bluuebunny/crossref_metadata_2025 huggingface dataset:
Changes in glutaminase activities of rat liver and kidney during pre- and post-natal development
Authors: Linder-Horowitz Maria
Published: August 2015

The activities of two phosphate-dependent glutaminase reactions characteristic of adult rat liver and kidney were determined in these organs from 2½ days before to 7 days after birth and compared with the activities in the adult tissues. In the kidney, before and after birth, only the kidney type of activity was detected, and it increased in concentration in parallel with the steady growth of that organ throughout the period examined. In the liver, however, the kidney type of activity was the only one present 2½ days before birth, and its concentration decreased to barely significant values by the end of the first week after birth. In contrast, the liver type of activity appeared only just before birth and increased to 60% of adult values over the next 4 days. There was no obvious relation between these changes in glutaminase type and changes in liver weight, protein content and total cell number that occurred during this time. But there was a very close correlation between the fall in kidney-type activity and the estimated fall in haematopoietic-cell number in liver.
The reversibility of the Δ8-cholestenol–Δ7-cholestenol isomerase reaction in cholesterol biosynthesis
Authors: Wilton D. C. , Rahimtula A. D. , Akhtar M
Published: August 2015

The incubation of Δ7-cholestenol with a 10000g supernatant or 105000g microsomes in the presence of tritiated water is studied. The reisolated Δ7-cholestenol contained up to 0·67g.atom of tritium/mole. This result can best be explained by assuming the reversibility of the reaction Δ8-cholestenol ⇌ Δ7-cholestenol.
The adenosine triphosphatase and calcium ion-transporting activities of the sarcoplasmic reticulum of developing muscle
Authors: Holland D. L. , Perry S V
Published: August 2015

1. The ATPase (adenosine triphosphatase) specific activity and the total nitrogen content of the myofibrillar fraction per g. wet weight of rabbit longissimus dorsi muscle increased steadily during the late foetal stages and the first few weeks after birth. 2. The ATPase specific activity of the sarcoplasmic-reticular fraction isolated by a sucrose-density-gradient procedure rose to a sharp peak 8–10 days after birth and then declined to the adult value, which was about 25% of the maximum. 3. The peak in ATPase activity was a feature of the sarcoplasmic reticulum isolated from muscle, and the time at which it occurred in relation to birth was related to the degree of development and the activity pattern of the muscle. 4. The peak in ATPase activity of the sarcoplasmic reticulum occurred at an earlier age if newborn animals were made to exercise earlier than was normal. 5. The ‘extra’ ATPase associated with the sarcoplasmic reticulum and the ability to concentrate Ca2+ increased in a similar manner over the period of development studied. 6. It is postulated that the Ca2+-transport system of the sarcoplasmic reticulum consists of two components, namely the ATPase and the system coupling this enzyme to Ca2+ transport. During development the ATPase develops first and has almost reached maximum activity in the longissimus dorsi muscle of the rabbit after 8–10 days. Subsequently the activity of the coupling system rises rapidly, leading to an increase in the capacity and efficiency of Ca2+ transport.
Evaluation of three isotope-dilution techniques for studying the kinetics of glucose metabolism in sheep
Authors: White R. G. , Steel J. W. , Leng R. A. , Luick J. R.
Published: August 2015

1. Comparisons have been made of three isotope-dilution techniques for measuring parameters of glucose metabolism in sheep given their daily ration in 12 equal amounts (i.e. from 07.00 to 18.00hr.) 2. [U−14C]Glucose was used in all experiments. After a single injection the specific radioactivity of plasma glucose was measured at specific times for up to 24hr. Primed infusions were made with various ratios of P, priming injection (nc), to F, infusion rate (nc/min.) (P/F ratios varying from 23:1 to 147:1) and the specific radioactivity of plasma glucose was measured at 60, 120, 150, 180, 210 and 240min. In continuous infusions the specific radioactivity of plasma glucose was followed for 9hr.; a constant specific radioactivity was observed after approximately 180min. 3. A computer programme was used to fit a multi-exponential equation to the log(specific radioactivity)–time curve after a single injection. A second- or third-order exponential equation was found to fit the results. 4. Conventional analyses of all results showed that similar estimates of the irreversible loss of glucose were obtained by using all three techniques. Estimates of glucose pool size and space by using the primed infusion technique were both significantly higher than estimates obtained by the single injection technique. In these experiments total entry rate could only be determined from the single-injection results and a wide variation in estimates was obtained. 5. Comparisons of the specific radioactivity–time relationships after a single injection of [U−14C]glucose in sheep given their ration either once daily or as a proportion at hourly intervals indicated that there were fluctuations in glucose synthesis in the former over the period of the experiment. The multi-exponential curves fitted to these results had larger residual variances than in sheep given food at hourly intervals. All parameters of glucose metabolism estimated were similar under both feeding regimes. 6. A number of methods of analysis are discussed and a model for glucose metabolism in sheep in suggested.
The control of isocitrate oxidation by rat liver mitochondria
Authors: Nicholls D. G. , Garland P. B.
Published: August 2015

