bluuebunny/crossref_metadata_2025 huggingface dataset:
Construction of spirocycles containing highly substituted pyrroli-dine and 1-indanone motifs with spiro quaternary stereogenic centers via 1,3-dipolar cycloaddition of 2-alkylidene-1-indanone and azomethine ylides promoted by simple imidazolium salts
Authors: Hu Wei-Qiang , Cui Yan-Su , Wu Zhi-Jun , Zhang Chuan-Bao , Dou Pei-Hao , Niu Song-Yang , Fu Ji-Ya , Liu Yong
Published: August 2015

The 1,3-dipolar cycloaddition of 2-alkylidene-1-indanone with azomethine ylides has been successfully developed promoted by simple imidazolium salts to construct a variety of spirocycles, containing highly substituted pyrrolidines, in excellent yields (up to 99%).
Ribonucleic acid synthesis by Escherichia coli C3000/L after infection by the ribonucleic acid coliphage ZIK/1, and properties of coliphage-ZIK/1 ribonucleic acid
Authors: Bishop DHL
Published: August 2015

1. A method is described for the preparation and purification of the RNA from the RNA coliphage ZIK/1. 2. Some of the physical characteristics and infective properties of coliphage-ZIK/1 RNA were examined. 3. A method is also described for examining the type and quantity of RNA synthesized after bacteriophage infection. 4. Ribosome synthesis was decreased 15min. after bacteriophage adsorption, bacteriophage RNA was synthesized from 15min. to 120min. after adsorption and intracellular bacteriophages appeared 40min. after adsorption. Cell lysis commenced 60min. after adsorption, and was half complete 20min. later and 90-95% complete 120min. after adsorption. 5. Cell division continued until 40min. after bacteriophage adsorption. 6. Bacterial ribosomes were conserved during the infective process. 7. Intracellular bacteriophage RNA has sedimentation coefficient 28s but after cell lysis it has sedimentation coefficient 10-5s.
Purification, properties and comparative specificities of the enzyme prolyl-transfer ribonucleic acid synthetase from Phaseolus aureus and Polygonatum multiflorum
Authors: Peterson PJ , Fowden L
Published: August 2015

1. A prolyl-s-RNA synthetase (prolyl-transfer RNA synthetase) has been purified about 250-fold from seed of Phaseolus aureus (mung bean), a species not producing azetidine-2-carboxylic acid, and more than 10-fold from rhizome apices of Polygonatum multiflorum, a liliaceous species containing azetidine-2-carboxylic acid. The latter enzyme was unstable during ammonium sulphate fractionation. 2. The enzymes exhibited different substrate specificities towards the analogue. That from Phaseolus, when assayed by the ATP-PP(i) exchange, showed azetidine-2-carboxylic acid activation at about one-third the rate with proline. Both labelled imino acids gave rise to a labelled aminoacyl-s-RNA. The enzyme from Polygonatum, however, activated only proline. 3. The enzyme from Polygonatum also formed a labelled prolyl-s-RNA with Phaseolus s-RNA but at a lower rate than when the Phaseolus enzyme was used. No reaction occurred when the Phaseolus enzyme was coupled with Polygonatum s-RNA, and only a very slight one was observed when both enzyme and s-RNA came from Polygonatum. 4. Protein preparations from seeds of Pisum sativum, another species not producing azetidine-2-carboxylic acid, also activated the analogue in addition to proline, whereas those from rhizome and seeds of Convallaria, the species from which the analogue was originally isolated, failed to activate it. However, a liliaceous species not producing the analogue, Asparagus officinalis, activated it. 5. Of the other proline analogues investigated, only 3,4-dehydro-dl-proline and l-thiazolidine-4-carboxylic acid were active with the enzyme preparation from Phaseolus. 6. pH optima of 7.9 and 8.4 were established for the enzymes from Phaseolus and Polygonatum respectively. 7. The Phaseolus enzyme was specific for ATP and PP(i). Mn(2+) partially replaced the requirement for Mg(2+) as cofactor. Preincubation with p-chloromercuribenzoate at a concentration of 0.5mm or higher produced over 99% inhibition of the Phaseolus enzyme. One-half the enzymic activity was destroyed by preheating for 5min. at 62 degrees in tris-hydrochloric acid buffer, pH7.9. 8. All experimental evidence supports the hypothesis that azetidine-2-carboxylic acid and proline are activated by the same enzyme in Phaseolus preparations, whereas the analogue was inactive in all Polygonatum preparations. The possible nature of this different substrate behaviour is discussed.
‘Phosphatido-peptide’-like complexes formed by the interaction of calcium triphosphoinositide with protein
Authors: Dawson RMC
Published: August 2015

