bluuebunny/crossref_metadata_2025 huggingface dataset:
Biochemical changes in progressive muscular dystrophy. VII. Studies on the biosynthesis of protein and RNA in various cellular fractions of the muscle of normal and dystrophic mice
Authors: Srivastava Uma
Published: December 2009

Protein nitrogen content, RNA concentration, and in vivo incorporation of L-[U-14C]leucine into protein and of [2-14C]uridine into RNA of homogenate and various fractions of muscle of normal and dystrophic mice were measured at various stages of the disease. Protein nitrogen content was always lower in dystrophic than in normal muscle, and this became more pronounced with the progress of the disease. Most of the decrease was due to loss of proteins from the myofibrils. RNA content increased in the homogenate, nuclei–myofibrils, supernatant, and microsomes of dystrophic muscle. In the mitochondria of dystrophic muscle, no change was noted compared to controls. The ratio of RNA content to protein in the homogenate, nuclei–myofibrils, supernatant, and microsomes was also greater in dystrophic muscle. It was not changed in dystrophic muscle mitochondria. Incorporation of L-[U-14C]leucine into proteins of dystrophic muscle homogenate and various fractions also increased to variable degrees over that in the controls. It was further observed that mitochondrial and microsomal protein incorporate L-[U-14C]leucine in dystrophic muscle at an increased rate but the disappearance of 14C was even greater, compared to controls.In vivo incorporation of [2-14C]uridine into RNA of dystrophic muscle increased at 30 days', remained the same at 60 days', and declined at 90 days' duration of the disease. Similar results were also obtained in the nuclei–myofibrillar fraction of dystrophic muscle. In all other fractions an increase was noted in incorporation in dystrophic muscle. The incorporation of [2-14C]uridine into RNA in supernatant and microsomes was higher in dystrophic muscle but the disappearance of 14C was greater, compared to controls. It is quite evident in the microsomal fraction at 90 days, where no change in the incorporation is noted in normal and dystrophic animals.
Purification of human 19S thyroglobulin by gel filtration
Authors: Mouriz Joaquin , Stanbury John B.
Published: December 2009

The presence of thyroglobulin in the main peak of a Sephadex G-200 fractionation of a saline extract of human thyroid was detected by Ouchterlony double immuno-diffusion plates against rabbit antihuman thyroglobulin serum.Refiltration of thyroglobulin pooled from the first part of the main peak did not yield a pure native thyroglobulin. A pure 19S component could only be obtained by pooling the effluent corresponding to the descending slopes of the thyroglobulin peaks obtained on the one hand by filtration of the saline extracts, or on the other by refiltration of the effluent corresponding to the ascending slopes of the first filtrations.
Chondroitin sulfate changes in puppy rib cartilage during the period of calcification
Authors: Bowness J. M. , Jacobs M.
Published: December 2009

Using a single litter of seven puppies, it was found that in the period (13–30 weeks of age) when calcification was occurring in most of the ribs there was a change in the extractability of the chondroitin sulfate in this tissue. There was a decrease in the amount of chondroitin sulfate which could be extracted by homogenizing with water and an increase in the amount which was extracted subsequently by homogenization with alkali. This change was not due to binding of chondroitin sulfate to solid mineral matter because it was found also in a single uncalcified rib from an older puppy in which all but the first two anterior ribs were heavily calcified. It was also found when EDTA was used to extract the solid mineral matter. Measurement of specific activities after injection of radioactive sulfate showed that there was little change in the relative rates of synthesis of the water-soluble and water-insoluble chondroitin sulfate fractions as the age of the puppies increased. This leaves a change in the relationship of protein to chondroitin sulfate in complexes of the two as the most likely explanation for the observed change in extractability.
Mutation de dépendance vis-à-vis de la streptomycine induite par le méthanesulfonate d'éthyle chez Escherichia coli
Authors: Verly W. G. , Petitpas-Dewandre A. , Barbason H.
Published: December 2009

not available
Isolation of the γc-globulin of bovine cerebrospinal fluid
Authors: MacPherson Catherine F. C. , Feldmuller François
Published: December 2009

The γc-globulin of bovine cerebrospinal fluid (CSF) was isolated in immunologically pure form from the globulin fraction of CSF or milk whey by gel filtration on Sephadex G-75. The globulin fraction was obtained by precipitation with sodium or ammonium sulfate rather than by DEAE chromatography because salt precipitation resulted in greater yields of the γc-globulin. When the protein was isolated from bovine colostral whey, about 90% of the immunoglobulin G (IgG) globulin was removed by a preliminary filtration of the whey on Sephadex G-75. The fraction containing the γc-globulin admixed with IgG globulin was then re-chromatographed on Sephadex G-75 to remove the IgG globulin. On gel filtration through a column of Sephadex G-75 that had been calibrated with proteins of known molecular weight, the elution volume of the γc-globulin corresponded to a molecular weight of 30 000. Different lots of γc-globulin that contained no detectable impurities by gel-diffusion tests were compared on a weight basis by a quantitative immunochemical method, and were found to have equal immunological activity.
Studies on the mechanism of action of ethylene. I. The effects of ethylene on mitochondria prepared from bean cotyledons
Authors: Olson A. O. , Spencer Mary
Published: December 2009

