bluuebunny/crossref_metadata_2025 huggingface dataset:
STUDIES ON THE METABOLISM OF INSULIN BY PANCREAS IN VITRO: I. DEGRADATION OF EXOGENOUS INSULIN BY CALF PANCREAS SLICES
Authors: Schucher Reuben
Published: December 2009

A study was made of the nature and significance of the production by calf pancreas slices of TCA-soluble radioactivity from insulin-I131, as a measure of insulin degradation. Insulin degradation increased with time of incubation, and with tissue and insulin (substrate) concentration. The degrading system showed pH and temperature optima and was heat labile. Inhibition by poisons for —SH-containing enzymes was shown; inhibitors of hepatic "insulinase" also inhibited pancreatic "insulinase". Soybean trypsin inhibitor and cinnamic acid, which prevented the breakdown of insulin by crystalline trypsin, were without effect upon pancreatic "insulinase". Several degradation products were found. The results all support the conclusion that calf pancreas slices contain an active insulin-degrading system which apparently acts by catalyzing proteolytic breakdown of insulin into TCA-soluble fragments. This enzyme system ("insulinase") is similar to, but not identical with, liver "insulinase".
INDUCTION OF DDT-METABOLIZING ENZYMES IN MICROSOMES OF RAT LIVER AFTER ADMINISTRATION OF DDT
Authors: Morello Antonio
Published: December 2009

DDT is metabolized by rat liver microsomes to a phenolic compound and to a reduced derivative similar to DDD. When rats were injected intraperitoneally with DDT, the microsomal DDT-metabolizing activity was greatly increased. This effect was blocked by the administration of puromycin. DDT administration also increases the content of liver microsomal protein. The results show that the insecticide probably increases the DDT-metabolizing activity of mammalian liver by inducing enzyme synthesis.
LIPIDS OF THE FIN WHALE (BALAENOPTERA PHYSALUS) FROM NORTH ATLANTIC WATERS: II. FATTY ACID COMPOSITION OF THE LIVER LIPIDS AND GAS–LIQUID CHROMATOGRAPHIC EVIDENCE FOR THE OCCURRENCE OF 5,8,11,14-NONADECATETRAENOIC ACID
Authors: Ackman R. G. , Eaton C. A. , Jangaard P. M.
Published: December 2009

The fatty acid composition of the liver lipids of the fin whale (Balaenoptera physalus) closely resembles that of terrestrial mammals. Gas–liquid chromatographic evidence indicates that 5,8,11,14-nonadecatetraenoic acid is present, and the origin of this acid in association with 5,8,11,14-eicosatetraenoic acid is discussed.
THE MODE OF ACTION OF PANCREATIC LIPASE ON MILK FAT GLYCERIDES
Authors: Boudreau A. , deMan J. M.
Published: December 2009

Hydrolysis of tricaprylin by pancreatic lipase resulted in a stepwise hydrolysis, triglyceride to diglyceride to monoglyceride, as has been obtained with long-chain triglycerides. However, hydrolysis rates were much faster and considerable amounts of free glycerol were formed. Hydrolysis of an equimolar mixture of tricaprylin and triolein indicated that some of the short-chain fatty acid was released from the 2-position before all of the oleic acid was released from the 1-position. Hydrolysis of genuine and randomized milk fat resulted in preferential hydrolysis of glycerides containing short-chain fatty acids. This phenomenon was not dependent on a specific distribution of these acids, since it also occurred with the randomized fat. It was concluded that part of the short-chain fatty acids of milk fat is located in the 2-position. The distribution of caprylic and capric acids between the 1- and 2-positions is approximately at random. Lauric, myristic, and palmitic acids are predominantly located in the 2-position, and stearic and oleic acids in the 1-position, of milk fat glycerides.
THE DETERMINATION OF TERMINAL PROTEIN-BOUND FUCOSE
Authors: Gyorky G. , Houck J. C.
Published: December 2009

The spectrophotometric determination of protein-bound fucose is badly compromised by spurious chromagens developed from protein degradation products. To minimize the contribution of these spurious products to the color yield of fucose, the glycoprotein was partially hydrolyzed in dilute acid, thus releasing the terminal carbohydrate from the protein moieties, and the residual protein was removed with trichloroacetic acid. That the fucose content of this supernatant was real was confirmed by paper chromatography and spectral studies.The spurious chromagens were shown to result from the interaction of protein degradation products and galactose.
LYTIC ENZYMES OF SORANGIUM SP.: ACTION OF THE α- AND β-LYTIC PROTEASES ON TWO BACTERIAL MUCOPEPTIDES
Authors: Tsai C. S. , Whitaker D. R. , Jurášek L. , Gillespie D. C.
Published: December 2009