1. The factors capable of affecting the rate of isocitrate oxidation in intact mitochondria include the rate of isocitrate penetration, the activity of the NAD-specific and NADP-specific isocitrate dehydrogenases, the activity of the transhydrogenase acting from NADPH to NAD+, the rate of NADPH oxidation by the reductive synthesis of glutamate and the activity of the respiratory chain. A quantitative assessment of these factors was made in intact mitochondria. 2. The kinetic properties of the NAD-specific and NADP-specific isocitrate dehydrogenases extracted from rat liver mitochondria were examined. 3. The rate of isocitrate oxidation through the respiratory chain in mitochondria with coupled phosphorylation is approximately equal to the maximal of the NAD-specific isocitrate dehydrogenase but at least ten times as great as the transhydrogenase activity from NADPH to NAD+. 4. It is concluded that the energy-dependent inhibition of isocitrate oxidation by palmitoylcarnitine oxidation is due to an inhibition of the NAD-specific isocitrate dehydrogenase. 5. Kinetic studies of NAD-specific isocitrate dehydrogenase demonstrated that its activity could be inhibited by one or more of the following: an increased reduction of mitochondrial NAD, an increased phosphorylation of mitochondrial adenine nucleotides or a fall in the mitochondrial isocitrate concentration. 6. Uncoupling agents stimulate isocitrate oxidation by an extent equal to the associated stimulation of transhydrogenation from NADPH to NAD+. 7. A technique is described for continuously measuring with a carbon dioxide electrode the synthesis of glutamate from isocitrate and ammonia.
Completion of the amino acid sequence of papain
Authors: Husain S. S. , Lowe G.
Published: August 2015

Papain was inhibited with bromo[2−14C]acetic acid, the tertiary structure of the inhibited enzyme was unfolded and the disulphide bridges were reduced with mercaptoethanol and aminoethylated. Digestion with trypsin gave a radioactive peptide consisting of residues 18–58 inclusive and containing therefore the sequence of the thirteen unknown residues 29–41 in the primary sequence of papain. This peptide was digested with pepsin to give a radioactive peptide consisting of residues 18–47, which after digestion with 0·4m-hydrochloric acid gave a radioactive peptide consisting of residues 24–43 inclusive. Further digestion with 6m-hydrochloric acid gave peptides that were used to determine the sequence: Ser-Ala-Val-Val-Thr-Ile-Glx-Gly-Ile-Ile-Lys-Ile-Arg for the residues 29–41, so completing the amino acid sequence of papain.
Human small-intestinal β-galactosidases. Separation and characterization of one lactase and one hetero β-galactosidase
Authors: Asp Nils-Georg , Dahlqvist Arne , Koldovský Otakar
Published: August 2015

1. Two β-galactosidases from human small-intestinal mucosa were separated by gel-filtration chromatography and the properties of the two enzymes were studied. Lactose and four hetero β-galactosides were used as substrates. 2. One of the enzymes was particle-bound and could be partially solubilized with papain. Of the substrates hydrolysed by this enzyme, lactose was hydrolysed most rapidly. This enzyme is thus essentially a disaccharidase and is named lactase. It is presumably identical with the ‘lactase 1’ described earlier. 3. The other enzyme was mainly soluble and hydrolysed all artificial substrates used, whereas no lactase activity could be detected. This enzyme has therefore been designated hetero β-galactosidase. 4. p-Chloromercuribenzoate (0·1mm) inhibited the hetero β-galactosidase completely but did not influence the activity of the lactase. Tris was a competitive inhibitor of both enzymes. 5. The residual lactase activity in the mucosa of lactose-intolerant patients may be exerted by a small amount of remaining lactase as such, or possibly by a third enzyme with a more acid pH optimum.
Isomers of glucosaminylphosphatidylglycerol in Bacillus megaterium
Authors: MacDougall J C , Phizackerley P. J. R.
Published: August 2015

1. The lipids of Bacillus megaterium were extracted and three lipids containing glucosamine were identified. One of these is not a phospholipid, but the other two, which differ in their chromatographic behaviour, contain phosphorus, glycerol, fatty acid and d-glucosamine in the molar proportions 1:2:2:1. 2. In both phosphoglycolipids, the fatty acids are bound in ester linkage, and both yield 2,5-anhydromannose and 3-sn-phosphatidyl-1′-sn-glycerol on treatment with sodium nitrite. 3. Both phosphoglycolipids were N-acetylated and, after removal of fatty acids by mild alkaline hydrolysis, in both cases N-acetylglucosamine was quantitatively released by β-N-acetylhexosaminidase. 4. The glucosaminylglycerols derived from the two phosphoglycolipids by partial acid hydrolysis differ in their behaviour towards periodate. In one case 1 mole of periodate is rapidly consumed/mole of glucosaminylglycerol, but in the other case under identical conditions the consumption of periodate is negligible. 5. The phosphoglycolipids were identified as 1′-(1,2-diacyl-sn-glycero-3-phosphoryl)-3′-O-β-(2-amino-2-deoxy-d-glucopyranosyl)-sn-glycerol and as 1′-(1,2-diacyl-sn-glycero-3-phosphoryl)-2′-O-β-(2-amino-2-deoxy-d-glucopyranosyl)-sn-glycerol. 6. Both phosphoglycolipids are good substrates for phospholipase A: neither is a substrate for phospholipase C from Clostridium perfringens, and only the 3′-glucosaminide is a substrate for phospholipase D.
1-Anilinonaphthalene-8-sulphonate, a fluorescent conformational probe for glutamate dehydrogenase
Authors: Dodd G. H. , Radda G. K.
Published: August 2015

1. The interaction of 1-anilinonaphthalene-8-sulphonate with ox liver glutamate dehydrogenase was examined. 2. The fluorescence of the dye is enhanced 100-fold on binding. 3. A further enhancement is observed when NADH and GTP are added to the enzyme. 4. By using this property of the dye to measure conformational equilibria in the enzyme the effects of coenzyme, inhibitors, enzyme concentration, ionic strength and pH on the allosteric transitions were studied. 5. GTP and NADH interact with the enzyme in a heterotropic manner. 6. The rate of the structural transition brought about by GTP and NADH is biphasic with half-lives of 34 and 200msec. 7. The relation of these observations to regulatory mechanisms is discussed.
Amino ketone synthesis in avian erythrocytes
Authors: Dale R. A.
Published: August 2015

