bluuebunny/crossref_metadata_2025 huggingface dataset:
Ornithine decarboxylase activity and: [125I]iododeoxyuridine incorporation in rat prostate
Authors: Fuller D J , Donaldson L J , Thomas G H
Published: August 2015

The relationship between ornithine decarboxylase activity and [125I]iododexyuridine incorporation was studied in prostates from castrated rats (aged 5, 26 and 80 weeks) injected daily with testosterone for up to 10 days. The results suggest that ornithine decarboxylase activity is a parameter of secretory activity, rather than growth, in the ventral prostate. In the dorsolateral prostate, ornithine decarboxylase activity tends to parallel [125I]iododeoxyuridine incorporation.
Proteoglycans of hyaline cartilage: Electron-microscopic studies on isolated molecules
Authors: Thyberg J , Lohmander S , Heinegård D
Published: August 2015

Proteoglycan monomers from guinea-pig costal cartilage, bovine nasal and bovine tracheal cartilage were observed in the electron microscope after being spread in a monomolecular layer with cytochrome c. The proteoglycan molecule appeared as an extended central core filament to which side-chain filaments were attached at various intervals. The molecules from the three sources displayed great ultrastructural similarities. On average, the core filament was about 290 nm long, there were about 25 side-chain filaments per core filament, the side-chain filaments were about 45 nm long, and the distance between the attachment points of the side-chain filaments to the core filament was about 11 nm. With regard to the overall size of the molecules, no evidence of distinct subpopulations was obtained. Good correlation was found between ultrastructural data for the proteoglycan molecules and chemical data obtained by enzyme digestions and gel chromatography. Together these data strongly support the interpretation of the electron-microscopic pictures as indicating a central filament corresponding to the protein core and side-chain filaments corresponding to the chondroitin sulphate chain clusters of the proteoglycan monomers.
Differential effects of temperature on a membrane adenosine triphosphatase and associated phosphatase
Authors: Walker J A , Wheeler K P
Published: August 2015

Arrhenius plots of a membrane (Na+ + K+)-dependent ATPase (adenosine triphosphatase) activity showed characteristic discontinuities, whereas those of the associated K+-dependent phosphatase activity did not. These findings support the contention that the phosphatase activity does not depend on phospholipid in the same way as does the ATPase activity.
The action of chelating agents on human liver aldehyde dehydrogenase
Authors: Sidhu R S , Blair A H
Published: August 2015

Human liver aldehyde dehydrogenase was inhibited by aromatic chelating agents. However, structurally related compounds with much lower metal-complexing ability displayed affinities for enzyme essentially equal to those of their respective chelating analogues. Inhibition was competitive with respect to the coenzyme. It is suggested that hydrophobic interactions between the inhibitors and the coenzyme-binding site of the enzyme are responsible for the observed effects on activity.
Dogfish M4 lactate dehydrogenase: reversible inactivation by pyridoxal 5′-phosphate and complete protection in complexes that mimic the active ternary complex
Authors: Chen S S , Engel P C
Published: August 2015

Dogfish M4 lactate dehydrogenase, like the corresponding pig enzyme, is inactivated by pyridoxal 5′-phosphate through modification of a single essential lysine residue. The activity is completely protected in the complexes E-NAD+-oxalate, E-NADH-oxamate and E-(NAD+-pyruvate adduct), but only partially protected in E-NAD+, E-NADH, E-NAD+-oxamate and E-NADH-oxalate.
A 30 S precursor of 30 S ribosomes in a mutant of Escherichia coli
Authors: Markey F , Wild D G
Published: August 2015

Escherichia coli 15-28, a mutant with a defect in ribosome metabolism, accumulates a ribonucleoprotein particle that is indistinguishable from 30S subunits by sedimentation but contains the precursor form of 16S RNA. This particle is probably a precursor of 30 S ribosomes.
Fractionation of chick oviduct chromatin. Nuclease-resistant deoxyribonucleic acid
Authors: Krall J F , Socher S H , Van N T , O'Malley B W
Published: August 2015

Chromatin isolated from several chick tissues was treated with micrococcal nuclease. A limited degree of tissue specificity of chromatin DNA resistance to nuclease digestion was observed. No difference in the extent of nuclease resistance of chromatin DNA was detected during oestrogen-induced oviduct differentiation. This suggested that the amount of non-histone chromosomal protein does not play an important role in the sensitivity of chromatin DNA to nuclease digestion. Studies of nuclease resistance of chromatin DNA after dissociation and reconstitution of chromatin proteins and ethanol extraction of chromatin indicate that the histones protect the DNA from nuclease attack. Slow thermal denaturation of nuclease-resistant DNA suggests that the protected DNA sequences may be (A+T)-rich, and the (G+C)-rich satellites present in total chick DNA are sensitive to nuclease.
Purification and characterization of a collagenase extracted from rabbit tumours
Authors: McCroskery P A , Richards J F , Harris E D
Published: August 2015