The α- and β-lytic proteases hydrolyzed mucopeptides from the walls of Arthrohacter globiformis and Micrococcus lysodeikticus cells. The Arthrobacter mucopeptide was the more readily degraded substrate; the β-enzyme was the more active enzyme. Hydrolysates of Micrococcus mucopeptide showed the simpler electrophoretic pattern of ninhydrin-positive components.Analyses for C-terminal amino acids (after hydrazinolysis) and for dinitrophenyl amino acids (after dinitrophenylation) showed that the hydrolyses of Micrococcus mucopeptide were accompanied by increases in (a) C-terminal glycine and, to a lesser extent, in (b) C-terminal alanine, and by increases in (c) free ε-amino groups of lysine residues and in (d) N-terminal alanine residues. A brief hydrolysis with the β-enzyme gave slightly to moderately greater increases in a, b, and c, and a much greater increase in d, than a prolonged hydrolysis with the α-enzyme at a higher enzyme concentration.The soluble peptides hydrolyzed from Micrococcus mucopeptide by each enzyme were isolated by ion-exchange chromatography. Their composition, and that of the main hydrolysis product of the α-enzyme (an insoluble gel), was compared with that of untreated mucopeptide. The amino acids of the four products remained in approximately the same molar ratio relative to glutamic acid: Ala2.2, Gly1.0, Lys1.0, Glu1.0. N-Acetyl muramic acid and N-acetyl glucosamine were estimated by gas–liquid chromatography. Relative to glutamic acid, the molar ratio of each amino sugar was about 3.0 in the mucopeptide, 5.0 in the gel, and 0.6 in the soluble peptides. Half the glycyl residues of the mucopeptide and virtually all the glycyl residues of the other three products were analyzed as C-terminal glycine. Subtractive Edman analyses showed little change in the Ala:Glu ratio of the mucopeptide and of the gel but a substantial decrease in the ratios for the soluble peptides. The titratable acidity of the mucopeptide and the gel was consistent with these analyses.It is concluded that cross-linkages from the C-terminus of the peptide chains of the mucopeptide are hydrolyzed by both enzymes and that the linkage between N-acetyl muramic acid and the alanyl residue at the N-terminus of the peptide chains is hydrolyzed rapidly by the β-enzyme and slowly by the α-enzyme.
METABOLISM OF VANILLIN AND RELATED SUBSTANCES IN THE RAT
Authors: Wong Kim Ping , Sourkes T. L.
Published: December 2009

Intraperitoneal administration of vanillin (4-hydroxy-3-methoxybenzaldehyde) to rats gave rise to a number of urinary products, chief among which was vanillic acid, in both free and conjugated forms. Other metabolites were conjugated vanillin, conjugated vanillyl alcohol, and catechol (pyrocatechol). Catechol continued to be formed even after treatment of the animals with neomycin and streptomycin for 72 hours before the vanillin was administered. Besides vanillin, the following exogenous compounds were shown to be sources of urinary catechol: protocatechuic aldehyde, protocatechuic acid, vanillic acid, and guaiacol. Noradrenalone, adrenalone, and isoprenalone were not precursors. Treatment of rats with disulfiram, an inhibitor of aldehyde oxidase, before the administration of vanillin resulted in a decrease in the proportion of vanillic acid formed and an increase in that of vanillyl alcohol. Disulfiram also interfered with the formation of catechol from guaiacol.
LINGCOD MUSCLE GUANINE DEAMINASE
Authors: Roy Joan E.
Published: December 2009

The enzyme guanine deaminase was found in lingcod muscle and a study of its properties carried out. In the crude state, two pH optima were found, one of which was lost on purification. Of several guanine analogues tested, only 8-azaguanine was deaminated by the enzyme. A number of compounds were tested as inhibitors. No cofactors were required. A purification of over 200-fold is described which involves three steps. The Km was determined as 3.3 × 10−5 M.
STEROLS IN IRISH MOSS (CHONDRUS CRISPUS)
Authors: Saito Akira , Idler D. R.
Published: December 2009

Sterol was isolated from Irish moss (Chondrus crispus) harvested in Nova Scotia. The principal sterol was identified as cholesterol by thin-layer chromatography, gas–liquid chromatography, infrared spectra, and chemical constants of the sterol and its derivatives. The total and free sterol content of the dry seaweed were 0.012% and 0.011% respectively. The crude sterol contained 1.75% of a 5,7-dienol.
IN VITRO SCREEN OF INHIBITORS OF RAT BRAIN TYROSINE HYDROXYLASE
Authors: McGeer E. G. , McGeer P. L.
Published: December 2009

Over 600 compounds were tested at 10−4 M concentration as inhibitors of tyrosine hydroxylase activity in crude rat-brain homogenate. Most of the compounds had little or no inhibitory effect and those with strong inhibitory properties were, except for a very few oxidizing and complexing agents, all close structural analogues of tyrosine or of its catechol metabolites. Data obtained in this screen are generally in accord with previous data reported in the literature. For high inhibitory activity in the tyrosine series, side-chain substitution is critical. N-Substitution is particularly undesirable. For high inhibitory activity in the catechol series, the ring hydroxy groups should be 3,4 in relation to a C—C—N side chain. Further ring substitution is undesirable, but some side-chain substitution is permissible.
COMPLETE HYDROLYSIS OF STEROID CONJUGATES AND QUANTITATIVE EXTRACTION OF FREE STEROIDS FROM URINE
Authors: Vandenheuvel F. A.
Published: December 2009

A simple procedure for the serial hydrolysis and extraction of 5-ml urine samples is described. The samples are incubated at pH 4.45 for 24 hours at 87 °C with high concentrations of β-glucuronidase and sulfatases from Helix pomatia. The incubated samples are freeze-dried and the residual solids are repeatedly extracted with a total of 15 ml of chloroform–methanol (1:2, v/v). The overall efficiency is over 99%. A method for the systematic estimation of urinary steroids based on the combined thin-layer and gas–liquid chromatographic analysis of total extracts is outlined.
HETEROGENEITY OF INSULIN: II. CHROMATOGRAPHY OF INSULIN ON CARBOXYMETHYL CELLULOSE IN UREA CONTAINING BUFFERS
Authors: Dillon W. W. , Romans R. G.
Published: December 2009