For investigations of the possible mechanism of action of ethylene, intact mitochondria with respiratory control were prepared from bean cotyledons of various ages. Ethylene treatment resulted in an increase in the rate of mitochondrial volume change caused by adenosine diphosphate or adenosine triphosphate, but was without effect on spontaneous changes or those mediated by phosphate or calcium ions. This suggested that ethylene affects an enzyme with which the nucleotides react and which is associated with mitochondrial volume changes. Such an enzyme is mitochondrial adenosine triphosphatase, and it was found that ouabain, known to be an inhibitor of this enzyme in some cotyledons, prevented the response to ethylene.
Possible isoenzymes of monoamine oxidase in rat tissues
Authors: Kim H. C. , D'Iorio A.
Published: December 2009

The solubilized monoamine oxidase activity of rat liver, kidney, and brain can be separated into several bands by cellulose polyacetate membrane electrophoresis. Four such bands of activity are found in the whole liver homogenate while mitochondrial and microsomal fractions appear to have two. The activity of these bands has been assayed using three different substrates, isoamylamine, tyramine, and benzylamine. The solubilized mitochondrial monoamine oxidase activity of kidney and brain when submitted to electrophoresis is found to separate in two fractions. There is some small but consistent difference of distribution of activity when using different substrates.
The relationship of protein synthesis to the secretion of the lipid moiety of low density lipoprotein by the liver
Authors: Buckley J. T. , Delahunty T. J. , Rubinstein D.
Published: December 2009

The release of low density lipoproteins by the rat has been studied in vivo and in perfused liver, with the use of leucine-1-14C and palmitate-9,10-3H as precursors. There is a delay in the time of appearance of the labelled lipoprotein in the perfusate, the delay being longer for the 14C-protein than the 3H-lipid moiety. In vivo there is a difference of [Formula: see text] h between the times of maximum appearance of labelled lipid and protein, the former appearing first. These delays are not due to a slow entry of the leucine-14C into the amino acid pool, since no delay is seen when incorporation of the isotope into tissue proteins of perfused liver is studied. When bovine serum albumin replaces plasma in the perfusing medium there is a marked decrease in the release of labelled lipoprotein lipid, although net glyceride release and 14C incorporation into lipoproteins is not affected. This suggests an exchange between liver and serum lipids. Puromycin inhibits both the release and the exchange of lipid in the perfused liver system. In the in vivo experiments, puromycin virtually inhibits the release of 14C-labelled lipoprotein, while the inhibition of 3H-labelling, although always noted, is more variable in degree. A model for lipoprotein secretion, based on these results, is discussed.
Influence of several drugs on the in vivo and in vitro activity of mammalian hepatic azo-reductase
Authors: Burba John V.
Published: December 2009

The ability of a variety of drugs to influence liver azo-reductase activity of rabbits, rats, and guinea pigs in vitro was determined. Only nitrofurantoin showed a marked stimulatory activity in the three species. There was no appreciable inhibitory activity with any of the drugs tested. Determination of azo-reductase activity in vivo after pretreatment of the animals with phenobarbital and nitrofurantoin showed that there was an appreciable increase only in the azo-reductase activity of rats with phenobarbital, and only rabbits showed a marked decrease in azo-reductase activity with nitrofurantoin. Under the same conditions there was an appreciable increase in the excretion of N-acetylated sulfanilic acid by phenobarbital-pretreated rats and guinea pigs, while with nitrofurantoin rabbits showed an increase and rats a large decrease in the excretion of N-acetylated sulfanilic acid.
Fish liver pyrimidine deoxynucleoside phosphorylase and deoxyribosyltransferase
Authors: Tarr H. L. A. , Roy Joan E. , Yamamoto M.
Published: December 2009

A pyrimidine deoxynucleoside phosphorylase, which also possessed deoxyribosyltransferase activity, was purified about 89-fold from trout liver with an average recovery of 67%. Starch-gel electrophoresis showed that four proteins were present, one of which possessed both activities. The phosphorylase utilized uracil, thymine, and 5-halogen-substituted uracils, but not cytosine, adenine, or hypoxanthine in presence of deoxyribose 1-phosphate. Deoxyuridine, thymidine, and the deoxynucleosides of the 5-halogen-substituted uracils, but not uridine, deoxycytidine, deoxyadenosine, deoxyinosine, or deoxyguanosine, were substrates for the reverse reaction. The enzyme possessed a much higher affinity for deoxyuridine than for thymidine, the Km values being 1.7 × 10−3 M and 1 × 10−2 M respectively. The optimum pH was 6.2. The enzyme was destroyed by freezing, and was rapidly inactivated at 45° and by dialysis. It was very unstable in absence of 2-mercaptoethanol and fairly unstable in absence of orthophosphate. Deoxyuridine phosphorolysis was inhibited noncompetitively by thymine and uracil. The transferase exhibited no sharp pH optimum and utilized the same substrates as did the phosphorylase. The ratio transferase/phosphorylase remained approximately constant (4.0) during purification. The enzyme formed 3-deoxyribosylxanthine in small amounts from xanthine plus deoxyribose 1-phosphate and from deoxyuridine plus xanthine.
Fish muscle glycogen phosphorylase
Authors: Yamamoto M.
Published: December 2009

Glycogen phosphorylase b was purified 70- to 90-fold from skeletal muscle of rainbow trout (Salmo gairdneri). The purified enzyme exhibited maximal activity near pH 6.8 at 37°. Of several 5′-nucleotides tested, only 5′-AMP caused stimulation of phosphorylase b. The Km value for glucose-1-phosphate was 10–15 mM, and for 5′-AMP, 0.2–0.4 mM. Glucose (25 mM) and ATP (5 mM) were both inhibitory, but glucose-6-phosphate (5 mM) had no effect. Inactive trout muscle phosphorylase was converted to the active form in vivo by subjecting a fish to physical exercise. The conversion of fish muscle phosphorylase b to a was also catalyzed in vitro with purified rabbit muscle phosphorylase b kinase in the presence of ATP and Mg++. Evidence is presented to indicate the presence of phosphorylase b kinase and phosphorylase phosphatase in trout skeletal muscle.
Further studies on ε-lysine acylase. The ω-N-acyl-diamino acid hydrolase activity of avian kidney
Authors: Leclerc Jean , Benoiton Leo
Published: December 2009