1. The relative rates of synthesis of aminolaevulate and aminoacetone by particles prepared from avian erythrocytes were measured under various conditions. 2. The production of both amino ketones by fresh particles was about three times greater in anaemia caused by phenylhydrazine and acetylphenylhydrazine than in anaemia caused by removal of 20–30ml. of blood. 3. The synthesis of aminolaevulate by freeze-dried particles decreased more than that of aminoacetone in the absence of added pyridoxal phosphate, in the presence of cyanide and of tris buffer, and after preincubation of the erythrocyte particles. Other differences in the rates of synthesis of the two amino ketones were observed after (a) incubation of particles at different temperatures and (b) storage of homogenized freeze-dried particles at different pH values. 4. It is suggested that these differences in the production of the two amino ketones are due to the presence of two amino ketone synthetases or to two or more isoenzymes of aminolaevulate synthetase. 5. The metabolic significance of aminoacetone in erythrocytes is discussed.
Control of the citric acid cycle by glyoxylate. The mechanism of inhibition of oxoglutarate dehydrogenase, isocitrate dehydrogenase and aconitate hydratase
Authors: Adinolfi A. , Moratti R. , Olezza S. , Ruffo A.
Published: August 2015

1. The effects of glyoxylate on partially purified preparations of aconitate hydratase, isocitrate dehydrogenase and oxoglutarate dehydrogenase were compared with those of oxalomalate and hydroxyoxoglutarate (obtained by condensation of glyoxylate with oxaloacetate and pyruvate respectively). 2. Glyoxylate (1mm) did not affect aconitate hydratase and isocitrate dehydrogenase, whereas oxalomalate (1mm) inhibited the enzyme activities completely. 3. Glyoxylate (0·025mm) inhibited oxoglutarate dehydrogenase irreversibly, whereas the same concentrations of oxalomalate and hydroxyoxoglutarate were ineffective. This inhibitory effect was prevented if oxoglutarate, pyruvate or oxaloacetate was mixed with the enzyme before the glyoxylate. 4. Incubation of oxoglutarate dehydrogenase with radioactive glyoxylate produced radioactive carbon dioxide; radioactivity was also recovered in the portion of the enzyme identified with thiamin pyrophosphate. 5. The behaviour of glyoxylate in producing multiple inhibitions of the citric acid cycle, either by direct interaction with oxoglutarate dehydrogenase, or by means of its condensation compounds which inhibit aconitate hydratase and isocitrate dehydrogenase, is discussed.
A comparison of the effects of ultraviolet and ionizing radiations on trypsin activity and on its constituent amino acids
Authors: Burke Morris , Augenstein Leroy
Published: August 2015

Photons of 254nm. u.v. light, 60Co γ-rays and 1Mev electrons produce different patterns of destruction of individual amino acids in dried films of trypsin and in the corresponding amino acid mixture. For example, in the amino acid mixture u.v. light destroys tyrosine, tryptophan and cystine, whereas in trypsin only cystine is disrupted but with 10 times the initial yield. Further, in the amino acid mixture loss of half-cystine is a simple exponential function of dose, but in trypsin there appear to be two exponential components of the loss with yields that differ by a factor of 35. Both the γ-rays and electrons destroy half-cystine, tryptophan, histidine and methionine in the amino acid mixture with remarkably high yields, whereas in trypsin doses that destroy almost all of the enzymic activity produce no detectable destruction of amino acid residues. These marked differences between the two preparations show that the radiation-sensitivity of a given amino acid alone and in a protein is different, and suggests that in trypsin there is fairly extensive migration of energy, charge or both with localization of damage at specific sites determined by this enzyme's internal organization. All three types of radiation produce appreciable amounts of ‘damaged’ (not completely inactivated) molecules which are prevented from reassuming an active configuration by the addition of 5·5m-urea; thiol reagents have a similar effect after bombardment with u.v. light or electrons. The patterns of destruction produced by γ-rays and by electrons in both the amino acid mixture and in trypsin are different (some of the yields vary by a factor of 30). This result appears to be inconsistent with the popular belief that most of the energy absorbed from γ-rays is associated with very-high-energy electrons.
Incorporation of [14C]histidine into homocarnosine and carnosine of frog brain in vivo and in vitro
Authors: Yockey William C. , Marshall Finley D.
Published: August 2015

1. Homocarnosine, carnosine and histidine were determined in brain from several species and the results compared with values in the literature. 2. [14C]Homocarnosine and [14C]carnosine were isolated from frog brain after intracerebral injection of [14C]histidine in vivo. 3. Whole frog brain, incubated in vitro with l-[14C]histidine, formed labelled homocarnosine and carnosine. 4. A frog brain homogenate or supernatant fraction catalysed the incorporation of l-[14C]histidine into homocarnosine and carnosine. 5. The results indicate that brain tissue can synthesize homocarnosine and carnosine.
Spectrophotometric determination of pyridoxal and pyridoxal 5′-phosphate with 3-methyl-2-benzothiazolone hydrazone hydrochloride, and their selective assay
Authors: Soda Kenji , Yorifuji Takamitsu , Misono Haruo , Moriguchi Mitsuaki
Published: August 2015