Chromatography of insulin, on carboxymethyl (CM) cellulose columns in urea-containing buffers, revealed the presence of at least five components, one major and four minor, in commercial insulin. This fractionation is related to other chromatographic fractionations of insulin and the nature of the minor components is discussed.Insulin which had been incubated in HCl was chromatographed. The behavior of the incubated products on the column showed that two or more amide groups were hydrolyzed simultaneously but at different rates. Because of the anomalous behavior of one of the components, it is postulated that a group other than the amides is also transformed during acid incubation. This component is present in commercial insulin samples.The electrophoretic separation of insulin in urea–starch gels was shown to be due to charge differences on the molecules rather than size differences. Correlation of the components separated on the CM-cellulose column with those separated in the urea–starch gel electrophoresis showed that much smaller charge differences on the molecules are distinguished on the CM-cellulose column than in the gel.
PHOSPHONOLIPIDS: VIII. SYNTHESIS OF PHOSPHONIC ACID ANALOGUES OF DIETHERL-α-LECITHINS
Authors: Baer Erich , Rao K. V. Jagannadha
Published: December 2009

A method is described that permits the synthesis of the racemic as well as both enantiomeric forms of phosphonic acid analogues of saturated or unsaturated diether α-lecithins.The phosphonic acid analogues of diether α-lecithins are obtained by phosphonylating saturated or unsaturated D-, L-, or DL-α,β-di-O-alkyl glycerol ethers with 2-bromoethylphosphonic acid monochloride in the presence of triethylamine at 0–5°, and treating the resulting di-O-alkyi α-glyceryl-(2-bromoethyl)phosphonates with trimethylamine in dimethylformamide at 50–55°.
KINETICS FOR THE INHIBITION OF CARBOXYLESTERASE BY MALAOXON
Authors: Main A. R. , Dauterman W. C.
Published: December 2009

Malaoxon and carboxylesterase undergo two separate but simultaneous reactions when mixed in solution. One results in the irreversible inhibition of carboxylesterase. In the other, malaoxon acts as a substrate and is hydrolyzed.This work is concerned primarily with the inhibition reaction, although direct evidence of the substrate reaction is also given. It seemed possible that inhibition could occur by two mutually exclusive routes. Equations were derived for each of the two routes, and both equations gave identical and unambiguous expressions for ki, the bimolecular velocity constant of the inhibition reaction. A procedure for determining the kivalues of malaoxon and of four carboalkoxy homologues of malaoxon in reaction with partially purified rat-liver carboxylesterase is described. Evidence is given which suggested that the substrate reaction was controlled by the acylation step. This in turn suggested that useful estimates of the binding (Ka) and phosphorylation rate constants (k2p) could be made. Values for kiand tentative values for k2pand Kaare given.
ELECTROPHORESIS OF ACIDIC MUCOPOLYSACCHARIDES IN AGAROSE GEL
Authors: Horner Alan A.
Published: December 2009

A method of gel electrophoresis which separates polydisperse acidic mucopolysaccharides (AMPS) solely on the basis of differences in charge density is described. The standard procedure is to use a 0.6% agarose gel at pH 3.0 in the E-C 470 apparatus. The method shows that AMPS with the same basic polysaccharide chain structure, extracted from different tissues, may differ in electrophoretic mobility. It resolves heparin from pig intestinal mucosa into two major components.
THE INCORPORATION OF75Se-SELENITE INTO DYSTROPHOGENIC PASTURE GRASS: THE CHEMICAL NATURE OF THE SELENO COMPOUNDS FORMED AND THEIR AVAILABILITY TO YOUNG OVINE
Authors: Jenkins K. J. , Hidiroglou M.
Published: December 2009

An investigation was conducted on the nature of selenium compounds formed in brome grass obtained from a muscular dystrophy prevalent area and on the utilization of isolated fractions of the leaf seleno compounds in preruminating lambs. One week following application of75SeO32−to the leaf surfaces, 42% and 17% of the75Se activity was found to be present as selenocystine and selenomethionine, respectively, the majority of which was protein-bound. Approximately 11% of the applied selenium remained as75SeO32−. Five percent of75Se activity was attributable to three ninhydrin-negative materials of unknown composition isolated by 80% ethanol and water extractions. A trace of selenium was present bound to the leaf phospholipids. Data obtained from feeding various leaf preparations to lambs indicated that the water-soluble selenium compounds (chiefly selenite) and the seleno-amino acids contained in the ethanol and proteolytic enzyme extracts were effectively absorbed and retained. The similarity in75Se retention values for the latter extracts suggested that the uncharacterized materials in the ethanol fraction and the seleno-amino acids (enzyme digest) had comparable availabilities. The lipid-bound75Se was relatively poorly absorbed and retained. Regardless of the form of selenium ingested, the data indicated a similar distribution of the element between the tissues studied and a high proportion of activity associated with the tissue proteins.
PLASMA GLYCEROL ISOLATION AND ASSAY
Authors: Freitas A. S. W. de
Published: December 2009

A paper chromatographic procedure is described for the quantitative isolation of glycerol and glucose from a single 100-μl sample of rat plasma applied directly to Whatman No. 1 paper. Glycerol is separated from interfering paper breakdown products by rechromatography of the paper eluate on silicic acid coated plates. The concentration of glycerol in the silicic acid eluate is estimated by fluorometric assay of formaldehyde released by periodate oxidation. Glucose concentration in the appropriate paper eluate is measured spectrophotometrically after development of the arsenomolybdate chromophore.
CONJUGATED FATTY ACIDS IN SOME CUCURBITACEAE SEED OILS
Authors: Chisholm Mary J. , Hopkins C. Y.
Published: December 2009