ω-N-Acyl-diamino acids have been tested as substrates for ε-lysine acylase from animal sources. Chicken and pigeon kidney enzyme preparations hydrolyzed derivatives of lysine homologues as well as of lysine, the best substrates tested being ε-N-propionyl-lysine and ε-N-propionyl-ornithine. A modified procedure for purifying the enzyme from rat and hog kidney is presented. Some of its properties are different from those previously reported.
Pancreatic insulinase and its inhibition by the A and B chains and partial hydrolysate of insulin
Authors: Tasaka Yoshimasa , Campbell James
Published: December 2009

Insulin was destroyed rapidly by insulinase of rabbit pancreatic extract. The activity was enhanced threefold by glutathione, and was inhibited by the sulfhydryl poisons, mercuric chloride, cupric sulfate, and p-chloromercuribenzoate. The insulinase was also strongly inhibited by low concentrations of acid hydrolysate of insulin and by the oxidized forms of the B and the A chains of insulin.
The role of ammonium sulfate precipitation in the removal of substances which interfere with enzymatic hydrolysis of conjugated estrogens in pregnancy urine
Authors: Cohen Saul L.
Published: December 2009

Precipitation of the conjugated estrogens from pregnancy urine by 70% (w/v) (NH4)2SO4 was found to leave urinary substances in the supernatant which interfere with the assay following hydrolysis with enzymes (Ketodase and Glusulase). This removal of enzyme inhibitors is associated with a decrease in optimal pH for enzymic hydrolysis as well as with a reduction in the minimum amount of enzyme required to effect a maximum hydrolysis. One of the inhibitors removed is saccharolactone that may be present. An additional removal of enzyme inhibitors, with a further reduction in optimal pH, is effected by extraction of a solution of the (NH4)2SO4 precipitate by the technique of Kellie. These purification procedures result in an optimal pH for enzymatic hydrolysis equivalent to that reported for pure conjugates, and a 5- to 10-fold reduction in the minimum amount of enzyme required to effect a maximum hydrolysis. Propylene glycol, unlike its effect on phenolphthalein and pregnanediol glucuronides, has an inhibitory effect on the enzymic hydrolysis of estriol glucuronide.
Evidence for albumin – Cu(II) – amino acid ternary complex
Authors: Sarkar Bibudhendra , Wigfield Yuk
Published: December 2009

Commercially obtained pure human serum albumin (HSA) was shown to contain molecular aggregates and was significantly contaminated with Cu(II). A solution of commercial HSA was first passed through a Sephadex G-200 column to obtain pure monomeric HSA. The monomer of HSA was subsequently passed through Chelex-100 resin to free it from Cu(II). All Cu(II)-binding studies were conducted with monomeric and copper-free HSA. The first Cu(II)-binding site on HSA appears to be stronger than the second and the subsequent binding sites. Significant amounts of L-histidine and L-threonine were bound to HSA when Cu(II) was added in the form of Cu(II) – amino acid complexes. In the absence of Cu(II), free L-histidine or L-threonine do not bind to HSA at pH 7.4. It is concluded that, in the presence of either L-histidine or L-threonine, ternary complex formation is involved both at the first and the subsequent binding sites for Cu(II) on HSA. In view of this finding, it appears that the equilibrium between HSA–Cu(II) and Cu(II) – amino acid complex is mediated through a ternary complex HSA – Cu(II) – amino acid.
Bromouracil-resistant mutant of Chlamydomonas
Authors: Hipkiss Alan R.
Published: December 2009

5-Bromouracil (BU) inhibited the growth of wild-type Chlamydomonas reinhardi. Two BU-resistant mutant strains were isolated that were resistant to it, and grew readily in the presence or the absence of BU. They did not use BU or thymine in the synthesis of DNA.
Phosphoglucoisomerase activity in the atherosclerotic aorta. I
Authors: Anastassiades T. , Denstedt O. F.
Published: December 2009

Specimens of human aortic tissue taken at autopsy were selected on the basis of clinical and pathological criteria. Normal and atherosclerotic areas were excised from each specimen and the intima was separated from the media by dissection. Samples of each dissected specimen were taken for measurement of phosphoglucoisomerase (PGI) activity and analysis for the content of moisture, total nitrogen, noncollagen nitrogen, and DNA. While little difference was found in PGI activity between the normal and atherosclerotic areas when the activity was calculated on the basis of the wet or dry weight of the tissue, a significantly higher activity was revealed in the atherosclerotic intima specimens when the values were calculated on the basis of the content of nitrogen, DNA, or noncollagen nitrogen. The last two criteria reflect the total cell number and total cell mass, respectively, and when used for the calculation of PGI activity give the best agreement.
Molecular weight of erythropoietin from anemic sheep plasma and human urine
Authors: Lukowsky W. , Painter R. H.
Published: December 2009

The properties of erythropoietin from sheep plasma and human urine were compared by gel filtration in columns of Sephadex G-150 calibrated with proteins of known molecular weight. Erythropoietin activity eluted as a single component in good yield at an elution volume consistent with a molecular weight of 60 000 in each case. No activity was detected in other fractions of the eluate, indicating the homogeneity of erythropoietin from both sources.
Serum protein alterations in adjuvant-induced arthritis
Authors: Weimer Henry E. , Wood Fae D. , Pearson Carl M.
Published: December 2009