A collagenase was purified from homogenates of V2 ascites-cell carcinoma growing in rabbit muscle. (NH4)2SO4 precipitation, ion-exchange and gel-filtration chromatography, and affinity chromatography (by using the CB7 CNBr) cleavage fragment of α1(I) collagen linked to agarose) gave a 268000-fold purification and a sevenfold increase in total enzyme units recovered. The specific activity, defined as μmol of collagen in solution cleaved/h per mg of enzyme at 35°C, WAS 1.74.2. The collagenase had a broad pH optimum from pH7.0 to 9.5, and a mol.wt. of between 33000 and 35000. It was inhibited by dithiothreitol, L-cysteine, D-penicillamine, EDTA and 1,10-phenanthroline, and by both rabbit and human serum. 3. Removal of cations by a chelating resin (Chelex 100) produced as inactive enzyme that could be reactiviated by the addition of Ca2+ ions at concentrations as low as 1μM. Other bivalent cations were not effective. 4. The purified collagenase cleaved peptides α2 and α1-CB7 (denatured polypeptides of collagen) at 37 degrees C at one site only. [α1 (I)]2α2 and [α1(III)]3 collagens in solution were cleaved at the same site approximately five times more rapidly than [α1 (II)]3. 5. An inhibitor of the enzyme in the tumour extracts, which was dissociable from the enzyme at the (NH4)2SO4 precipitation step of purification, had a mol. wt. of between 40000 and 50000 but was distinct from the α1 trypsin inhibitor. 6. Studies with zonal density-gradient centrifugation suggested that the enzyme was bound to fibrillar substrate (collagen) extracellularly, but that it was not associated with enzymes originating in cell mitochondria, microsomal preparations or lysosomes.
Effects of sulphate-limited growth in continuous culture on the electron-transport chain and energy conservation in Escherichia coli K12
Authors: Poole R K , Haddock B A
Published: August 2015

Growth of Escherichia coli K12 in a chemostat was limited by sulphate concentrations lower than 300 muM. The synthesis of extracellular polysaccharide and a change in morphology accompanied sulphate-limited growth. Growth yields with respect to the amount of glycerol or oxygen consumed were sixfold and twofold lower respectively under these conditions than when growth was limited by glycerol. Sulphate-limited cells lacked the proton-translocating oxidoreduction segment of the electron-transport chain between NADH and the cytochromes, and particles prepared from these cells lacked the energy-dependent reduction of NAD+ by succinate, DL-α-glycerophosphate or D-lactate, suggesting the loss of site-I phosphorylation. Glycerol-limited cells contained cytochrome b556, b562 and o, ubiquinone and low concentrations of menaquinone. Sulphate limitation resulted in the additional synthesis of cytochromes d, a1, b558 and c550; the amount of ubiquinone was decreased and menaquinone was barely detectable. Non-haem iron and acid-labile sulphide concentrations were twofold lower in electron-transport particles prepared from sulphate-limited cells. Recovery of site-I phosphorylation could not be demonstrated after incubating sulphate-limited cells with or without glycerol, in either the absence or presence of added sulphate. The loss of site-I phosphorylation in sulphate-limited cells is discussed with reference to the accompanying alterations in cytochrome composition of such cells. Schemes are proposed for the functional organization of the respiratory chains of E. coli grown under conditions of glycerol or sulphate limitation.
The biosynthesis of alginic acid by Azotobacter vinelandii
Authors: Pindar D F , Bucke C
Published: August 2015

The sequence of reactions by which alginic acid is biosynthesized from sucrose in Azotobacter vinelandii was determined both by feeding radioactive individual enzymes involved. Results indicate that the first polymeric substance formed in the synthesis is polymannuronic acid and that mannuronic acid units are epimerized to guluronic acid at the polymer level. Guluronic acid does not appear to be formed at the monomer level, either free or in combination with GDP.
Characterization of the terminal stages of chlorophyll (ide) synthesis in etioplast membrane preparations
Authors: Griffiths W T
Published: August 2015

1. Chlorophyll (ide) formation from protochlorophyll (ide) that is normally inactive was demonstrated in etioplast membranes isolated from maize and barlley plants, the process being dependent on intermittent illumination and the addition of NADPH. 2. The addition of NADPH to the membranes was shown to result in the conversion of inactive protochlorophyll (ide) absorbing at about 630 nm into a form(s) with light-absorption maxima at about 640 and 652 nm, both of which disappear when chlorophyll (ide) is formed on illumination. 3. The temperature-dependence of the activation process and its response to a variety of reagents were examined. From these, the conclusion is drawn that -SH groups are involved in the activation but in the active complex these are unavailable for reaction with -SH reagents. 4. Evidence is presented for the occurrence of glucose 6-phosphate dehydrogenase activity within etioplasts and the suggestion is made that the oxidative pentose phosphate pathway can provide the NADPH required for chlorophyll biosynthesis during the early stages of greening.
The activation of non-phosphorylating electron transport by adenine nucleotides in Jerusalem-artichoke (Helianthus tuberosus) mitochondria
Authors: Sotthibandhu R , Palmer J M
Published: August 2015

In isolated plant mitochondria the oxidation of both succinate and exogenous NADH responded in the expected manner to the addition of ADP or uncoupling agents, and the uncoupled rate of respiration was often in excess of the rate obtained in the presence of ADP. However, the oxidation of NAD+-linked substrates responded in a much more complex manner to the addition of ADP or uncoupling agents such as carbonyl cyanide p-trifluoromethoxyphenylhydrazone to mitochondria oxidizing pyruvate plus malate failed to result in a reliable stimulation; this uncoupled rate could be stimulated by adding AMP or ADP in the presence of oligomycin or bongkrekic acid. Spectrophometric measurements showed that the addition of AMP or ADP resulted in the simultaneous oxidation of endogenous nicotinamide nucleotide and the reduction of cytochrome b. ADP was only effective in bringing about these changes in redox state in the presence of Mg2+ whereas AMP did not require Mg2+. It was concluded that AMP activated the flow of electrons from endogenous nicotinamide nucleotide to cytochrome b, possible at the level of the internal NADH dehydrogenase.
Succinate uptake and related proton movements in Escherichia coli K12
Authors: Gutowski S J , Rosenberg H
Published: August 2015