Punicic acid was identified as a component of the seed oils of Cyclanthera explodens (26%) and Cayaponia africana (38%). α-Eleostearic acid was identified in Momordica dioica (55%) and its occurrence in Telfairia occidentalis (7 and 12%) was confirmed. Evidence of conjugated acids was noted in Fevillea peruviana and Bryonia alba. The oils of four other species of Cucurbitaceae had no conjugated acids. The distribution pattern of fatty acids in this family is discussed.
CHARACTERIZATION OF THE ESTERASES FROM ELECTRIC TISSUE OF ELECTROPHORUS BY STARCH-GEL ELECTROPHORESIS
Authors: Ecobichon D. J. , Israel Y.
Published: December 2009

The water-soluble esterases of a microsome-free supernatant of the electric tissue of Electrophorus electricus were separated by vertical-zone electrophoresis in starch gel. Specific and nonspecific substrates and inhibitors were used in conjunction with histochemical techniques to identify the enzymes. Acetylcholinesterase was present in the form of four bands of activity, the electrophoretic mobility of which was suggestive of aggregated forms of the enzyme. Pseudocholinesterase was detected as two weak bands of activity. A third esterase was identified as a nonspecific carboxylesterase and shown to be a sialoprotein.
REGULATION OF THE INITIATION OF HEMOGLOBIN SYNTHESIS IN THE BLOOD ISLAND CELLS OF CHICK EMBRYOS: V. QUALITATIVE STUDIES OF THE EFFECTS OF PROFLAVINE
Authors: Wainwright S. D. , Wainwright Lillian K.
Published: December 2009

Most blastodiscs explanted before the 1-somite stage of development onto medium containing 20 μg of proflavine/ml failed to form any detectable hemoglobin, whereas the majority explanted at later stages formed hemoglobin visible to the naked eye. Formation of hemoglobin by 2-somite blastodiscs was suppressed by proflavine at 50 μg/ml, but 6-somite blastodiscs formed visible quantities of hemoglobin. Incorporation of leucine into protein was inhibited by proflavine, and almost the same amount of inhibition was produced at both concentrations of inhibitor for all developmental stages examined.Net incorporation of uridine into acid-precipitable material was moderately inhibited by 20 μg of proflavine/ml, and almost totally suppressed by 50 μg of proflavine/ml. Only polynucleotides of low molecular weight accumulated in blastodiscs treated with either concentration of proflavine, but preformed stable RNA's were not degraded in the presence of inhibitor. Proflavine appeared to inhibit synthesis of, or cause degradation of, new RNA of high molecular weight at both concentrations. Accumulation of RNA of low molecular weight continued at a low proflavine concentration, but little additional RNA accumulated at a high proflavine concentration.
ANTIBODIES TO SEROTONIN
Authors: Ranadive N. S. , Sehon A. H.
Published: December 2009

Antibodies specific to 5-hydroxytryptamine (5HT) were produced in rabbits by immunization with 5HT–protein conjugates, which had been synthesized by coupling about 30 residues of 5HT per molecule of bovine serum albumin using the Mannich formaldehyde reaction. These antibodies had the capacity of combining in vitro and in vivo with 5HT and of inhibiting the cutaneous reactions in mice evoked by the intradermal injections of 5HT.
PHOSPHONOLIPIDS: XII. Synthesis of Phosphonolipid Metobolites.L-α-Glyceryl-(2-aminoethyl) phosphonate
Authors: Baer Erich , Sarma G. Raghupati
Published: December 2009

The synthesis of L-α-glyceryl-(2-phthalimidoethyl)phosphonic acid and of L-α-glyceryl-(2-aminoethyl)phosphonate, the latter a phosphonic acid analogue of L-α-glycerylphosphorylethanolamine and a possible intermediate in phosphonolipid metabolism, is described. The compounds were obtained by condensing D-acetone glycerol with (2-phthalimidoethyl)metaphosphonate in boiling benzene, and freeing the condensation product, viz. acetone L-α-glyceryl-(2-phthalimidoethyl)phosphonic acid, of its acetone group to obtain L-α-glyceryl-(2-phthalimidoethyl)phosphonic acid, or of its phthaloyl and acetone groups to give L-α-glyceryl-(2-aminoethyl)phosphonate.A procedure for the preparation of (2-phthalimidoethyl)metaphosphonate is reported.
BIOSYNTHESIS OF CHLORAMPHENICOL: II.p-AMINOPHENYLALANINE AS A PRECURSOR OF THEp-NITROPHENYLSERINOL MOIETY
Authors: Siddiqueullah M. , McGrath R. , Vining L. C. , Sala F. , Westlake D. W. S.
Published: December 2009

DL-p-Aminophenylalanine, DL-p-nitrophenylalanine, DL-threo-phenylserine, DL-phenyllactic acid, DL-p-hydroxyphenyllactic acid, D-phenylalanine, L-phenylalanol, DL-threo-β-phenylglyceric acid, D-threo-p-aminophenylserinol, and D-threo-p-nitrophenylserinol, all specifically labeled with14C, were tested as precursors of chloramphenicol in cultures of Streptomyces sp. 3022a. Only DL-p-amino-phenylalanine-α-14C was efficiently incorporated into the p-nitrophenylserinol moiety of the antibiotic. All of the radioactivity was found in the aminomethine carbon. Protein phenylalanine and tyrosine were only weakly labeled, and it is concluded that p-aminophenylalanine is a specific precursor of chloramphenicol.
ACCUMULATION DES ACIDES AMINES LIBRES DANS LE MESOCARPE DE L'OLIVE APRES CONSERVATION A BASSE TEMPERATURE
Authors: Sawas-Dimopoulou Christiane , Fytizas E.
Published: December 2009

not available
Monovalent cations and mitochondrial ATPase activity
Authors: Cereijo-Santaló Roberto
Published: December 2009