The effects of adjuvant-induced arthritis in the rat on serum protein alterations were investigated in a longitudinal study. Injection of an emulsion of the Wax D fraction of the tubercle bacillus in oil elicited pronounced elevations in the α1-globulin, α2-globulin, and seromucoid fractions, and the total serum glycoprotein within 24 h. During the acute stage of the disease, significant increases were observed in protein-bound hexose, and in the fibrinogen, seromucoid, α1-, α2-, and β-globulin fractions. A new protein, α2-AP (acute phase) globulin, appeared in the serum concomitant with decreased levels of total protein, albumin, and γ-globulin. Remission was characterized by a reversal of the above changes. Spontaneous renewal of the arthritic symptoms caused comparable but less marked serum changes similar to those observed in the various clinical phases of rheumatic disease in man. It was concluded that although the serum changes parallel to a certain extent the degree of pathologic activity, they are not specific, and reflect a common systemic response to inflammation.
O-Isopropylidene derivatives of D-allulose (D-psicose) and D-erythro-hexopyranos-2,3-diulose
Authors: Cree G. M. , Perlin A. S.
Published: December 2009

Oxidation of 1,2: 4,5-di-O-isopropylidene-β-D-fructopyranose (2) with ruthenium tetroxide affords crystalline 1,2: 4,5-di-O-isopropylidene-β-D-erythro-hexopyranos-2,3-diulose (3) in high yield. The latter, on reduction with metal hydrides or on catalytic hydrogenation over platinum, yields 1,2: 4,5-di-O-isopropylidene-β-D-allulopyranose (4) as virtually the sole product. By contrast, sodium amalgam reduction of 3 yields only the D-fructose derivative (2), although in low yield. Also, metal hydride reduction of impure 3, obtained by oxidation of 2 with dimethyl sulfoxide – acetic anhydride, yields equal amounts of both isomers (2 and 4). The stereochemistry of these reductions is complicated by uncertainty as to the conformation of 4 (and possibly of 2), owing to anomalous proton magnetic resonance spectral characteristics observed.Ketone 3, which is unstable in the presence of deuteroxide ion, is smoothly deuterated at C-4 by exchange in hot deuterium oxide – pyridine.Mono-O-isopropylidene derivatives have been prepared by partial acid hydrolysis of 2 and 4.
The photolysis of O-methylcytosine in phosphate solutions
Authors: Pitha P. M. , Butler G. C.
Published: December 2009

Ultraviolet irradiation of solutions of 27 pyrimidine derivatives in the presence and absence of inorganic orthophosphate demonstrated a "phosphate effect" in only four cases. Each of these had a methyl or methoxyl group at position 2 and an amino group at position 4 of the pyrimidine ring. Ultraviolet irradiation of solutions of 4-amino-2-methoxypyrimidine containing inorganic orthophosphate gave two major photoproducts, neither of which contained a cyanide group. One was an aliphatic compound described previously, the other apparently a pyrimidine.
Photochemical cross sections in cytidylyl-(3′-5′)-cytidine
Authors: Hariharan P. V. , Johns H. E.
Published: December 2009

Ultraviolet irradiation of cytidylyl-(3′-5′)-cytidine (CpC) results in the production of only one dimer, [Formula: see text], and for ultraviolet exposures in the range of biological interest, only the single hydrate (CpC)*. A second dimer of CpC, [Formula: see text], arises from [Formula: see text] through a dark reaction. Both these dimers deaminate in the dark to dimers of uridylyl-(3′-5′)-cytidine (UpC) and then to [Formula: see text]. The cross sections and quantum yields for the production of [Formula: see text] and (CpC)* have been determined at a number of wavelengths. In the wavelength range 240–289 mμ, the cross sections for dimer production are at least two times that for hydrate production. Approximate molar extinction coefficients have been determined for a mixture of [Formula: see text] and [Formula: see text], yielding values at ail wavelengths which are at least four times larger than for thymine dimers. The cross sections for dimer reversal of [Formula: see text] and [Formula: see text] are about the same and are larger than those of thymine dimers by at least a factor of 6.0. The quantum yield for reversal of CpC dimers is about 1.0 and independent of wavelength. These photochemical findings prove that in CpC, dimers are a much more important class of photoproduct than hydrates at low ultraviolet exposures. A similar result could be expected in polymers containing cytosine such as occur in DNA and RNA.
Aggregation of an immunoglobulin fragment by sulfhydryl oxidation
Authors: Luks Cynthia I. , Connell G. E.
Published: December 2009

An immunoglobulin of the IgG family has been isolated from the serum of a patient with multiple myeloma. The IgG was subjected to plasmin digestion and the resulting Fab fragment was isolated and characterized. Incubation of this fragment in denaturing solvents, such as aqueous 8 M urea at either pH 3.4 or pH 8.2, resulted in the formation of a dimer as the main product. In some cases more complex products were formed in addition to the dimer. Free sulfhydryl titrations and blocking experiments indicated that the transformation reaction consisted of cross-linking of two Fab fragments by oxidation of sulfhydryl groups. The original immunoglobulin proved to have two sulfhydryl groups per mole, which are unreactive except in the presence of denaturing solvents.
Characterization of glycopeptides derived from the low-density lipoprotein of hen's egg yolk
Authors: Augustyniak J. Z. , Martin W. G.
Published: December 2009