1. The apparent Km values for succinate uptake by whole cells of Escherichia coli K12 depend on pH in the range 6.5-7.4.2. Uptake of succinate in lightly buffered medium is accompanied by proton uptake. 3. The apparent Km values for succinate uptake and for succinate-induced proton uptake are similar. 4. Approximately two protons enter the cell with each succinate molecule. 5. The pattern of inhibition of succinate uptake is similar to that of succinate-induced proton uptake. 6. Uptake of fumarate and malate, which share the succinate-transport system, is also accompanied by the uptake of approximately two protons per molecule of fumarate or malate. 7. Uptake of aspartate by the dicarboxylic acid-transport system is accompanied by the uptake of approximatley two protons per molecule of asparatate. 8. It is concluded that uptake of dicarboxylic acids by the dicarboxylic acid-transport system is obligatorily coupled to proton uptake such that succinate, malate and fumarate are taken up in electroneutral form and asparate is taken up in cationic form. 9. These results are consistent with, though they do not definitely prove, the energization of succinate uptake of the deltapH.
Isolation, composition and reactivity of the neutral glycoproteins from human meconiums with specificities of the ABO and Lewis systems
Authors: Côté R H , Valet J P
Published: August 2015

Blood-group-specific A1, B, AB, H and Lea neutral glycoproteins were isolated from suitable pools of human normal meconiums by a preliminary fractionation with a cationic detergent at pH5 and 9 (borate), followed by ion-exchange and gel chromatography. The ABH materials have sedimentation coefficients of about 10S-11S, whereas the Lea preparation, not strictly homogeneous, shows a coefficient of 7S. From the detailed analytical data collected, the following relations are deduced between these various substances; they all possess a common peptide core; there are stable ratios of N-acetylglucosamine/N-acetylgalactosamine in the B, H and Lea materials and of N-acetylglucosamine/galactose in A, H and Lea materials, from which the numbers of A and B determinants are estimated. In the ABH substances, the ratio of glucosamine to the sum of threonine and serine is stable. Presumably because of genetic factors, the amount of fucose varies among the different glycoproteins, but it is always definitely lower than in the average cyst substances. Various serological tests and precipitin methods were used to measure the potency, purity and integrity of the preparations, including comparisons between A1 and A2 substances from this source. The Leb activity did not appear as high as it is in glycoproteins from adults and a possible interpretation would be the immature Lewis system as observed on erythrocytes; this could explain their very strong inhibiting power towards iso-agglutinins. This family of substances with various specificities has common features with that prepared from ovarian cysts, but differs clearly on some points.
Some observations on the NADP+-linked oxidation of methylglyoxal catalysed by 2-Oxoaldehyde dehydrogenase
Authors: Dunkerton J , James S P
Published: August 2015

In the oxidation of methylglyoxal by 2-oxoaldehyde dehydrogenase, the apparent Km value for NADP+ was about 2.5 times lower than the corresponding Km for NAD+; the apparent Km values for methylglyoxal and for the amine activator L-2-aminopropan-1-ol, with NADP+ as cofactor, were also different from those obtained with NAD+. In the presence of NADP+, the enzyme was not activated by P1, in contrast with the activation of the enzyme when NAD+ was used. The significance of the results is discussed.
Artifacts in the centrifugation of ribosomal and heterogenous ribonucleic acid in “99%-dimethyl sulphoxide” gradients
Authors: Maxwell I H
Published: August 2015

Increasing the total quantity of RNA located on 99%-dimethyl sulphoxide gradients profoundly altered the sedimentation pattern of heterogenous RNA and (to a smaller extent) that of rRNA. Aggregation of small quantities of rRNA with fast-sedimenting heterogenous RNA was also found to occur in these gradients.
Chemical and physical properties of the human urinary glycoprotein with gastric antisecretory activity
Authors: Lugaro G , Pasta P , Casellato M M , Mazzola G , Carrea G
Published: August 2015

The chemical and physical properties of the high-molecular-weight glycoprotein (SO20, w = 8S; Ve=Vo on Sephadex G-200) with gastric antisecretory activity extracted from the urine of pregnant women were studied. Gel filtration in the presence of sodium dodecyl sulphate and sodium dodecyl sulphate/polyacrylamide-disc-gel electrophoresis indicated subunit mol.wts. of 16 000 +/- 1500 and 13 000 +/- 1000 respectively. Reaggregation of the subunits and partial recovery of the biological activity were observed on removal of the detergent. The partial C-terminal sequence was found to be Phe-Tyr-Leu-Val-OH, whereas glycine appears to be the N-terminal amino acid. The carbohydrate composition was examined; all galactosamine was found to be O-glycosidically linked to the polypeptide chain.
The occurrence in amino acid sequences of extensive informational symmetries based on possible codon-codon complementarity in the encoding polynucleotides
Authors: Polya G M , Phillips D R
Published: August 2015

1. A procedure is described for the detection and assessment of informational complementarity in an amino acid sequence; it is based on possible autocomplementarity in the mRNA, and involves codon-to-codon matching. 2. This procedure was applied to myelin basic protein, a variety of protamines, histone IV, silk fibroin, rat skin collagen α1 chain and a sheep keratin. A multiplicity of extensive low-probability informational symmetries, based on codon-to-codon matching, were detected. 3. These low-probability orderings, which are independent of the actual mRNA codons, are rationalized in terms of the evolutionary ordering of the amino acid sequences concerned, in such a way that constraints on the secondary structure of the coding polynucleotides were satisfied. This possible interpretation is supported by a number of significant common properties of the protein sequences analysed.
The effect of polyamines on the synthesis of ribonucleic acid by Drosophila melanogaster larvae
Authors: Byus C V , Herbst E J
Published: August 2015