The effect of monovalent cations on the ATPase activity of rat liver mitochondria was studied.It was found that alkali-metal ions can activate ATPase when mitochondria become permeable to them by treatment with surface-active agents such as Triton-X-100, alcohols, valinomycin, gramicidin, 2,4-dinitrophenol.The alteration of mitochondrial permeability produced by progressive acidification of the incubation medium indicates that the ability of alkali-metal ions to penetrate mitochondria increases in the order: Li+, Na+, K+, Rb+, and Cs+, which is the order of the decreasing hydrated ionic radii.The results obtained in the presence of valinomycin or gramicidin were comparable with those reported by other workers for the exchange cation–H+. A Na+-activated ATPase could be observed in the presence of high concentrations of valinomycin.The action of surface-active agents on ATPase activity was dependent upon the presence of monovalent cations.It is concluded that control of the metabolism of mitochondria can be exerted through changes in their permeability to cations present in the extramitochondrial cytoplasm.
Inverse relationship of hepatic copper and iron concentrations in rats fed deficient diets
Authors: Sourkes T. L. , Lloyd K. , Birnbaum H.
Published: December 2009

Young male albino rats were fed a diet based upon equal parts of skim milk powder and corn starch. Dietary supplements included cupric sulfate, ferrous sulfate, both salts, or neither. Rats consuming the iron-deficient diet accumulated high concentrations of copper in the liver, a process that became evident only after 7–8 weeks. The rats fed the copper-deficient diet accumulated excessive amounts of iron, beginning much earlier. The hepatic concentrations of copper and iron in these experiments were inversely correlated (P < 0.01) in a complex relationship.
Phosphonolipids. XVI. An alternative method for the synthesis of phosphonic acid analogues of L-α-cephalins
Authors: Baer Erich , Basu Hemendra
Published: December 2009

The preparation of phosphonic acid analogues of α-cephalins by phosphonylation of D-α,β-diglycerides with (2-N,N-dibenzylaminoethyl)phosphonic acid monochloride instead of (2-phthalimidoethyl)-phosphonic acid monochloride, and removal of the protective benzyl groups of the diacyl α-glyceryl-(2-N,N-dibenzylaminoethyl)phosphonates by catalytic hydrogenolysis is described. A simplified procedure for the preparation of 2-bromoethylphosphonic acid is reported.
Effect of 17α-methyltestosterone on steroid formation by rat adrenal tissue
Authors: Rembiesa Roman , Young Peter C. M. , Saffran M.
Published: December 2009

The addition of 17α-methyltestosterone to rat adrenals suppressed the conversion of 4-14C-labeled progesterone and 11-deoxycorticosterone to the corticosteroids, including corticosterone, 18-hydroxy-11-deoxycorticosterone, aldosterone, and more polar substances, such as 18-hydroxycorticosterone. The inhibition depended upon the dose of 17α-methyltestosterone; the formation of substances with the polarity of aldosterone or greater were most sensitive. The 17α-methyltestosterone appears to act as a competitive substrate for the adrenal hydroxylating enzymes because it is itself metabolized to more polar products. The main product, 11β-hydroxy-17α-methyltestosterone, did not appear to inhibit hydroxylation significantly.
Properties of turpentine relative to the effects on fowl plasma in vitro. I. The simulation of "leukemic" changes in normal plasma
Authors: Darcel C. le Q. , Bide R. W. , Merriman Mohendra
Published: December 2009

The addition of some turpentines to avian plasma in vitro caused α-lipoprotein changes similar to those seen in electropherograms of plasma from birds affected with erythroblastosis. The effective turpentines were old oxidized samples containing large amounts of acids and peroxides. Acids, pure peroxides, and cationic soaps had similar effects on plasma but much more material was required. Neither the acids nor the peroxides could be shown to be the cause of the plasma changes but their presence was indicative of activity of turpentine on plasma lipoproteins. The α-lipoprotein changes which appear to result from many different treatments are discussed in terms of possible common mechanisms.
A computer simulation of the effect of ethylene on mitochondrial oxidative phosphorylation
Authors: Olson A. O. , Spencer Mary , Svrcek W. V.
Published: December 2009

A digital computer program capable of solving the differential equations outlining models of oxidative phosphorylation was written and used to study the effect of ethylene on mitochondrial respiration, a phenomenon that could not be studied by direct laboratory experiment. The simulation suggested that the increase in adenosine triphosphate hydrolysis that occurs when mitochondria are treated with ethylene would be sufficient to cause a major increase in mitochondrial, and hence cellular, respiration.
Biosynthesis of renal protein in aminonucleoside nephrosis
Authors: Nicholls D. M.
Published: December 2009

The incorporation of labelled amino acids into microsomal and soluble protein was measured in homogenate fractions of liver and kidney cortex of control and aminonucleoside nephrotic rats. In both the control and the nephrotic rat preparations, the incorporation was higher in liver than in kidney homogenate fractions. In nephrotic rat preparations compared to control rat preparations, there was a large increase in the incorporation of labelled amino acids into kidney protein and a smaller increase in the incorporation into liver protein. This increase in the incorporation of amino acids was found in the microsomal fraction rather than in the soluble fraction, but it depended upon alterations in both the microsomal and soluble fractions obtained from nephrotic kidney. The increase could not be explained by increased endogenous amino acids in nephrotic preparations. A differential inhibitory effect of high levels of guanosine triphosphate on the incorporation of L-leucine-U-14C into ribosomal protein in ceil-free systems was observed and was more pronounced in ribosomal preparations from kidney of aminonucleoside nephrotic rats.
The effect of cobalt ions on energy metabolism in the rat
Authors: Wiberg G. S.
Published: December 2009