A spectrophotometric method with 3-methyl-2-benzothiazolone hydrazone hydrochloride was developed for the determination of pyridoxal and pyridoxal 5′-phosphate, and for the selective determination of each in the presence of the other. Pyridoxal and pyridoxal 5′-phosphate react with the reagent to yield the azine derivatives, which give characteristic absorption spectra. The highest extinction values are obtained when pyridoxal and pyridoxal 5′-phosphate are incubated at pH values of about 3·4 and 8·0 respectively; their maxima are at 430nm. (∈ 2·74×104) and 380nm. (∈ 2·24×104) respectively. The azine of pyridoxal is only slightly soluble under the neutral and alkaline conditions, whereas that of pyridoxal 5′-phosphate is substantially insoluble in the acid pH range. This difference in solubility of the azines made possible the selective determination of pyridoxal and pyridoxal 5′-phosphate. α-Oxoglutarate and pyruvate are among the substances shown not to interfere with the assay of pyridoxal; their derivatives absorb appreciably only at wavelengths below 420nm. For the assay of pyridoxal 5′-phosphate in the presence of these compounds measurement at 390nm. is necessary.
The properties of a nuclear acidic protein fraction that binds [6,7−3H]oestradiol-17β
Authors: King R. J. B. , Gordon J. , Steggles A W
Published: August 2015

1. Additional evidence was obtained that the nuclear oestradiol-17β receptor is an acidic protein. Partial purification of the receptor protein was obtained by chromatography on hydroxyapatite and it contains protein-bound phosphate. 2. The nuclear ‘5s’ and cytoplasmic ‘9·5s’ and ‘5s’ receptors from uterus, dimethylbenzanthracene-induced mammary adenocarcinoma and kidney are precipitated together with bound oestradiol-17β by protamine sulphate. This common property suggests that the nuclear and cytoplasmic receptors are related to each other. 3. The properties of two acidic protein fractions from both liver and dimethylbenzanthracene-induced mammary adenocarcinoma are described. Fraction 1 contains two major components and fraction 2 contains one component, as judged from polyacrylamide-gel electrophoresis. Fraction 2 contains RNA and both fractions contain protein-bound phosphate. 4. These fractions form insoluble complexes with calf thymus histone, protamine sulphate and poly-l-lysine. The formation of these complexes is markedly affected by ionic strength and pH. Ionization of both the ∈-amino group of lysine and carboxyl group are involved. RNA and DNA do not appear to be involved. The interaction is not affected by EDTA or 1mm-Na+, -K+, -Ca2+, -Mg2+ or -Mn2+. Per unit weight, whole histone has 4–5 times as many binding sites for the acidic proteins as the latter have for the former. 5. No convincing evidence was obtained for DNA–acidic protein interaction, but, as judged from precipitation experiments, there was competition between DNA and acidic protein for histone. 6. Relatively large amounts of acidic protein partly relieved the histone inhibition of the template activity of DNA for Escherichia coli RNA polymerase (EC 2.7.7.6).
Effect of polyamines on the stability of brain-cortex ribosomes
Authors: Datta R. K. , Sen Suchandra , Ghosh J. J.
Published: August 2015

1. Ribosomes isolated from the cortex tissue of goat brain contain very small amounts of spermidine and spermine. Ribosomes isolated from spermidine-treated slices have a higher spermidine content. 2. The polyamines partially prevent the temperature-dependent breakdown of ribosomes into acid-soluble nucleotides. 3. The ‘melting’ temperature of ribosomes rises slightly when the ribosomes are heated slowly in the presence of polyamines. 4. The pH-dependent breakdown of ribosomes into protein, RNA and acid-soluble nucleotide is markedly decreased by polyamines present in media in which ribosomes are suspended. 5. The breakdown of ribosomes in the presence of high concentrations of salts and EDTA is partially checked by the concurrent presence of polyamines. 6. Spermidine and spermine make ribosomes less susceptible to enzymic digestion by crystalline trypsin and ribonuclease.
Interactions of cytochrome c and [14C]-carboxymethylated cytochrome c with monolayers of phosphatidylcholine, phosphatidic acid and cardiolipin
Authors: Quinn P. J. , Dawson R. M. C.
Published: August 2015

1. The interactions between cytochrome c (native and [14C]carboxymethylated) and monolayers of phosphatidylcholine, phosphatidic acid and cardiolipin at the air/water interface was investigated by measurements of surface radioactivity, pressure and potential. 2. On a subphase of 10mm-or m-sodium chloride, penetration of cytochrome c into egg phosphatidylcholine monolayers, as measured by an increase of surface pressure, and the number of molecules penetrating, as judged by surface radioactivity, were inversely proportional to the initial pressure of the monolayer and became zero at 20dynes/cm. The constant of proportionality was increased when the cytochrome c was carboxymethylated or decreased when the phospholipid was hydrogenated, but the cut-off point remained at 20dynes/cm. 3. Penetrated cytochrome c could be removed almost entirely by compression of the phosphatidylcholine monolayer above 20dynes/cm. 4. With phosphatidic acid and cardiolipin monolayers on 10mm-sodium chloride the binding of cytochrome c was much stronger and cytochrome c penetrated into films nearing the collapse pressure (>40dynes/cm.). The penetration was partly electrostatically facilitated, since it was decreased by carrying out the reaction on a subphase of m-sodium chloride, and the relationship between the surface pressure increment and the initial film pressure moved nearer to that observed with phosphatidylcholine. 5. Surface radioactivity determinations showed that [14C]carboxymethylated cytochrome c was still adsorbed on phosphatidic acid and cardiolipin monolayers after the cessation of penetration. This adsorption was primarily electrostatic in nature because it could be prevented and substantially reversed by adding m-sodium chloride to the subphase and there was no similar adsorption on phosphatidylcholine films. 6. The penetration into and adsorption on the three phospholipid monolayers was examined as a function of the pH of the subphase and compared with the state of ionization of both the phospholipid and the protein, and the area occupied by the latter at an air/water interface. 7. It is concluded that the binding of cytochrome c to phospholipids can only be partially understood by a consideration of the ionic interaction between the components and that subtle conformational changes in the protein must affect the magnitude and stability of the complex. 8. If cytochrome c is associated with a phospholipid in mitochondria then cardiolipin would fulfil the characteristics of the binding most adequately.
Purification and characterization of bovine aorta ribonucleases
Authors: Lewis R. A. , Gamble W.
Published: August 2015