1. To elucidate further the possible role of polyamines in the synthesis of nuclei acids, a study of the effect of exogenously administered amines on the synthesis of RNA by Drosophila melanogaster larvae was undertaken. This system was chosen because of the previous investigations [Dion, A.S. & Herbst, E.J. (1967) Proc. Natl. Acad. Sci. U.S.A. 58, 2367-2371; Herbst, E.J. & Dion, A.S. (1970) Fed. Proc. Fed. Am. Soc. Exp. Biol. 29, 1563-1567] relating putrescine and spermidine to growth and development of Drosophila.
Synthesis of hepatic polyamines, ribonucleic acid and S-adenosylmethionine in normal and oestrogen-treated chicks
Authors: Eloranta T O , Mäenpää P H , Raina A M
Published: August 2015

1. The hepatic synthesis and accumulation of polyamines, RNA and S-adenosylmethionine were studied in normal and oestrogen-treated immature male chicks. 2. Ornithine decarboxylase activity in chick liver and in whole chick embryo homogenate was preferentially located in the soluble supernatant fraction. 3. In general the activities of the enzymes involved in the synthesis of polyamines and S-adenosylmethionine decreased with increasing age.
Studies on the mechanism of induction of haem oxygenase by cobalt and other metal ions
Authors: Maines M D , Kappas A
Published: August 2015

Cobalt ions (Co2+) are potent inducers of haem oxygenase in liver and inhibit microsomal drug oxidation probably by depleting microsomal haem and cytochrome P-450. Complexing of Co2+ ions with cysteine or glutathione (GSH) blocked ability of the former to induce haem oxygenase. When hepatic GSH content was depleted by treatment of animals with diethyl maleate, the inducing effect of Co2+ on haem oxygenase was significantly augmented. Other metal ions such as Cr2+, Mn2+, Fe2+, Fe3+, Ni2+, Cu2+, Zn2+, Cd2+, Hg2+ and Pb2+ were also capable of inducing haem oxygenase and depleting microsomal haem and cytochrome P-450. None of these metal ions had a stimulatory effect on hepatic haem oxidation activity in vitro. It is suggested that the inducing action of Co2+ and other metal ions on microsomal haem oxygenase involves either the covalent binding of the metal ions to some cellular component concerned directly with regulating haem oxygenase or non-specific complex-formation by the metal ions, which depletes some regulatory system in liver cells of an essential component involved in controlling synthesis or activity of the enzyme.
Arterio-venous differences of choline and choline lipids across the brain of rat and rabbit
Authors: Spanner S , Hall R C , Ansell G B
Published: August 2015

The concentration of unesterified choline in the plasma in the jugular vein of the rat (0.85 nmol/ml) was found to be three times that of the arterial supply to the brain (0.25 nmol/ml), indicating a higher efflux than uptake of unesterified choline by the brain. No such difference was found for the rabbit and no arterio-venous difference for phosphatidylcholine or lysophosphatidylcholine was observed in either species. No arterio-venous difference was found for choline in blood cells. The infusion of [Me-3H]choline into the circulation of the rat or rabbit indicated an uptake of radioactive choline by the brain and an efflux of non-radioactive choline. In the rabbit such an infusion produced a steady rise in the labelling of phosphatidylcholine and lysophosphatidylcholine in the plasma. When [14C2]ethanolamine was injected intraperitoneally into the rat there was a labelling of phosphatidylcholine, lysophosphatidylcholine and sphingomyelin in the plasma and cells of blood from the jugular vein and the arterial supply, as well as in the brain tissue. However, no labelling of unesterified choline in these tissues could be detected. Unesterified choline was shown to be liberated into the plasma when whole blood from the rat or man, but not the rabbit, was incubated for short periods at 30 degrees C.
Protein phosphorylation in respiring slices of guinea-pig cerebral cortex. Evidence for a role for noradrenaline and adenosine 3′:5′-cyclic monophosphate in the increased phosphorylation observed on application of electrical pulses
Authors: Williams M , Rodnight R
Published: August 2015

1. Exposure of slices of cerebral cortex from guinea pigs to electrical pulses for 10s or to noradrenaline, 5-hydroxytryptamine or histamine increases the rate of phosphorylation of unidentified proteins in the tissue; the increases in protein phosphorylation due to electrical pulses and noradrenaline were non-additive, whereas the increases due to pulses and 5-hydroxytryptamine or histamine were additive. 2. The stimulating effects of electrical pulses and noradrenaline on protein phosphorylation were antagonized by the ʲ-adrenergic blocking agents L-propranolol, dichloroisoprenaline, practolol and ICI 66082, but not by the ʱ-adrenergic blocking agents, phentolamine and phenoxybenzamine. 3. The increase in protein phosphorylation associated with electrical pulses was antagonized by 10 μm-trifluoperazine and 0.5 μm-prostaglandin E1. 4. It is postulated that under the experimental conditions used the action of electrical pulses on protein phosphorylation is mediated by noradrenaline acting through a ʲ-adrenergic receptor mechanism probably involving adenylate cyclase.
Inhibition of protein synthesis in reticulocyte lysates by trichodermin
Authors: Carter C J , Cannon M , Smith K E
Published: August 2015