Cobalt treatment for 8 days significantly depressed respiration of isolated rat heart mitochondria when citrate or α-ketoglutarate but not succinate was utilized as added substrate. The depressed respiration of the cardiac mitochondria in citrate media was accompanied by an increased accumulation of α-ketoglutarate in the incubation media. Cobalt treatment also reduced the ferricyanide-linked ketoglutarate dehydrogenase activity of isolated rat heart mitochondria. For the first 3 days, isolated diaphragm segments from cobalt-treated rats utilized glucose and pyruvate at rates higher than the controls but respired at reduced rates if ketoglutarate or octanoate was used as the substrate. After 4 days of cobalt-treatment, oxygen uptake was consistently lower in diaphragm segments for all four substrates and remained so for the next 3 days of treatment. By contrast, heart slices from cobalt-treated rats had a consistently lower oxygen uptake for glucose, pyruvate, α-ketoglutarate, and octanoate, commencing with the first day of cobalt injection and continuing for the next 7 days. Significant differences were found in resting glycogen (decreased), glucose uptake (increased), and glycogen deposition (decreased) in isolated diaphragm taken from cobalt-treated rats. Cobalt treatment had no effect on blood pyruvate and lactate levels.
An optical rotatory dispersion study on fibrinogen and some of its derivatives
Authors: McCubbin William D. , Kay Cyril M.
Published: December 2009

Visible and ultraviolet optical rotatory dispersion measurements were carried out on native fibrinogen and some of its derivatives. The latter include: (1) desialicized fibrinogen, (2) a large fragment of the fibrinogen molecule produced by short tryptic digestion, (3) fibrin monomer, and (4) intermediate fibrin polymers produced by the controlled thrombin proteolysis of fibrinogen. The α-helical content of native fibrinogen was deduced as 32%, and empirical calculations suggest that there is about 14% β-structure in the molecule. Sialic acid plays no significant role in the maintenance of the secondary and tertiary structure of the native molecule. No major conformational change is associated with the thrombin proteolysis of fibrinogen, although a small increase in helical content (~5%) accompanies the staggered overlap association of fibrin monomers. The "core" resulting from the controlled tryptic digestion of fibrinogen undergoes a molecular rearrangement relative to the native molecule, such that it possesses a lower α-helical content (24%) and a higher β-form value (23%). In addition, some of the additional tyrosines in the core become encompassed in regions of greater asymmetry to give rise to small aromatic Cotton effects centered around 285 mμ.
Oxidative phosphorylation in Escherichia coli
Authors: Bragg P. D. , Hou Cynthia
Published: December 2009

A particulate fraction obtained from sonic extracts of Escherichia coli was able to carry out oxidative phosphorylation with NADH2 as substrate and to perform the energy-dependent transhydrogenase reaction. The latter activity was more stable, suggesting that different coupling factors were involved in both systems. A coupling-factor preparation stimulated both reactions but to differing degrees. Oxidative phosphorylation was more sensitive than the transhydrogenase to irradiation with ultraviolet light, which destroyed a site located between flavin and cytochrome b1 in the respiratory chain. Experiments with dicumarol and pentachlorophenol suggested that these inhibitors and the coupling-factor preparation also interacted with the electron-transport chain at this site. Further evidence for the existence of two sites of energy coupling was obtained by the selective inhibition of the transhydrogenase by carbonyl cyanide m-chlorophenylhydrazone, EDTA, triiodothyronine, 2,4-dinitrophenol, and hydroxylamine. The effects of calcium and of phosphate ions were consistent with the involvement of non-phosphorylated high-energy intermediates in oxidative phosphorylation and the energy-dependent transhydrogenase.
The stability of acid-soluble chromosomal proteins from avian erythrocytes
Authors: Vidali G. , Neelin J. M.
Published: December 2009

The stability of avian erythrocyte histones was examined under the conditions of extraction, chromatography, electrophoresis, and storage, in order to avoid degradation during these operations. Since turbidity in trichloroacetic acid (TCA) was used as a measure of histone integrity, optimal conditions for quantitative assay were established as follows. One volume of histone sample was mixed with five volumes of 1.1 M TCA at room temperature, and the optical density at 400 mμ was measured after 25 min. The relation between turbidity and protein concentration was linear from 0.03 to at least 0.3 mg histone per milliliter and was not related to the kind of histone, except for the lysine-rich fraction which showed slightly less specific turbidity. Under these conditions turbidity was not sensitive to concomitant solutes such as guanidinium chloride, acetic acid, and dilute buffers and acids.With turbidity as the criterion of protein integrity, it was confirmed that brief manipulation in the cold is desirable in most media, including the dilute acids used for extraction. Nevertheless, chromatography at room temperature in concentrated solutions of guanidinium chloride or acetic acid appears to be tolerably safe. The effect of these conditions of manipulation and storage on histone fractions was substantiated by chromatography and starch-gel electrophoresis. Prolonged extraction of avian erythrocyte nuclei at acid pH released additional non-histone basic protein without alteration of authentic histone fractions.
Microheterogeneity of human serum albumin: evidence for differences in reducibility of disulfide linkages
Authors: Habeeb A. F. S. A.
Published: December 2009