1. Two ribonucleases (aorta ribonuclease I and aorta ribonuclease II) from bovine aorta were purified 4611-fold and 667-fold respectively. Ethanolic precipitation, acid extraction, isoionic precipitation at pH3·5 and Bio-Rex 70 column chromatography were the methods employed. 2. Aorta ribonuclease I exhibited no deoxyribonuclease or alkaline phosphatase activity. 3. Aorta ribonuclease I appeared to be homogeneous when subjected to discontinuous gel electrophoresis. 4. Aorta ribonuclease II exhibited the same properties as aorta ribonuclease previously isolated. 5. The activities of the aorta ribonucleases and pancreatic ribonuclease on homopolymers and dinucleoside phosphates were compared. 6. Aorta ribonuclease I exhibited optimum pH7·5 and, under the assay conditions used, optimum temperature 60°.
The initiation of haemoglobin synthesis in rabbit reticulocytes
Authors: Rahamimoff Hannah , Arnstein H. R. V.
Published: August 2015

1. The incorporation of labelled valine by rabbit reticulocytes into the N-terminal position of nascent haemoglobin was investigated by deaminating the nascent peptides with nitrous acid and isolating labelled α-hydroxyisovaleric acid and valine after acid hydrolysis. 2. The amount of radioactivity in α-hydroxyisovaleric acid relative to that in valine indicated the presence of 12·3% N-terminal valine having a free amino group. This high value suggests that most if not all nascent peptides contain valine in the N-terminal position. 3. Cell-free preparations containing reticulocyte ribosomes and pH5 enzymes incorporated α-hydroxy-[14C]isovaleryl-tRNA (where tRNA refers to transfer RNA), which was obtained by deamination of [14C]valyl-tRNA from yeast or liver with nitrous acid, into both soluble and nascent protein. 4. When the soluble protein was chromatographed on CM-cellulose, radioactivity was found to be associated with both the α-and β-globin chains. 5. The kinetics of hydrolysis of [14C]valine, was also investigated. Most of the material was hydrolysed rapidly at pH10, but a minor component that was relatively stable appeared to be present to the extent of about 10% of the total valyl-tRNA. Valine was, however, the only hydrolysis product detected by paper chromatography. 6. It is concluded that chain initiation in haemoglobin synthesis involves valine as the N-terminal amino acid and that the amino group of nascent protein is probably not substituted.
The intermediary role of a steroid 8,14-dien-3β-ol system in ergosterol biosynthesis
Authors: Akhtar M , Brooks W. A. , Watkinson I. A.
Published: August 2015

1. A mechanism for the removal of the 14α-methyl group in ergosterol biosynthesis that involves the intermediacy of an 8,14-diene system is outlined. 2. In accordance with the requirements of this scheme, it is shown that 5α-ergosta-8,14-dien-3β-ol is converted into ergosterol by Saccharomyces cerevisiae.
Studies of newly synthesized ribosomal ribonucleic acid of Escherichia coli
Authors: Fry Michael , Artman Michael
Published: August 2015

1. RNA synthesized by Escherichia coli during one-hundredth of the generation time contains two fractions distinguishable by hybridization with homologous DNA. One fraction, approximately 30% of the newly synthesized RNA, did not compete with ribosomal RNA, being apparently messenger RNA. The other fraction, approximately 70% of the newly made RNA, hybridized as ribosomal RNA. These values are comparable with previous estimates (McCarthy & Bolton, 1964; Pigott & Midgley, 1968). 2. Hybridization-competition experiments showed that the newly made RNA associated with 70s ribosomes and larger ribosome aggregates was a mixture of ribosomal RNA and messenger RNA, whereas that associated with nascent ribosomal subunits consisted exclusively of ribosomal RNA. This observation provides means by which newly synthesized ribosomal RNA can be isolated free from messenger RNA. 3. Newly made ribosomal RNA in nascent ribosomal subunits was sensitive to shear under conditions where ribosomal RNA in mature ribosomes was shear-resistant. Thus, when RNA was extracted from cells of E. coli disrupted by mechanical means, newly made ribosomal RNA appeared heterogeneous in size, sedimenting as a broad peak extending from 8s to 16s. 4. Newly synthesized ribosomal RNA in nascent ribosomal subunits was rapidly degraded in the presence of actinomycin D and during glucose starvation. 5. Newly synthesized ribosomal RNA stimulated amino acid incorporation in a system synthesizing protein in vitro to the same extent as the RNA which contained the messenger RNA fraction.
Goat immunoglobin G. Peptide chains and terminal residues
Authors: Givol D. , Hurwitz E.
Published: August 2015

Goat immunoglobulin G (IgG) was isolated and characterized. The molecular weights of the IgG and its heavy chains and light chains were found to be 144000, 53600 and 23000 respectively. The light chain corresponds to human L type as was shown by the absence of C-terminal S-carboxymethylcysteine and its high content of N-terminal pyrrolid-2-one-5-carboxylic acid (PCA). The major C-terminal residue of the light chain was serine and the major N-terminal dipeptide was PCA-Ala (0·6mole/mole). The major C-terminal residue of the heavy chain was glycine and the N-terminal sequence of the heavy chain is PCA-Val-Gln. This tripeptide was obtained in a 70% yield.
The effect of dietary and hormonal conditions on the activities of glycolytic enzymes in rat epididymal adipose tissue
Authors: Saggerson E. D. , Greenbaum A. L.
Published: August 2015