1. The effect of trichodermin as an inhibitor of eukaryotic protein synthesis was studied in a reticulocyte cell-free system. 2. Trichodermin at a concentration of 25 μg/ml inhibits total protein synthesis instantaneously and stabilizes polyribosome profiles. Conversely, at a concentration of 0.25 μg/ml the drug inhibits total protein synthesis by only 70-75% and allows 30-35% breakdown of the polyribosomes in the system. These effects were compared with those produced by two other drugs (pactamycin and anisomycin) examined under conditions identical with those used for trichodermin.
Effect of hyperphenylalaninaemia on lipid synthesis from ketone bodies by rat brain
Authors: Patel M S. , Owen O E.
Published: August 2015

The effect of hyperphenylalaninaemia on the metabolism of ketone bodies in vivo and in vitro by developing rat brain was investigated. The incorporation in vivo of [14C]acetoacetate into cerebral lipids was decreased by both chronic (for 3 days) and acute (for 6h) hyperphenylalaninaemia induced by injecting phenylalanine into 1-week-old rats. In studies in vitro it was observed that the incorporation of the radioactivity from [14C]acetoacetate and 3-hydroxy[14C]butyrate into cerebral lipids was inhibited by phenyl-pyruvate, but not by phenylalanine. Phenylpyruvate also inhibited the incorporation of 3H from 3H2O into lipids by brain slices metabolizing either 3-hydroxybutyrate or acetoacetate in the presence of glucose. These findings suggest that the decrease in the incorporation in vivo of [14C]acetoacetate into cerebral lipids in hyperphenylalaninaemic rats is most likely caused by phenylpyruvate and not by phenylalanine. Phenylpyruvate as well as phenylalanine had no inhibitory effects on ketone-body-catabolizing enzymes, namely 3-hydroxybutyrate dehydrogenase, 3-oxo acid CoA-transferase and acetoacetyl-CoA thiolase, in rat brain. Phenylpyruvate but not phenylalanine inhibited the activity of the 2-oxoglutarate dehydrogenase complex from rat and human brain. These findings suggest that the metabolism of ketone bodies is impaired in brains of untreated phenylketonuric patients, and in turn may contribute to the diminution of mental development and function associated with phenylketonuria.
The formation of alanine from amino acids in diaphragm muscle of the rat
Authors: Goldstein L , Newsholme E A.
Published: August 2015

Alanine production and pyruvate content of the isolated rat hemidiaphragm are increased by isoleucine or glutamate. These results support the hypothesis that amino acids are converted into pyruvate before oxidation and that some pyruvate is transaminated to alanine, which is released from the muscle.
Sodium/proton antiport in brush-border-membrane vesicles isolated from rat small intestine and kidney
Authors: Murer H , Hopfer U , Kinne R
Published: August 2015

Studies on proton and Na+ transport by isolated intestinal and renal brush-border-membrane vesicles were carried out to test for the presence of an Na+/H+-exchange system. Proton transport was evaluated as proton transfer from the intravesicular space to the incubation medium by monitoring pH changes in the membrane suspension induced by sudden addition of cations. Na+ transport was determined as Na+ uptake into the vesicles by filtration technique. A sudden addition of sodium salts (but not choline) to the membrane suspension provokes an acidification of the incubation medium which is abolished by the addition of 0.5% Triton X-100. Pretreatment of the membranes with Triton X-100 prevents the acidification. The acidification is also not observed if the [K+] and proton conductance of the membranes have been increased by the simultaneous addition of valinomycin and carbonyl cyanide p-trifluoromethoxyphenylhydrazone to the K+-rich incubation medium. Either valinomycin or carbonyl cyanide p-trifluoromethoxyphenylhydrazone when added alone do not alter the response of the membranes to the addition of Na+. Na+ uptake by brush-border microvilli is enhanced in the presence of a proton gradient directed from the intravesicular space to the incubation medium. Under these conditions a transient accumulation of Na+ inside the vesicles is observed. It is concluded that intestinal and renal brush-border membranes contain a NA+/H+ antiport system which catalyses an electroneutral exchange of Na+ against protons and consequently can produce a proton gradient in the presence of a concentration difference for Na+. This system might be involved in the active proton secretion of the small intestine and the proximal tubule of the kidney.
Activities of citrate synthase and NAD+-linked and NADP+-linked isocitrate dehydrogenase in muscle from vertebrates and invertebrates
Authors: Alp P R. , Newsholme E A. , Zammit V A.
Published: August 2015

1. The activities of citrate synthase, NAD+-linked and NADP+-linked isocitrate dehydrogenase were measured in muscles from a large number of animals, in order to provide some indication of the importance of the citric acid cycle in these muscles. According to the differences in enzyme activities, the muscles can be divided into three classes. First, in a number of both vertebrate and invertebrate muscles, the activities of all three enzymes are very low. It is suggested that either the muscles use energy at a very low rate or they rely largely on anaerobic glycolysis for higher rates of energy formation. Second, most insect flight muscles contain high activities of citrate synthase and NAD+-linked isocitrate dehydrogenase, but the activities of the NADP+-linked enzyme are very low. The high activities indicate the dependence of insect flight on energy generated via the citric acid cycle. The flight muscles of the beetles investigated contain high activities of both isocitrate dehydrogenases. Third, other muscles of both vertebrates and invertebrates contain high activities of citrate synthase and NADP+-liniked isocitrate dehydrogenase. Many, if not all, of these muscles are capable of sustained periods of mechanical activity (e.g. heart muscle, pectoral muscles of some birds). Consequently, to support this activity fuel must be supplied continually to the muscle via the circulatory system which, in most animals, also transports oxygen so that energy can be generated by complete oxidation of the fuel. It is suggested that the low activities of NAD+-linked isocitrate dehydrogenase in these muscles may be involved in oxidation of isocitrate in the cycle when the muscles are at rest. 2. A comparison of the maximal activities of the enzymes with the maximal flux through the cycle suggests that, in insect flight muscle, NAD+-linked isocitrate dehydrogenase catalyses a non-equilibrium reaction and citrate synthease catalyses a near-equilibrium reaction. In other muscles, the enzyme-activity data suggest that both citrate synthase and the isocitrate dehydrogenase reactions are near-equilibrium.
Effect of heart work and insulin on the incorporation of [14C]glucose into hexose phosphates, uridine diphosphate glucose and glycogen in the normal and insulin-deficient perfused rat heart under working and non-working conditions
Authors: Das I , Chain E B.
Published: August 2015