Studies were designed to determine the causes of the microheterogeneity of human serum albumin. Human serum albumin in 3 M KCl was fractionated in a stepwise manner by lowering the pH. The resultant fractions showed similarities in: (a) the reactivity of ε-amino groups with trinitrobenzenesulfonic acid, (b) the binding of sodium dodecyl sulfate to the free amino groups, and (c) the ability to precipitate with anti-human serum albumin. Conversely, differences existed in the susceptibility to reduction of disulfide bonds of the various fractions with β-mercaptoethanol, which suggested that the microheterogeneity of human serum albumin and its fraction may be due, in part at least, to differences in the pairing of the disulfide bonds.
Molecular heterogeneity of a pig serum low-density lipoprotein
Authors: Janado M. , Martin W. G.
Published: December 2009

Low-density serum lipoproteins are heterogeneous in physical and chemical properties. A single low-density lipoprotein component (LDL1) was isolated from pig serum and separated into six fractions in a density gradient. The protein content of the fractions ranged from 16 to 33% as the gradient increased in density, with corresponding changes in lipid content. The molecular weight of the fractions varied with lipid content but the protein moiety remained constant in size (6.4 × 105) in all fractions. It appeared that the lipid composition of each fraction was similar and that heterogeneity in LDL1 is a result of change in lipid amount only. LDL1 molecules of 3.1 × 106 molecular weight were most abundant and the molecular weight ranged from about 1.9 × 106 to 3.8 × 106.
The effects of vitamin E, selenium, lard, and corn oil on lipids in rat serum, muscles, and testes
Authors: Dicks-Bushnell Martha W. , Andrews Roxanne L. , Laughrey Nancy L.
Published: December 2009

Interrelationships among selenium, vitamin E, saturated and unsaturated fat in lipid metabolism in the rat were studied. Weanling and 7-week-old rats were fed diets containing 18% tocopherol-stripped corn oil or lard with 30% Torula yeast. Weanling rats were fed commercial corn oil with Torula yeast for 16 weeks. Supplements of α-tocopherol or selenium prevented liver necrosis and muscular dystrophy, but only α-tocopherol prevented hemolysis of erythrocytes by hydrogen peroxide. Hemolysis of erythrocytes by hydrogen peroxide was the more sensitive index of tocopherol deficiency. The rats started at 7 weeks of age had no liver necrosis and lower levels of creatinuria at the end of the experimental periods than the rats started at weaning.Commercial corn oil did not contain sufficient vitamin E to prevent peroxide hemolysis in the weanling rat. Selenium acted as a growth and food-consumption stimulant only in the rats fed commercial corn oil. Supplements of selenium caused a reduction in serum cholesterol, and in the rats fed commercial corn oil, decreases in other serum lipids and an increase in testes phospholipid. Stripped lard caused an increase in serum phospholipid over that of stripped corn oil. Cholesterol metabolism was altered in muscles of rats with increased creatinuria.
Liver and erythrocyte L-aspartate : and L-alanine : 2-oxoglutarate aminotransferases of the pyridoxine-deficient rat
Authors: Radhakrishnamurty R. , Sabry Z. I.
Published: December 2009

The withdrawal of pyridoxine from the diet of male weanling rats did not appear to affect the liver mitochondrial L-aspartate : 2-oxoglutarate aminotransferase, but the isoenzymes in the liver supernatant and in the erythrocyte showed gradual lowering of activity. The liver L-alanine : 2-oxoglutarate aminotransferase activity (mostly residing in the supernatant) showed a sharp and immediate decline, and that of the erythrocyte exhibited a more gradual decline with the progress of deficiency.The liver supernatant and erythrocyte aspartate aminotransferases of the deficient animals showed a marked recovery with subcutaneous injection of pyridoxine and in vitro addition of pyridoxal-5-phosphate to the enzyme system. The data emphasize the sensitivity of the supernatant and erythrocyte aspartate aminotransferases in reflecting the pyridoxine nutritional state of the rat.
Protein–carbohydrate interaction. XV. The role of bivalent cations in concanavalin A – polysaccharide interaction
Authors: Agrawal B. B. L. , Goldstein I. J.
Published: December 2009

Extensive dialysis of concanavalin A solution against 1.0 M acetic acid results in the loss of its ability to precipitate specific polysaccharides. This activity is restored upon the addition of bivalent cations such as Mg2+, Mn2+, Ca2+, Co2+, and Zn2+. An optimum range of the cation concentration is observed for the activation of metal-free concanavalin A. High concentrations of bivalent cations (> 0.05 M) are inhibitory to the interaction of concanavalin A with specific polysaccharides. Of all the metals tested, Mn2+ appears to be bound most strongly. Urea and guanidine-HCl cause the inhibition of polysaccharide-precipitating activity of concanavalin A, probably by virtue of their unfolding effect on the protein structure.
Reversal of mitochondrial swelling associated with fatty acid oxidation. II. Effects of cytochrome c and carnitine on contraction of fatty acid swollen mitochondria
Authors: Nakatani Misako , McMurray W. C.
Published: December 2009