1. Measurements were made of the activities of nine glycolytic enzymes in epididymal adipose tissues obtained from rats that had undergone one of the following treatments: starvation; starvation followed by re-feeding with bread or high-fat diet; feeding with fat without preliminary starvation; alloxan-diabetes; alloxan-diabetes followed by insulin therapy. 2. In general, the activities of the glycolytic enzymes of adipose tissue, unlike those of liver, were not greatly affected by the above treatments. 3. The ‘key’ glycolytic enzymes, phosphofructokinase and pyruvate kinase, were generally no more adaptive in response to physiological factors than other glycolytic enzymes such as glucose phosphate isomerase, fructose diphosphate aldolase, triose phosphate isomerase, glycerol 3-phosphate dehydrogenase, phosphoglycerate kinase and lactate dehydrogenase. 4. Adiposetissue pyruvate kinase did not respond to feeding with fat in a manner similar to the liver enzyme. 5. Glyceraldehyde phosphate dehydrogenase had a behaviour pattern unlike the other eight glycolytic enzymes studied in that its activity was depressed by feeding with fat and was not restored to normal by re-feeding with a high-fat diet after starvation. These results are discussed in relation to the requirements of adipose tissue for glycerol phosphate in the esterification of fatty acids. 6. A statistical analysis of the results permitted the writing of linear equations describing the relationships between the activities of eight of the enzymes studied. 7. Evidence is presented for the existence of two constant-proportion groups amongst the enzymes studied, namely (i) glucose phosphate isomerase, phosphoglycerate kinase and lactate dehydrogenase, and (ii) triose phosphate isomerase, fructose diphosphate aldolase and pyruvate kinase. 8. Mechanisms for maintaining the observed relationships between the activities of the enzymes in the tissue are discussed.
A sodium ion concentration gradient formed during the absorption of glycine by mouse ascites-tumour cells
Authors: Eddy A A
Published: August 2015

1. To deplete them of ATP the tumour cells were starved at 37° in a Ringer solution containing 33m-equiv. of Na+/l., 131m-equiv. of Li+/l., 2mM-sodium cyanide and 0·1mm-ouabain. The cellular content of K+ was largely replaced by Li+, but cellular [Na+] remained near 33m-equiv./l. 2. The addition of 12mm-glycine to the system caused cellular [Na+] to increase, during the next 4min., by about 4m-equiv./l., so that it slightly exceeded extracellular [Na+]. This occurred in parallel with the absorption of glycine. 3. The cellular K+ content fell by an amount representing about 10% of the amount of Na+ absorbed. 4. The results provide a clear demonstration that the flow of glycine into the cells is linked to a parallel movement of Na+; K+ appears to play a facultative role in the carrier system, whereas Li+ is almost inert. 5. The effects produced by glycine were not reproduced by l-arabinose.
Cholesterol esterification in rabbit plasma
Authors: Stefanovich V.
Published: August 2015

1. When [4−14C]cholesterol, attached to β-globulin or dispersed with Tween 20, was incubated with fresh rabbit (New Zealand albino females) plasma, 30–47% esterification was observed. The optimum pH was 6·8. This esterification was accomplished by the transfer of fatty acids from the C-2 position of lecithin (phosphatidylcholine) to cholesterol. 2. There was no evidence that triglycerides or free fatty acids participated directly in this reaction. Lecithins with labelled palmitic acid, oleic acid and linoleic acid in the 2-position yielded 3·2, 4·8 and 6·8% of cholesteryl esters respectively. This pattern reflects that which is normally observed in the cholesteryl esters of rabbit plasma and supports the concept that plasma cholesteryl esters originate from the plasma. 3. Snake venom (containing phospholipase A), sulphoevernan [an α-(1→3,1→4)-sulphopolyglucan with 12% sulphur], thiol-blocking agents (p-chloromercuribenzoate and N-ethylmaleimide), or an atherogenic diet (stock diet supplemented with 1% cholesterol for 8 weeks) were all effective inhibitors of this cholesterol esterification.
The enzymic hydroxylation of protocollagen models
Authors: Kikuchi Y. , Fujimoto D. , Tamiya N.
Published: August 2015

1. Synthetic polymers of l-prolyl-l-prolylglycine of defined chain length, (Pro-Pro-Gly)n, were found to be substrates for the enzyme protocollagen–proline hydroxylase, with optimum chain length n=5. Boiling the polymer (Pro-Pro-Gly)15 increased its activity as a substrate but had no effect on (Pro-Pro-Gly)5. 2. Protection of both or one of the N- and C-terminal groups made (Pro-Pro-Gly)3 a better substrate, and collagenase digestion of hydroxylated tert.-pentyloxy-carbonyl-(Pro-Pro-Gly)3 benzyl ester indicated that the central prolyl residues were the major points of hydroxylation. 3. The results suggest that the long-chain peptides are optimum substrates but that a triple-stranded structure is inhibitory for hydroxylation.
Purification and properties of 6-phosphogluconate dehydrogenase from sheep liver
Authors: Villet R. H. , Dalziel K.
Published: August 2015

A method is described for the isolation of 6-phosphogluconate dehydrogenase from sheep liver. The product appears to be homogeneous in polyacrylamide-gel electrophoresis and in sedimentation-velocity and sedimentation-equilibrium studies in the ultracentrifuge. The molecular weight is estimated as 129000 from equilibrium sedimentation.
Factors affecting the synthesis of ampicillin and hydroxypenicillins by the cell-bound penicillin acylase of Escherichia coli
Authors: Cole M.
Published: August 2015