Two glycopeptides (A and B) were isolated from pronase-digested vitellenin, the protein moiety of the low-density lipoprotein of hen's egg yolk. Aspartic acid was the only N-terminal amino acid of both glycopeptides but only A contained N-acetylneuraminic acid. A contained 55% hexose (mannose), 14% hexosamine, 12% N-acetylneuraminic acid, 0.71% amide nitrogen, and its molecular weight was 2.3 × 103. The corresponding values for B were 64, 17, 0.0, 0.75, and 2.0 × 103. Chemical analyses showed that B (and probably A) occurs in vitellenin with the heteropolysaccharide group bound N-glycosidically via the β-amide group of an asparaginyl residue. The indicated structure is R∙(NH)Asp∙Thr∙Ser∙(Ala, Gly, Val)∙Ile, where R, the heteropolysaccharide group, contains 2 hexosamine and 8 hexose residues.
Effect of some pesticides on the adrenal glands in the rat
Authors: Foster T. S.
Published: December 2009

Ingestion of powdered standard laboratory ration containing DDD, DDT, or malathion at 100 and 200 p.p.m. levels for periods up to 42 days was not toxic to rats nor did it have any effect on weight gain, adrenal weights, or the production of steroids by quartered adrenals in vitro. When fed at a 200 p.p.m. level, dieldrin was extremely toxic, resulted in decreased weight gains, increased adrenal weights, and decreased production of steroids by quartered adrenals in vitro. In addition, there was an increased production of progesterone and deoxycorticosterone from pregnenolone-4-14C, in vitro, by quartered adrenals from rats ingesting a diet containing 200 p.p.m. dieldrin, and a concomitant decrease in the production of 18-hydroxydeoxycorticosterone, corticosterone, and 18-hydroxycorticosterone. This has been interpreted to indicate a partial inhibition of an enzyme, probably a steroid 11β-hydroxylase.
Studies on the chemical constitution of cell-wall lipopolysaccharides from Neisseria perflava
Authors: Adams G. A. , Kates M. , Shaw D. H. , Yaguchi M.
Published: December 2009

Lipopolysaccharides (LPS) were prepared from Neisseria perflava cells and separated into chloroform-soluble and chloroform-insoluble fractions in about equal proportions. The preparations were almost free from protein and contained only traces of peptide material. Both LPS fractions contained 3-deoxyoctulosonic acid (KDO), lipid A, glucose, rhamnose, heptose, glucosamine, galactosamine, ethanolamine, phosphate, and fatty acids. Both fractions had the same proportions of hexosamines and ethanolamine and the same fatty acid components (chiefly β-hydroxymyristic, β-faydroxylauric, octadecenoic, and palmitic acids), but differed markedly in their relative molar proportions of KDO to neutral sugars and of neutral sugars to total fatty acids. Equimolar proportions of hexosamine, ethanolamine, and phosphate in the lipid A moieties suggested that ethanolamine phosphate was linked to glucosamine, probably at the C-6 position. Fatty acids were bound in the LPS by both amide and ester linkages. Heptose units were linked linearly by 1 → 3 glycosidic bonds. About 25% of the glucose units were linked 1 → 3 in a chain; other glucose units were branched as were the rhamnose units. The proportions and arrangement of the heptose, KDO, and lipid A components suggest that the backbone part of the N. perflava lipopolysaccharide is very similar to that found in the Salmonella-Escherichia group.
Preparation and properties of the optical antipodes of β-methoxyvaline and β-hydroxyvaline
Authors: Edwards George W. , Minthorn Jr. Martin L.
Published: December 2009

DL-Methoxyvaline was resolved by the selective precipitation of the L-form as d-10-camphorsulfonate in the form of a monomethanolate. Hydrolysis of the β-methoxyvalines with hydrobromic acid gave the two optical isomers of β-hydroxyvaline of which only the L-form is a competitive antagonist of valine for Lactobacillus arabinosus 17-5.
Mechanism of inhibition of ribonuclease by bentonite
Authors: Jacoli G. G.
Published: December 2009

A study of the mode of inhibition of RNase by bentonite showed that the inactivation of the enzyme could not be attributed solely to an ion-exchange effect as previously postulated. Vermiculite, which is a clay with higher cation capacity than bentonite, showed very little inactivation of RNase. The spatial arrangement of the clay matrix must also play an important role in accommodating the enzyme molecule. Inactivation of the enzyme by photooxidation did not alter the retention of RNase by bentonite.
Degradation of the carbon skeleton of glutamic acid
Authors: Simon Stuart H. , O'Neill John J.
Published: December 2009

Glutamic acid labeled with 14C was converted to succinic semialdehyde by the action of Chloramine-T, the aldehyde was converted to the hydrazone, and the hydrazone was converted to butyric acid by thermal decomposition. Maximum yield of butyric acid was obtained if the temperature of the liquid phase was not lower than 195 °C during the 4 h of refluxing to decompose the hydrazone.
Effect of wounding on the synthesis of phenols, phenol oxidase, and peroxidase in the tuber tissue of Jerusalem artichoke
Authors: Bastin Marcel
Published: December 2009

Slices of tubers of Jerusalem artichoke were cultured at 28 °C in complete darkness, and the production of phenolic acids, phenol oxidase, and peroxidase was studied in relation to subsequent cutting of the tissue. Wounding increased the production of both phenolic acids and enzymes. Purification of the peroxidase by DEAE-cellulose chromatography showed that not all of its components were synthesized in the injured slices. Cycloheximide and chloramphenicol were added to cultures to investigate a requirement for the de novo synthesis of protein in relation to production of the compounds. Cycloheximide at a concentration of 5 μg/ml strongly inhibited the production of both phenolic acids and the enzymes, but chloramphenicol decreased the production of only phenol oxidase.
Effects of modifiers on the kinetics of two-substrate enzyme reactions
Authors: Henderson J. Frank
Published: December 2009