Rat liver mitochondria undergo reversible swelling in the presence of a fatty acyl CoA generating system. Contraction of the swollen mitochondria was observed on the addition of either carnitine or cytochrome c. At low concentrations the two agents acted synergistically. At high concentrations cytochrome c completely replaced the requirement for carnitine.Cytochrome c also promoted the contraction of mitochondria swollen in the presence of fatty acid alone, provided that either ATP or ADP was added to initiate the contraction. The stimulation by cytochrome c was greater in the presence of ADP, and the contraction was more sensitive to respiratory inhibitors or dinitrophenol but was less sensitive to oligomycin than in the presence of ATP. Studies of the metabolism of 14C-labelled palmitate during cytochrome c induced contraction showed that decreases in mitochondrial-bound fatty acid and corresponding increases in water-soluble metabolites coincided with the reversal of swelling. The results indicated that the energy requirement for mitochondrial contraction in the presence of cytochrome c was provided by generation of high-energy intermediates coupled to oxidation of the fatty acid swelling agent.
Analysis of 2-amino-2-deoxyhexoses by gas–liquid partition chromatography
Authors: Perry M. B. , Webb Ann C.
Published: December 2009

2-Amino-2-deoxyhexoses can be analyzed by gas–liquid partition chromatography of their 2-acet-amido-1,3,4,5,6-penta-O-acetyl-2-deoxyglycitol derivatives prepared by borohydride reduction of the aminoglycoses followed by acetylation of the resulting aminoglycitols with acetic anhydride in the presence of sodium acetate.
The effect of ligand binding and acid splitting on the optical rotatory dispersion of ferric horseradish peroxidase
Authors: Ellis William D. , Dunford H. Brian
Published: December 2009

The optical rotatory dispersion of horseradish peroxidase and its cyanide, fluoride, and hydroxide complexes was studied in the spectral region 215–450 mμ, and that of the azide complex at 350–450 mμ. The effect that splitting the heme from the protein of peroxidase has on the optical rotatory dispersion in the 215–450 mμ region was also studied. Results of measurements of the reduced mean residue rotation at 233 mμ, lead to the conclusion that there are no significant changes in gross protein conformation upon the binding of ligands to peroxidase, but that the splitting of the heme causes a reduction of the helical content of the protein. Pure peroxidase was estimated to have 43% α-helical content, which was reduced to 33% when the heme was split from the protein. Results of studies in the Soret region indicate that the binding of various ligands does not cause an alteration of the geometry of the heme with respect to the protein moiety.
Dicoumarol biosynthesis: origin of the methylene bridge
Authors: Spring M. S. , Stoker J. R.
Published: December 2009

The origin of the methylene-bridge carbon atom of dicoumarol was investigated. In the absence of exogenous formaldehyde, Penicillium jenseni converted o-coumaric acid to 4-hydroxycoumarin but little dicoumarol was produced. Further experiments with potential C1 donors such as choline, serine, and methionine confirmed that dicoumarol was probably an artefact produced by reaction between microbiologically formed 4-hydroxycoumarin and exogenous formaldehyde.
Fractionation of hordein by preparative, continuous carrier-free electrophoresis
Authors: Ivanov Ch. , Mesrob B. , Prusik Z.
Published: December 2009

Barley hordein was fractionated by preparative, continuous carrier-free electrophoresis. Six fractions were obtained, one of which was in negligible quantity. Three of the fractions gave single symmetrical peaks. The amino acid content and the N-terminal amino acid residues of these fractions were determined. The ratios of basic to acidic amino acids showed that the fractions contained different protein substances. The most basic fraction, representing 10% of the total hordein, appeared to be pure since it contained only alanine as a N-terminal amino acid.
A biophysical basis of ligand-induced activation of excitable membranes and associated enzymes. A thermodynamic study using acetylcholinesterase as a model receptor
Authors: Belleau B. , Lavoie J. L.
Published: December 2009

A biophysical analysis of current models for the molecular mechanism of ligand activation of receptors and regulatory enzymes is offered. Acceptance of the working hypothesis that the resting state Pr of the receptor is formally in thermodynamic equilibrium with an energized state Pe allows the prediction that the role of activator ligands should be to modulate that physical variable which controls the relative ground-state conformational energies of the two states. It is pointed out that for a majority of ligands nonexclusive binding is probably operative. The use of acetylcholinesterase (AChE) as a model receptor led to the finding that for some 30 ligands of the tetramethylammonium ion (TMA) series, the parameter ΔF binding is constant at −4.2 ± 0.6 kcal/mole, while the thermodynamic parameters ΔH and ΔS undergo large but compensated fluctuations. The additivity of ΔH and ΔS gives rise to an isoequilibrium relationship of slope β = 288 °K in agreement with an interaction mechanism where a ligand-induced release of "ice-like" water from the binding cleft is operative. Previous criticisms of the physical significance of isoequilibrium relations are shown to be largely inapplicable to the problem under consideration. The interaction mechanism is in accordance with the equation[Formula: see text]where ΔF = ΔHint = −4.15 kcal/mole (the ion–ion interaction), TΔSint = 0, and ΔHext = ΔSext = variable endothermic release of "ice-like" water molecules. It is shown that the TMA ligands strongly modulate the ΔHext–ΔSext couple. Since the release of peptide-bound water molecules is tantamount to a conformational change, it is concluded that the ligands stabilize in varying degrees of efficiency a predetermined conformational state (Pe) of the protein. The conclusion is reached that the ligand-induced perturbation theory of drug action and the induced-fit theory of enzyme action are valid at least in the physical sense.The parameters ΔHext and ΔSext are shown to be additive functions of the molar volume, the intrinsic flexibility, and the physical properties of the ligands. Large anomalous effects of structure and optical isomerism on ΔHext and ΔSext appear to correlate in some manner with high pharmacological potency. It is concluded that a ligand-induced modulation of the physical variable of ice melting from the binding cleft may control the position of the conformational equilibrium between the resting state Pr and the energized state Pe of the receptors.