1. The effect of pH, temperature, reactant concentration and reaction time has been investigated for the synthesis of benzylpenicillin, dl-α-hydroxybenzylpenicillin and d-α-aminobenzylpenicillin from 6-aminopenicillanic acid by the penicillin acylase of Escherichia coli. 2. Synthesis of penicillins from carboxylic acids proceeds most rapidly at pH5; with amides the optimum pH is higher (6–7) but the reverse reaction rapidly sets in. This can be counteracted by lowering the pH or adding more amide. Optimum temperatures are 35–40°. 3. Most rapid synthesis of penicillin was obtained with the N-acylglycine and methyl ester derivatives of carboxylic acids. Increasing the amide/6-APA ratio above 1:1 raised the rate of synthesis of penicillins. 4. Preferential synthesis of d-α-hydroxybenzylpenicillin takes place in a reaction mixture containing dl-mandelic acid. 5. From d- and l-mandelamide, d- and l-α-hydroxybenzylpenicillins were prepared, the former being more bioactive than the latter. p-Hydroxy- and 3,4-dihydroxybenzylpenicillins were also prepared, the latter being more active against some Gram-negative bacteria than benzylpenicillin.
N-Terminal sequences of α-crystallin
Authors: Corran P. H. , Waley S. G.
Published: August 2015

The amino acid sequences at the N-terminal ends of the chains of the lens protein, α-crystallin, were studied. Both the main kinds of chain in bovine α-crystallin (A chains and B chains) have an N-terminal methionine residue, and the amino group is acetylated. Selective purification of the peptides in a tryptic digest of bovine α-crystallin gave a preparation consisting largely of the N-terminal peptide from the A chains, and the sequence of this peptide was elucidated. Subsequently, the N-terminal peptides were prepared from separated A and B chains. The proposed sequences are: A chain, acetyl-Met-Asp-Ile-Ala-Ile-Gln-His-Pro-Trp-Phe-Lys; B chain, acetyl-Met-Asp-Ile-Ala-Ile-His-(Pro,Trp)-Ile-Arg. The similarity between the sequences supports the hypothesis that the A and B chains are derived evolutionarily from a common precursor.
Attempted isolation of a heparin proteoglycan from bovine liver capsule
Authors: Lindahl U.
Published: August 2015

(1) Polysaccharides were isolated from bovine liver capsule by extraction with 2m-potassium chloride followed by precipitation from 0.8m-potassium chloride with cetylpyridinium chloride. Chondroitin sulphate was eliminated by digestion with hyaluronidase. The yield of heparin was approx. 40% of that obtained after extraction of the papain-digested tissue. (2) The macromolecular properties of the hyaluronidase-digested polysaccharide were studied by gel chromatography on Sephadex G-200 of the intact, as well as of the alkali-degraded, material. The results suggested the presence of single heparin chains in addition to a dermatan sulphate proteoglycan. (3) A purified heparin preparation was analysed for amino acids and neutral sugars. Xylose, galactose and serine were found in amounts corresponding to 0.1, 0.2, and 0.4 residue/polysaccharide chain (mol.wt. 7400), respectively. It is suggested that the isolated material had been degraded by a polysaccharidase with endo-enzyme properties.
The enzymic composition of the isolated cell wall and plasma membrane of baker's yeast
Authors: Nurminen T. , Oura E. , Suomalainen H.
Published: August 2015

A study was made of the enzyme content of the isolated cell walls and of a plasma-membrane preparation obtained by centrifugation after enzymic digestion of the cell walls of baker's yeast. The isolated cell walls showed no hexokinase, alkaline phosphatase, esterase or NADH oxidase activity. It was concluded that these enzymes exist only in the interior of the cell. Further, only a negligible activity of deamidase was detectable in the cell walls. Noticeable amounts of saccharase, phosphatases hydrolysing p-nitrophenyl phosphate, ATP, ADP, thiamin pyrophosphate and PPi, with optimum activity at pH3–4, and an activity of Mg2+-dependent adenosine triphosphatase at neutral pH, were found in the isolated cell walls. During enzymic digestion, the other activities appearing in the cell walls were mostly released into the medium, but the bulk of the Mg2+-dependent adenosine triphosphatase remained in the plasma-membrane preparation. Accordingly, it may be assumed that the enzymes released into the medium during digestion are located in the cell wall outside the plasma membrane, whereas the Mg2+-dependent adenosine triphosphatase is an enzyme of the plasma membrane. This enzyme differs from the phosphatases with pH optima in the range pH3–4 with regard to location, pH optimum, substrate specificity and different requirement of activators.
A novel sequence for phytoene dehydrogenation in Rhodospirillum rubrum
Authors: Davies B. H.
Published: August 2015

Differences between the absorption spectra of ζ-carotene (7,8,7′,8′-tetrahydrolycopene) and the corresponding conjugated heptaene from diphenylamine-inhibited cultures of Rhodospirillum rubrum have been rationalized by the identification of the latter compound as the unsymmetrical isomer, 7,8,11,12-tetrahydrolycopene. The structures of the other conjugated polyene hydrocarbons, phytoene, phytofluene and neurosporene, have been confirmed and a novel pathway for the dehydrogenation of phytoene to lycopene in these bacteria is described.
The distributions of some granule-associated enzymes in guinea-pig polymorphonuclear leucocytes
Authors: Michell Robert H. , Karnovsky Morris J. , Karnovsky Manfred L.
Published: August 2015