1. The specific radioactivities of glucose 1-phosphate, glucose 6-phosphate, fructose 6-phosphate, UDP-glucose and glycogen, derived from [14C]gluocose, were determined in the normal and insulin-deficient (streptozotocin-diabetic and anti-insulin-serum-treated) perfused non-working and working rat heart. 2. The specific radioactivities of all glucose metabolities reached a plateau after about 10 min, except that for glycogen, which increased slightly but steadily over the whole observation period of 30min. 3. The specific radio-activities of fructose 6-phosphate, UDP-glucose and glycogen were slignificantly lower in the streptozotocin-diabetic heart than in the normal heart. 4. Mechanical work in the normal rat heart increased the specific radioactivities of glucose 1-phosphate, UDP-glucose and glycogen, but had little or no effect on those of gluose 6-phosphate and fructose 6-phosphate. 5. In the normal heart insulin strongly increased the specific radioactivities of all gluocse metabolites under all conditions tested. The maximum values achieved in the normal working heart in the presence of insulin were only about 15-20% above those in the normal non-working heart in the presence of insulin for the phosphorylated intermediates and about 40% above for glycogen. 6. In the streptozotocin-diabetic heart, work restored the specific radioactivities of all glucose metabolities to about normal values. 7. In the streptozotocin-diabetic heart insulin strongly increased the specific radioactivities of the direct glycogen precursors glucose 1-phosphate and UDP-glucose; the effect of insulin on glucose 6-phosphate and fructose 6-phosphate was less marked. These results confirm previous findings that the primary metabolic lesion in diabetic heart muscle is a defect of glycogen synthesis. The specific radioactivity of glycogen itself was increased sixfold. 8. Under all conditions tested the specific radioactivity of glucose 1-phosphate was always found to be higher than that of glucose 6-phosphate. This indicated either compartmentation of a small but metabolically very active pool of glucose 6-phosphate, or the existence of a hitherto unknown pathway of metabolism in which glucose 1-phosphate is the primary reaction product. For a number of reasons the authors prefer the first explanation, which could also account for the observation that in the perfused normal working and non-working heart the specific radioactivity of fructose 6-phosphate was always found to be higher than that of glucose 6-phosphate. This difference disappeared or was reversed in the rat hearts rendered insulin-insufficent by either streptozotocin or anti-insulin treatment.
N-terminal amino acid sequence of wheat proteins that lack phenylalanine and histidine residues
Authors: Redman D G
Published: August 2015

The 24 residues of the N-terminal CNBr peptide from a wheat albumin, that lacks phenylalanine and histidine, have been sequenced. Three of the assignments were made partly by analogy with two other proteins, as evidence is presented that all three proteins are probably identical in this region. Extra evidence for the sequences of the α-chymotryptic peptides derived from the N-terminal CNBr peptides of the three proteins, and also for their assembly, has been deposited as Supplementary Publication SUP 50063 (11 pages) at the British Library Lending Division, Boston Spa, Wetherby, West Yorkshire LS23 7BQ, U.K., from whom copies may be obtained on the terms given in Biochem J. (1976) 153, 5. The nature of such evidence is stated in the text of this present communication.
Mouse haemoglobin β chains. Sequence data on embryonic γ chain and genetic linkage of the γ-chain locus to the adult β-chain locus Hbb
Authors: Gilman J G
Published: August 2015

Embryonic haemoglobin y-chain types were determined by starch-gel electrophoresis for inbred Mus musculus strains Sec/ReJ and Au/SsJ (with Hbbs and Hbbp adult β-chain alleles respectively) and for random-bred HA/ICR (Swiss) mice, which had been selected to be homozygous for the adult Hbbd β-chain allele. The strain with the Hbbs allele had y1 embryonic β chain and the strain with the Hbbd allele had y2. The strain with the Hbbp allele also had y2 chain. A breeding study showed that the maximum recombination frequency between the Hbb locus and the y-chain locus is 5.4% at the 95% confidence level. Embryonic y2 chain was sequenced for 39 positions from the N-terminus with an Edman-Begg sequenator. Some tryptic-peptide composition data were obtained on both y1 and y2 chains. No amino acid substitutions between y1 and y2 chains were found in the 40 positions for which there are common data on the two chains. y2 and adult β chains are different in 12 of the first 21 positions, but show considerable similarity thereafter. It is suggested that homologous but unequal crossing-over between y-chain and adult β-chain loci could have given rise to the adult β-chain allele Hbbd, which produces structurally different major and minor β chains from two closely linked genes.
The structures of the carbohydrate moieties of the α subunit of human chorionic gonadotrophin
Authors: Kennedy J F. , Chaplin M F.
Published: August 2015