Steady state rate equations have been derived for ordered bi bi and ping pong bi bi reactions in which there are (a) one or two nonsubstrate modifiers, (b) two different binding sites for a single nonsubstrate modifier, (c) one or two substrates acting as modifiers, and (d) both nonsubstrate modifiers and substrates acting as modifiers. The deviation of these equations from the Michaelis–Menten equation is shown and methods are suggested by which many of these mechanisms can be distinguished experimentally.
Evidence for the absence of selenocystine and selenomethionine in the serum proteins of chicks administered selenite
Authors: Jenkins K. J.
Published: December 2009

The nature of 75Se-labeled material in the serum proteins of chicks intubated with 75SeO32− was investigated. Serum was exhaustively dialyzed against 0.9% NaCl and then subjected to nonproteolytic treatments for the release of 75Se activity. Reduction of serum proteins obtained 4 h after 75Se administration with 0.25 M 2-mercaptoethanol, 0.10 ML-cysteine, 0.10 M reduced glutathione, or 0.02 M dithiothreitol in the presence of 8 M urea released 76–89% of the radioactivity within 2 h. Sulfitolysis and dialysis against dilute NaOH, pH 11.5, for 2 days liberated 83% and 90%, respectively. At later times after 75SeO32− administration, progressively less 75Se activity was removed by reduction or sulfitolysis, whereas the alkali treatment remained equally effective. On paper chromatography, the alkali-released material separated into two radioactive areas, one attributable to 75SeO32− and the other tentatively identified as colloidal, elemental selenium. No radioactive selenocystine, selenomethionine, or other ninhydrin-positive material was released. None of the treatments employed to discharge the element caused the release of 75SeO32− from 75Se-labeled selenomethionine or selenocystine standards. The evidence suggests that the bulk of 75Se existed in the serum proteins covalently bound between the sulfurs of half-cystine residues.
Agents affecting lipid metabolism. XXXVI. Effect of N-cyclohexyl linoleamide on hepatic cholesterogenesis in vitro
Authors: Dvornik D.
Published: December 2009

N-Cyclohexyl linoleamide, reported to be antihypercholesterolemic in rabbits, was examined for its effect on hepatic cholesterogenesis in vitro. At a final concentration of 1 × 10−3 M the compound had no effect on the incorporation into cholesterol of 3H-acetate and 2-14C-mevalonate incubated simultaneously with normal rat liver homogenates.
Studies of the uptake of macromolecules by cells. I. Uptake of proteins by cells of the Ehrlich–Lettré ascites carcinoma
Authors: Choi Y. C. , Kay E. R. M.
Published: December 2009

The uptake of protein by cells of the Ehrlich–Lettré ascites carcinoma was characterized kinetically by using hemoglobin as a model protein. An attempt was made to show that the process is not an artefact due to nonspecific adsorption of protein to the cell membrane. The kinetics of the uptake process suggested that an interaction exists between the exogenous protein and specific binding sites on the membrane. Acetylation of hemoglobin enhanced the rate of uptake of this protein. Treatment of cells with neuraminidase, phospholipase A, and Pronase resulted in an inhibition of protein uptake. The experimental evidence for the uptake of hemoglobin was supported by evidence that L-serine-U-14C-labelled hemoglobin is transported into the cytoplasm and utilized subsequently, resulting in labelling of the nucleic acid nucleotides.
Amino acid, sugar, and organic acid content during germination of Gateway barley and its chlorophyll mutant
Authors: Sane P. V. , Zalik Saul
Published: December 2009

Amino acids and total soluble sugars in the embryo and endosperm of etiolated seedlings of Gateway barley and its mutant were compared over a 10-day period. The endosperm of the mutant had a lower reserve of protein but the levels of protein and free glycine, which is the nitrogenous precursor of chlorophyll, were similar in the embryos of both lines. Thus the low reserve of nitrogen in the mutant seed was not responsible for its virescent character. Based upon the changes in the amounts of endogenous amino acids it appeared that the free amino acids were direct precursors of protein. The content of total soluble sugars was similar in both lines. Shoots of light-grown seedlings of the mutant accumulated considerably more malate than those of the normal line. Although there was special interest in determining the amount of succinate at different stages of seedling development, none was detectable until the 10th day.
Metabolism of high molecular weight, polydisperse, rapidly labeled nuclear RNA in rat liver
Authors: Brossard Maurice , Nicole Louis
Published: December 2009

Studies of the metabolism of rat liver RNA showed the existence of two species of rapidly labeled nuclear RNA: a 45 S preribosomal type of nucleolar origin, and a 6–50 S polydisperse RNA of chromosomal origin. The kinetics of labeling with orotic acid-14C and the nature of the latter RNA have been investigated. The following findings are reported, (1) This RNA is composed of at least four main classes of RNA having sedimentation coefficients of approximately 45, 35, 24, and 18 S. (2) Except for the 18 S class which seems to be an end product, the three other classes have a rapid turnover and do not appear to leave the nucleus. (3) Base analysis after 32P incorporation indicates that these four classes of RNA have a similar base composition with a G+C/A + U ratio in the range of 0.98–1.07, which resembles DNA more closely than ribosomal RNA. (4) The 6–50 S polydisperse RNA has a different metabolism than that of the 45 S preribosomal type and there is no precursor-to-product relationship between these two species of RNA.
Isolation and characterization of antigenic components of rat glomerular basement membrane
Authors: Huang F. , Kalant N.
Published: December 2009

