5 to 48 hours after the isotope injections. The gamma-counting rate of the blood plasma was recorded at 13 intervals during the 96 hours subsequent to the bleedings. Gamma curves, uncorrected for nuclear decay, were biphasic for 151 of the 194 samples. Recognizable first components (mean half-life ± s.e.m., 6.12 ± 0.10 hours). represented the buildup of 99Tcm to equilibrium levels in 53 samples (38 of these from rabbits fed on control diets) and decay of "excess" 99Tcm in 101 others (65 for rabbits fed on diets containing 0.4% Na2MoO4). The second components (mean half-life 65.9 ± 1.1 hours) represented a condition of transient equilibrium between 99Mo present in the samples at time of bleeding and the daughter nuclide. Biological differentiation of 99Mo and 99Tcm as observed in this study indicated that the indiscriminate measurement of gamma emissions for 99Mo-containing systems may give apparent 99Mo concentrations 0.57–2.31 times the actual values. Counting of either the total beta emission or a specific 99Mo gamma energy is recommended when the measurement of 99Mo is attempted.
DEGRADATION OF THE CARBON SKELETON OF GLUTAMIC ACID
Authors: Finlayson A. J.
Published: December 2009

Glutamic acid-2-14C was degraded in such a way that its individual carbon atoms were separately recovered as carbon dioxide. No evidence was found for any rearrangement of the carbon skeleton resulting from the reactions.
THE EFFECT OF LETHAL DOSES OF X-IRRADIATION ON THE ENZYMATIC ACTIVITY OF MITOCHONDRIAL CYTOCHROMEc
Authors: Scaife J. F.
Published: December 2009

The coupling of the tetrazolium salts triphenyltetrazolium chloride and nitro-blue tetrazolium to the electron transport chain in mitochondria of thymus, spleen, liver, kidney, and Ehrlich ascites carcinoma cells has been studied with several substrates. In experiments on succinate–triphenyltetrazolium chloride reductase activity it has been possible to demonstrate a radiation lesion in the electron transport chain of mitochondria from thymus and spleen, but not in those from other tissues. This lesion is evident 4 hours after 25 rad of whole-body irradiation, or earlier with higher doses. It is not prevented by the prior administration of aminoethylisothiouronium bromide, serotonin, vitamin K1, or vitamin E, but is reduced by anoxic conditions.Lower levels of cytochrome c are found in irradiated mitochondria isolated from thymus, and the radiation lesion is believed to be produced by loosening the binding of cytochrome c to the mitochondrial membrane after X-irradiation. Decreased levels of ATP occur in thymus, spleen, and ascites cells following irradiation.
STUDIES ON PLASMINOGEN: IV. ALTERATION OF BOVINE AND HUMAN PLASMINOGENS DURING ISOLATION
Authors: Chan John Y. S. , Mertz Edwin T.
Published: December 2009

Bovine and human plasminogen preparations were analyzed by starch-gel electrophoresis at pH 2.5 and 0.10 ionic strength. The bands were activated with urokinase and the proteolytic and esterolytic activities measured. Bovine euglobulin contains one plasminogen band, B-1. Plasminogen prepared from bovine euglobulin by continuous electrophoresis at pH 3.5 contains B-1 and a faster plasminogen band, B-2. B-1 and B-2 are also found in bovine plasminogen prepared by DEAE-cellulose chromatography. All three preparations on activation give the same two plasmin bands on starch gel. Human euglobulin also contains two active plasminogen bands H-1 and H-2. Plasminogen prepared from human euglobulin by continuous electrophoresis at pH 3.5 contains H-1, H-2, and a faster minor plasminogen band, H-3. All highly purified human plasminogens derived from Cohn fraction III contain either H-3 as a major band and an additional plasminogen band, H-4, or only H-3, but no H-1 and H-2. On activation with urokinase or streptokinase, human plasminogen preparations give one or two plasmin bands. It is concluded that bovine B-2 and human H-3 and H-4 are altered forms of euglobulin plasminogen created during isolation procedures. Essentially pure human H-3 can be prepared by continuous electrophoresis from Cutter plasminogen.
STUDIES ON PLASMINOGEN: V. PURIFICATION OF BOVINE AND HUMAN PLASMINOGENS BY SEPHADEX CHROMATOGRAPHY
Authors: Chan John Y. S. , Mertz Edwin T.
Published: December 2009

Purified euglobulins prepared from bovine and human serum were fractionated by Sephadex column chromatography at pH 3.5. The products obtained were purified further by phosphate precipitation (bovine) or lysine solubilization (human) to yield final products with activities comparable to those prepared by the continuous-flow electrophoresis method. Plasminogen from Cohn fraction III-4 was also purified. The method yields preparations from serum which contain essentially no altered plasminogen. The specific activities, the starch-gel patterns, the molecular weights, and the recoveries of the purified bovine and human plasminogen preparations are reported and discussed.
STUDIES ON PLASMINOGEN: VI. ACTIVATION PRODUCTS OF BOVINE AND HUMAN PLASMINOGENS
Authors: Chan John Y. S. , Mertz Edwin T.
Published: December 2009

Activated, purified bovine plasminogen, when fractionated on a Sephadex column, revealed four major protein peaks. Bovine plasmin I and plasmin II were found under peak II and peak III, respectively. Highly potent bovine plasmin II was recovered from peak III. Activated human plasminogen, when fractionated by the same technique, yielded an elution curve similar to that of the nonactivated sample. The pathway of the breakdown of bovine plasminogen upon activation with urokinase was studied by starch-gel electrophoresis and Sephadex chromatography. It is suggested that native bovine plasminogen is first converted to an altered plasminogen, which is then converted to plasmin I, plasmin I is then converted to plasmin II, and plasmin II to peptide A. The molecular weights of plasmin I, plasmin II, and peptide A were estimated by the Sephadex method to be 8.0 × 104, 6.2 × 104, and 4.3 × 104, respectively.
HETEROGENEITY AND DIFFERENTIAL FRAGILITY OF RAT LIVER MITOCHONDRIA
Authors: Lusena C. V. , Depocas Florent
Published: December 2009

Five fractions (I–V) of intact mitochondria were obtained from rat liver by differential centrifugation during isolation. They represented respectively 4, 9, 64, 11, and 11% of the total mitochondrial protein. No striking differences between mitochondria sedimented at low speed (fraction I) and those sedimented at high speed (fraction V) were seen by electron microscopy. In all samples glutamic dehydrogenase (GD) specific activity was the same after deoxycholate treatment and less than 1% of the total activity could be detected in the fresh fractions. Overnight freezing at −5 °C of fractions I, III, and V followed by thawing at 37 °C liberated 25, 11, and 6% respectively of the total GD activity. The greater fragility of fraction I relative to that of fraction V was also apparent in the phase-contrast microscope during warming to room temperature; lysis occurred in 10 minutes in fraction I and in 1 hour in fraction V. The distribution of GD activity after centrifugation on sucrose density gradients indicated that partial disruption of the mitochondria had occurred in decreasing degree from fractions I to V. The different fragilities of the fractions in vitro did not reflect different lability in vivo since all fractions had the same rates of turnover as measured after they were labeled with14C acetate. The results are discussed in terms of heterogeneities observed by other methods.