The α subunit of human chorionic gonadotrophin was reduced with dithiothreitol followed by carboxymethylation with iodoacetic acid. The modified glycoprotein was hydrolysed with trypsin to give various peptides, the identities of which were established, and glycopeptides. The glycopeptides were separated by gel filtration and ion-exchange chromatography; they were subjected to component analysis and were found to represent the two carbohydrate moieties in the parent glycoprotein. Sequential removal with glycoside hydrolases of monosaccharide units from the glycopeptides demonstrated (1) that galactose, mannose, glucosamine (2-amino-2-deoxyglucose) and neuraminic acid (5-amino-3,5-dideoxy-glycero-galacto-2-nonulosonic acid) residues possess the D configurations, (2) that the glucosamine units are N-acetylated and (3) the order of the monosaccharide units in the chain, the neuraminic acid units being furthest from the peptide backbone of the subunit and substituting the D-galactose units. Methylation analysis of the glycopeptides by adaptation of the Hakomori technique demonstrated that: (4) D-galactose, D-mannose and N-acetylglucosamine (2-acetamido-2-deoxy-D-glucose) units exist in the pyranose forms; (5) the D-galactopyranose units are linked in the 1 and 6 positions; (6) the D-mannopyranose units exist in several forms, one in a terminal non-reducing position, one as 1,2-linked residues and some as 1,6-linked branch points; (7) the N-acetylglucosamine units are 1,6-linked. On the basis of the results of methylation and enzymic analysis, structures are proposed for the carbohydrate moieties and the assignments are compared with other data previously obtained by periodate-oxidation studies [Kennedy et al. (1974) Carbohydr. Res. 36, 369-377].
Phosphonomethyl analogues of hexose phosphates
Authors: Webster D , Jondorf W. R , Dixon H B. F.
Published: August 2015

The analogue of fructose 1,6-bisphosphate in which the phosphate group, -O-PO3H2, on C-6 is replaced by the phosphonomethyl group, -CH2-PO3H2, was made enzymically from the corresponding analogue of 3-phosphoglycerate. It was a substrate for aldolase, which was used to form it, but not for fructose 1,6-bisphosphatase. It was hydrolysed chemically to yield the corresponding analogue of fructose 6-phosphate [i.e. 6-deoxy-6-(phosphonomethyl)-D-fructose, or, more strictly, 6,7-dideoxy-7-phosphono-D-arabino-2-heptulose]. This proved to be a substrate for the sequential actions of glucose 6-phosphate isomerase, glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase. Thus seven out of the nine enzymes of the glycolytic and pentose phosphate pathways so far tested catalyse the reactions of the phosphonomethyl isosteres of their substrates.
Removal of adsorbed elastase from partially digested elastin
Authors: Fromageot H P , Slusarczuk G M
Published: August 2015

Bovine ligamentum nuchae elastin that had been partially digested by porcine pancreatic elastase and then thoroughly washed with 0.2 M-NaC1/0.05 M-sodium borate solution continued to release peptide fragments in solution. Complete removal of elastase from the elastin surface required extraction with dilute alkali, a procedure that does not irreversibly inactivate the enzyme or hydrolyse elastin.
The relative importance of muscle protein synthesis and breakdown in the regulation of muscle mass
Authors: Millward D J , Garlick P J , Nnanyelugo D O , Waterlow J C
Published: August 2015

The effects of growth-suppressing and muscle-wasting treatments on muscle protein turnover and amino acid concentrations were determined in vivo. All treatments depressed protein synthesis and some treatments depressed protein breakdown. Only prolonged starvation increased protein breakdown. Muscle protein mass is regulated primarily through alterations in protein synthesis in all except emergency conditions. The increased concentrations of the branched-chain amino acids indicate that they are unlikely to be involved in this regulation.
Transport of pyruvate nad lactate into human erythrocytes. Evidence for the involvement of the chloride carrier and a chloride-independent carrier
Authors: Halestrap A P
Published: August 2015

The kinetics and activation energy of entry of pyruvate and lactate into the erythrocyte were studied at concentrations below 4 and 15mM respectively. The Km and Vmax. values for both substrates are reported, and it is shown that pyruvate inhibits competitively with respect to lactate and vice versa. In both cases the Km for the carboxylate as a substrate was the same as its Ki as an inhibitor. α-Cyano-4-hydroxycinnamate and its analogues inhibited the uptake of both lactate and pyruvate competitively. Inhibition was also produced by treatment of cells with fluorodinitrobenzene but not with the thiol reagents or Pronase. At high concentrations of pyruvate or lactate (20mM), uptake of the carboxylate was accompanied by an efflux of Cl-ions. This efflux of Cl- was inhibited by α-cyano-4-hydroxycinnamate and picrate and could be totally abolished by very low (< 10 µM) concentrations of the inhibitor of Cl- transport, 4,4'-di-isothiocyanostilbene-2,2'-disulphonic acid. This inhibitor titrated out the chlordie efflux induced by pyruvate, bicarbonate, formate and fluoride, in each case total inhibition becoming apparent when approximately 1.2 × 106 molecules of inhibitor were present per erythrocyte, that is, about one inhibitor molecule per molecule of the Cl- carrier. Evan when Cl- efflux was totally blocked pyruvate and lactate uptake occurred. Kinetic evidence is presented which suggests that the Cl- carrier can transport pyruvate and lactate with a high Km and high Vmax., but that an additional carrier with a low Km and a low Vmax. also exists. This carrier catalyses the exchange of small carboxylate anions with intracellular lactate, is competitively inhibited by α-cyano-4-hydroxycinnamate and non-competitively inhibited by picrate. The Cl- carrier shows a reverse pattern of inhibition. It is concluded that net efflux of lactic acid from the cell must occur on the Cl- carrier and involve exchange with HCO3- followed by loss of CO2. The low Km carrier might be used in pyruvate/lactate or acetoacetate/β-hydroxybutyrate exchanges involved in transferring reducing power across the cell membrane. The possibility that the Cl- carrier exists in cells other than the erythrocyte is discussed. It is concluded that its presence in other cell membranes together with a low intracellular Cl- concentration would explain why the pH in the cytoplasm is lower than that of the blood, and why permeable carboxylate anions do not accumulate within the cell when added from outside.
Further characterization of rat liver mitochondrial fractions. Lipid composition and synthesis, and protein profiles
Authors: Satav J G , Katyare S S , Fatterpaker P , Sreenivasan A
Published: August 2015