1. Homogenates of guinea-pig polymorphonuclear leucocytes were separated by differential centrifugation into six particulate fractions and a soluble fraction. 2. The distributions in these fractions of protein, DNA, succinate dehydrogenase, β-glucuronidase, peroxidase, alkaline phosphatase, acid phosphatase (against p-nitrophenyl phosphate and β-glycerophosphate), cathepsin, and catalase were compared. 3. Almost all of the DNA sedimented in the first two pellets, indicating that the nuclei were relatively intact. 4. The four hydrolases and peroxidase showed different distribution patterns, although these activities were previously reported to be localized mainly in the single ‘granule’ fraction isolated from leucocytes. 5. The particles containing peroxidase, acid phosphatase and alkaline phosphatase all exhibited latency. Maximum activity for each enzyme was obtained at roughly similar concentrations of Triton X-100. 6. The acid phosphatase of these cells was distributed between two populations of particles that differed in both sedimentation characteristics and density. The acid phosphatase(s) of the two populations showed slightly different substrate specificities. This bimodal distribution was not an artifact of the procedure used to elicit the cells. 7. Catalase was recovered almost entirely in the soluble fraction and showed no latency in freshly prepared homogenates. No urate oxidase was detected. 8. We conclude that the ‘granule’ fraction of the polymorphonuclear leucocyte, as isolated by previous workers, contains at least three, probably more, populations of particles with different enzyme contents, and that these cells probably do not contain peroxisomes.
Sequence studies of the Fd section of the heavy chain of rabbit immunoglobulin G
Authors: Fruchter R. G. , Jackson S. A. , Mole L. E. , Porter R. R.
Published: August 2015

A partial amino acid sequence was given by Cebra, Steiner & Porter (1968b) of the N-terminal half of the heavy chain of rabbit immunoglobulin G. This was extended and in part corrected to give a continuous sequence of 136 residues, which together with other work accounts for three-quarters of the total sequence. Evidence is given suggesting that there is a limited region of 10–15 residues that are exceptionally variable in the heavy chains from pooled rabbit immunoglobulin G.
Changes in proportion of thiol to disulphide in acid-soluble nuclear proteins of Echinus during the first cell cycle
Authors: Ord Margery G. , Stocken L. A.
Published: August 2015

1. DNA synthesis in Echinus esculentus eggs kept at 10°C takes place just after fusion, 0.75–1.5h after fertilization, and at telophase at about 2.67–3.33h after fertilization. 2. An increase in the thiol/thiol+disulphide ratio in acid extracts from washed nuclear fractions of the eggs is found at fusion, at early stages of mitosis and at telophase. When DNA is being synthesized, the relative amount of thiol in the extracts increases. 3. There are at least five thiol-containing histones in the acid extract together with a diffusible thiol peptide containing methyl-lysine and 3-methylhistidine and a thiol-containing acidic protein.
Preparation, purification and analyses of thirteen alkali-stable dinucleotides from ribonucleic acid
Authors: Trim A. R. , Parker Janet E.
Published: August 2015

Of the 16 alkali-stable dinucleotides known to be obtained by hydrolysis of commercial yeast RNA with alkali, 13 were prepared in quantities of the order of 10mg or more. The samples, with only one exception, contain at least 90% of dinucleotide, and spectroscopic constants and nucleotide-sequence determinations, although not conclusive, indicate a high degree of purity of these products. The small dinucleotide fraction in 150g of RNA hydrolysed with alkali (1–2% of the total nucleotides) was separated from the mononucleotides by stepwise ion-exchange chromatography on DEAE-cellulose columns and resolved into seven fractions containing from one to four different dinucleotides by electrophoresis on paper at pH3.0. These fractions were resolved into their constituent dinucleotides by chromatography in ammonium sulphate. Contamination of the products by impurities from the paper was minimized by washing it before using it for chromatography or electrophoresis and, by using a thick grade of paper (Whatman no. 17), it was possible to handle and purify relatively large quantities of nucleotides.
Synthesis of cell constituents by methane-grown Methylococcus capsulatus and Methanomonas methanooxidans
Authors: Lawrence A. J. , Kemp M. B. , Quayle J. R.
Published: August 2015

1. A study was made of the incorporation of carbon from [14C]methanol by cultures of Methylococcus capsulatus and Methanomonas methanooxidans growing on methane. 2. The distribution of radioactivity within the non-volatile constituents of the ethanol-soluble fractions of the cells, after incubation with labelled substrate for periods of up to 3min, was analysed by chromatography and radioautography. 3. Over 80% of the radioactivity fixed by Methylococcus capsulatus at 30°C at the earliest times of sampling appeared in phosphorylated compounds, of which glucose phosphate constituted 60%. 4. Most of the radioactivity fixed by Methanomonas methanooxidans at 30°C at the earliest times of sampling appeared in serine, malate, aspartate and an unknown compound(s) tentatively suggested to be folate derivative(s). At 16°C, [14C]methanol was fixed predominantly into serine and the unknown compound(s). 5. Extracts of Methylococcus capsulatus contain an enzyme system that catalyses the condensation of formaldehyde and ribose 5-phosphate to give a mixture consisting mainly of fructose phosphate and allulose phosphate. No similar activity was detected in extracts of Methanomonas methanooxidans. A convenient method was developed for assay of this enzyme system. 6. The enzyme system catalysing the condensation of formaldehyde with ribose 5-phosphate is particle-bound in both Methylococcus capsulatus and Pseudomonas methanica and is unstable in the absence of Mg2+. 7. Extracts of Methanomonas methanooxidans contain high activities of d-glycerate–NAD oxidoreductase, whereas extracts of Methylococcus capsulatus and Pseudomonas methanica contain negligible activities of this enzyme. 8. These results indicate that during growth of Methylococcus capsulatus on methane, as with Pseudomonas methanica, cell constituents are made by the ribose phosphate cycle of formaldehyde fixation. This contrasts with Methanomonas methanooxidans, whose assimilation pathway resembles in some features that of Pseudomonas AM1 growing on methanol.