(1) A method was developed to separate normal rat glomerular basement membrane (GBM) into six components by collagenase digestion, urea extraction, and gel filtration.(2) Treatment of rat GBM with collagenase did not alter nephrotoxic antigenicity of the membrane. Further proteolytic digestion with pronase resulted in loss of ability to elicit nephrotoxic antibody. Rat GBM prepared by mild alkali treatment still retained nephrotoxic antigenicity.(3) Antibodies against isolated components, except two which were retained on Sephadex G-75, localized to GBM and induced proteinuria in rats. One of the components retained on Sephadex G-75 produced localizing, non-nephrotoxic antibodies, while the other produced no localizing antibodies. Multiple antigens and common antigenic determinants among membrane components were demonstrated by gel double diffusion.(4) A specific nephrotoxigenic antigen from rat GBM was characterized as a macromolecular glycoprotein containing 10.7% carbohydrate in the form of galactose, mannose, sialic acid, glucosamine, and galactosamine. On analytical ultracentrifugation in Tris buffer, it gave two peaks with sedimentation constants of 5.93 and 3.49 S, while in 8 M urea it appeared as a single symmetrical peak with lower sedimentation constant (1.33 S) suggesting the presence of aggregate forms of the glycoprotein.(5) Dog GBM and collagenase-solubilized components elicited antibodies which localized to rat GBM but failed to produce proteinuria. Antibody to tendon collagen also localized to rat GBM but had no nephrotoxic effect on normal rats. Antibody to collagen fragments obtained from collagenase digestion failed to localize on rat GBM but still cross-reacted with tendon collagen in gel diffusion.
The analysis of dead-end inhibition patterns for multisubstrate systems
Authors: Hurst R. O.
Published: December 2009

The additive effect of a dead-end inhibitor combining in linear fashion with more than one of the enzyme species in a reaction mechanism is demonstrated. An equation for the calculation of the inhibitor constants that are required for the multicombinations of inhibitor from those obtained for the inhibitor combining with only one enzyme form is provided. A method of tabulation of the inhibitor constants with respect to the coefficients of the denominator terms of the full rate-equation for the uninhibited reaction is given, that facilitates the analysis of the inhibition patterns for the several inhibitor complexes that may be formed. The usefulness of the method for calculating the rate constants for a 'Ping Pong Bi Bi' mechanism is illustrated.
The enzymic deacylation of esterified mono- and di-saccharides. I. The isolation and purification of an esterase from wheat germ lipase
Authors: Fink A. L. , Hay G. W.
Published: December 2009

Whereas wheat germ lipase was known to contain acid phosphatase (EC 3.1.3.2), esterase (EC 3.1.1.1), and lipase (EC 3.1.1.3) activity, a cursory examination of some commercial enzymes has demonstrated also the presence of phosphodiesterase (EC 3.1.4.1), α- and β-glucosidase (EC 3.2.1.20 and EC 3.2.1.21), α- and β-galactosidase (EC 3.2.1.22 and EC 3.2.1.23), α-mannosidase (EC 3.2.1.24), and β-xylosidase (EC 3.2.1.37) activities. Disc electrophoresis revealed a minimum of 12 electrophoretically distinct protein fractions. Different sources and different batches of enzyme had similar disc electrophoretic behavior and activities. Fractionation of the crude preparation on carboxymethylcellulose or Sephadex, and electrophoresis on Sephadex, failed to separate α-glucosidase and esterase activities. The inhibition of α- and β-glucosidase could be effected by D-glucono-1,5-lactone, but not by metal salts or Tris.Preparative polyacrylamide-gel electrophoresis of wheat germ lipase gave a large number of active zones including several esterases, acid phosphatase, and α- and β-glucosidase fractions. Evidence was established for the nonidentity of two neighboring esterase zones. One was found to be free of α- and β-glucosidase activity. Sulfhydryl reagents inhibited the esterases, whereas acetone activated some and inactivated others. The esterases were most stable at neutral pH and were extensively inactivated on lyophilization, dialysis, and desalting with molecular-sieving reagents. Some properties of the purified esterase were examined.
Hemoglobin Etobicoke: α84(F5) serine replaced by arginine
Authors: Crookston J. H. , Farquharson Helen A. , Beale D. , Lehmann H.
Published: December 2009

In a Canadian family of northern Irish origin, a new hemoglobin variant, hemoglobin Etobicoke, was observed. It differs from hemoglobin A by having a residue of arginine in place of serine in position 84 of the α-chain (helical notation F5). This hemoglobin is slightly less stable than hemoglobin A, but it does not cause an inclusion body anemia.
Failure to detect p-methoxyphenylethylamine derivatives in human urine
Authors: Jones R. L. , Bory P. , Brown W. T. , McGeer P. L.
Published: December 2009

No positive evidence could be found for the appearance in urine from either normal people or schizophrenics of 3,4-dimethoxyphenylethylamine, p-methoxyphenylethylamine, 3,4-dimethoxyphenylacetic acid, or p-methoxyphenylacetic acid. It was confirmed that these amines when ingested are excreted largely as the acids so that failure to find the acids in urine in detectable amounts (10 μg/24 h) indicates that the amines, if present at all, would be far below the limits detectable by the methods used (5 μg/24 h). The discrepancy between this and previous reports may depend on the particular urine specimens studied but is more likely a reflection of resolution difficulties in gas, paper, and thin-layer chromatography. Ninety percent of the radioactivity of administered p-tyramine-2-14C was accounted for in the urine with no evidence of any p-methoxylated derivative. Various common foodstuffs do not contain detectable amounts of these p-methoxylated amines or acids.
Depolymerization of polyadenylic acid by subcellular fractions of rat brain and liver
Authors: Murthy M. R. V. , Bharucha A. D. , Raynaud-Jammet C.
Published: December 2009