1. Heavy and light mitochondrial fractions obtained by differential centrifugation were further characterized with respect to their lipid composition and synthesis and protein profiles, as seen by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis. 2. The light mitochondrial fraction was rich in total lipids, phospholipids and cholesterol. The cardiolipin content, however, was low. 3. Rates of [3H]glycerol incorporation into phospholipids of heavy mitochondria and microsomal fractions were almost identical. On the other hand, incorporation into the individual phospholipids in light mitochondria was about 4-6 times higher. Incorporation into cardiolipin of light mitochondria was about 10-fold higher than in the heavy mitochondria. 4. Analysis of protein profiles by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis showed that the pattern obtained for the light mitochondria was similar to that for heavy mitochondria. However, the light fraction was relatively poor in high-molecular-weight proteins and rich in low-molecular-weight proteins. The microsomal protein profile was altogether different. 5. The significance of these findings is discussed in relation to mitochondrial biogenesis.
Effect of ischaemic limb injury on the rates of metabolism of ketone bodies in starved rats
Authors: Barton R N
Published: August 2015

1. Rats starved for 30h were injected with trace amounts of [3-14C]acetoacetate and β-hydroxy[3-14C]butyrate 1h after ischaemic limb injury in a 20 °C environment, and the concentrations and radioactivities of blood ketone bodies were determined at intervals. 2. Starvation alone raised the rates of production and utilization of β-hydroxybutyrate plus acetoacetate about 3.7-fold, but lowered their metabolic clearance rates by about 50%. In the starved rat ketone-body oxidation could account for up to 30% of whole body O2 consumption. 3. Injury in starved rats lowered the rates of production and utilization of both β-hydroxybutyrate and acetoacetate, the combined fall of about 37% slightly exceeding the concomitant fall in whole-body O2 consumption. The concentration of β-hydroxybutyrate decreased after injury, but its metabolic clearance rate was unaltered; the concentration of acetoacetate rose slightly and its metabolic clearance rate fell.
Studies on the biosynthesis of pancreatic glucagon in the pigeon (Columba livia)
Authors: O'Connor K J , Lazarus N R
Published: August 2015

The biosynthesis of glucagon was studied in microdissected pigeon pancreatic, islets. [3H]-Tryotophan and [3H]leucine were incorporated into big and little glucagon. No precursor-product relationship was evident between big and little glucagon after radioactive pulsechase and immunoreactive chase incubations. Radioactive and immunoreactive little glucagon and immunoreactive big glucagon were actively secreted and the synthesis of both glucagons was inhibited by high concentrations of glucose. [3H]Tryptophan and [3H]leucine were incorporated into an islet protein of about 20000mol.wt. Gel filtration of extracts of turkey pancreas revealed the presence of an immunoreactive peak of mol.wt. approx. 20000. This glucagon-immunoreactive component was also present in dog and ox pancreas and was stable to chaotropic agents and elution at various pH values. A similar-sized glucagon-immunoreactive species was present in the dog circulation. These results are discussed in the light of the presently accepted mechanisms of glucagon biosynthesis.
Phospholipid composition of the plasma membrane of the green alga, Hydrodictyon africanum
Authors: Bailey D S , Northcote D H
Published: August 2015

A plasma-membrane fraction was isolated from the alga Hydrodictyon africanum by micro-dissection and its phospholipid components were analysed. Phosphatidylcholine was the major phospholipid of the preparation. Both phosphatidylserine and diphosphatidylglycerol were enriched in the fraction compared with the whole cell, but the relative amount of phosphatidylglycerol present was less than that in the whole cell. Phosphatidylinositol was absent from the plasma-membrane preparation.
Synthesis of bile acid monosulphates by the isolated perfused rat kidney
Authors: Summerfield J A , Gollan J L , Billing B H
Published: August 2015

Perfusion of an isolated rat kidney with labelled bile acids, in a protein-free medium, resulted in the urinary excretion of the labelled bile acid, 3% being converted into polar metabolities in 1h. These metabolities were neither glycine nor taurine conjugates, nor bile acid glucuronides, and on solovolysis yielded the free bile acid. On t.l.c. the metabolite of [24-14C]lithocholic acid had the mobility of lithocholate 3-sulphate. The principal metabolite of [24-14C]chenodeoxycholic acid had the mobility of chenodeoxycholate 7-sulphate; trace amounts appeared as chenodeoxycholate 3-sulphate. [35S]sulphate was incorporated in chenodeoxycholic acid by the kidney, resulting in a similar pattern of sulphation. No disulphate salt of chenodeoxycholic acid was detected. These findings lend support to the hypothesis that renal synthesis may account for some of the bile acid sulphates present in urine in the cholestatic syndrome in man.