Rat brain and liver homogenates depolymerized polyadenylic acid when added to a reaction mixture containing this polynucleotide. The activity in the homogenate declined progressively with the age of the tissues. This was reflected in a parallel reduction in the activity of the soluble fraction. In brain, the activity in the nuclear fraction also declined in the adult to half the level of the newborn. In contrast, liver nuclei had approximately the same activity at all stages of growth.With advancement in age, an increasingly greater proportion of the total activity of the tissues was contained in the nuclear fraction, while at the same time the proportion of activity in the soluble fraction decreased. The proportion of activity contained in the mitochondrial–microsomal fraction also increased with growth in brain, with the maximum increment in activity occurring after 8 weeks of age. In liver, there was actually a decrease of activity in this fraction during the same period. At all ages, the mitochondrial–microsomal fraction of brain contained a higher proportion of activity and the nuclear fraction of brain contained a lower proportion of activity compared to corresponding fractions of liver. The presence of polyadenylic acid degrading activity in these fractions and its relative increase with age may indicate a changing emphasis in the pattern of RNA metabolism during growth; for example, a higher rate of RNA synthesis in the young and a higher rate of RNA turnover in the adult.When the soluble fraction of rat brain was dialyzed, the polyadenylic acid degrading activity of this fraction was stimulated by the addition of inorganic orthophosphate. Brain and liver homogenates also mediated an ADP – inorganic phosphate exchange reaction which was highest in the newborn and decreased rapidly with age. These observations indicate that at least a part of the polyadenylic acid degrading activity in brain and liver extracts may be due to phosphorolytic action.
Hyperphenylalaninemia: effect on the developing rat brain
Authors: Clarke J. T. R. , Lowden J. A.
Published: December 2009

Hyperphenylalaninemia was produced by injecting L-phenylalanine into suckling rats on two occasions within 2 h, daily from 2 to 20 days. Serum phenylalanine levels over 20 mg/100 ml were maintained for more than 12 h. The brains of the experimental animals weighed less and contained less myelin lipid than those of controls.
Some features of the optical rotatory dispersion spectrum of the α-lytic protease of Sorangium sp.
Authors: Paterson G. M. , Whitaker D. R.
Published: December 2009

A study of the kinetic properties of the α-lytic protease of Sorangium sp. indicated that substrate-binding by the enzyme was not pH dependent. In agreement with this indication of a pH-insensitive conformation, the optical rotation of the enzyme between pH 5 and 10.5 is not pH dependent. The optical rotatory dispersion spectrum above 220 mμ shows a main Cotton effect with a trough at 230 mμ and small but well-marked Cotton effects between 260 and 300 mμ. The reduced, mean residue rotation at the trough of the main Cotton effect was estimated to be −1650 ± 80° cm2/dmole; the Moffitt–Yang parameter b0 for rotations above 325 mμ is approximately zero. These values suggest that the enzyme has virtually no α-helices.
Amino acids in blood plasma and tissues of rats following glucose force-feeding
Authors: Knipfel J. E. , Botting H. G. , Noel F. J. , McLaughlan J. M.
Published: December 2009

Changes in plasma amino acid (PAA) concentrations effected by force-feeding glucose to rats were studied in two experiments. Attempts were made to relate PAA concentration changes to amino acid requirements, previous diet, time after feeding glucose, and composition of several body proteins. Distribution of 14C-lysine between blood and tissues was examined in an additional rat experiment. Previous diet did not affect the relative quantities of amino acids removed from plasma (PAA removal pattern) after glucose force-feeding. Minimal PAA concentrations occurred by 40 min after glucose administration. The PAA removal pattern was not distinctly related to either amino acid requirements or to any particular body protein composition. Results of administering 14C-lysine simultaneously with glucose indicated that decreased plasma 14C-lysine levels were caused by increased tissue uptake of 14C, likely mediated by insulin. Muscle acted as the major recipient of 14C from plasma, with liver a lesser and more dynamic reservoir of 14C accumulation. Work is continuing to further clarify the significance of the PAA removal pattern, caused by the force-feeding of glucose.
Amino acid composition of gluten fractions
Authors: Yang Haung-Ju , McCalla A. G.
Published: December 2009

Gluten dispersions in 10% sodium salicylate were fractionated by precipitation with increasing concentrations of magnesium sulfate. Dialysis of the dispersion against the dispersing agent to which sodium bisulfite had been added served merely to sharpen the separation of the fractions. Dialysis against the dispersing agent to which sodium sulfite had been added resulted in failure to recover much of the less soluble portion of the gluten by precipitation. It is suggested that the sulfite ruptured disulfide bonds of the less soluble fractions of gluten.The amino acid composition of successive fractions varied regularly, with the less soluble fractions containing less glutamic acid and proline and more arginine, lysine, aspartic acid, threonine, glycine, alanine, and tryptophan than did the more soluble fractions. This relationship among fractions was not altered by the exposure of gluten to reducing agents.Precipitates produced during hydrolysis of the gluten fractions by papain also varied regularly in amino acid composition but the proportions of individual amino acids were entirely different from those for the total protein in the fraction.Gluten must be considered as a complex combination of protein components but the number of components involved cannot yet be determined.