1. The sodium salt of triphosphoinositide partitions in the upper polar phase in a biphasic chloroform-methanol-water system similar to that of Folch et al. (1957). 2. On the addition of 2mug.atoms of Ca(2+) or Mg(2+) per mumole of triphosphoinositide the phospholipid passes entirely into the lower non-polar phase as the dicalcium or dimagnesium salt. 3. When serum albumin is included in the biphasic system, some of the dicalcium (dimagnesium) triphosphoinositide becomes attached to the protein material at the interface. 4. The affinity of Ca(2+) for triphosphoinositide is 2-2.5 times as great as that of Mg(2+) and the salt is not dissociated appreciably by equimolar amounts of EDTA or cyclohexane-1,2-diaminetetra-acetate. 5. When dicalcium triphosphoinositide is mixed with serum albumin a complex is formed which is insoluble in chloroform-methanol (2:1, v/v) but which dissolves completely when 0.25% (v/v) of concentrated hydrochloric acid is added. 6. On homogenizing a chloroform-methanol solution of dicalcium triphosphoinositide with guinea-pig liver the phospholipid becomes quantitatively attached to the insoluble residue, but it can be completely extracted from this with acidified chloroform-methanol. 7. The relevance of these observations to the significance of the phosphatido-peptide-complexes extracted from brain is discussed.
An investigation of the decolorization of caeruloplasmin by acid
Authors: Curzon G
Published: August 2015

1. The acid decolorization of caeruloplasmin was studied at various temperatures and pH values. 2. Two decolorization reactions may be distinguished: (i) an irreversible reaction with the thermodynamic characteristics of a protein denaturation; (ii) the attainment of an equilibrium between blue and colourless forms of caeruloplasmin with apparent pK 3.7 at 25 degrees . 3. The low temperature-dependence of the equilibrium suggests that it does not involve a gross denaturative change. 4. The reversible decolorization occurred both aerobically and anaerobically, indicating that the change does not involve dissociation of a copper-oxygen complex. 5. Spectral changes during the decolorization are described. 6. The changes occurring during acid decolorization are discussed in relation to a formal model of the gross structure of caeruloplasmin.
The integrity of deoxyribonucleic acid extracted from Escherichia coli 15T- after thymine-less death
Authors: Smith BJ , Burton K
Published: August 2015

1. The integrity of DNA extracted from Escherichia coli strain 15T(-) after thymine-less death was examined by studying the effects of treatment with aqueous alkali on the solubility in dilute acids and by viscosity and ultracentrifugal measurements, some of which were designed to detect single-strand breaks or inter-strand cross-links. None of the results showed that there was any modification or damage associated with thymine-less death.
Linkage of carbohydrate to hydroxyamino acids in mucopolysaccharides and mucoproteins
Authors: Adams JB
Published: August 2015

1. Glycosidic linkage of carbohydrate to the primary hydroxyl groups of threonine and serine has been established in human blood-group A and Le(a) substances, bovine submaxillary-gland mucin and human pseudomyxomatous mucin. 2. Treatment of these substances in 0.09n-lithium hydroxide at 100 degrees for 1hr. led to beta-elimination at these glycosidic linkages with the resultant formation of alpha-oxobutyric acid and glycine from threonine linkages, and pyruvic acid from serine linkages. Though most of the threonine was destroyed in every case, about one-third to one-half of the serine residues resisted alkaline cleavage. Such results, indicative of the presence of unbound serine residues, allow, in submaxillary mucin, for a close correlation between the remaining serine, threonine, glutamic acid and aspartic acid and the available sialyl-(2-->6)-N-acetylgalactosamine prosthetic groups. 3. The stoichiometry of the beta-eliminations has been demonstrated for pseudomyxomatous mucin. The alpha-oxo acids were separated and determined as their quinoxalinol derivatives by thin-layer chromatography on silica gel. Reaction at the threonine centres favoured alpha-oxobutyric acid formation (70%, via the intermediary dehydropeptide) over the alternative pathway to glycine (30%). 4. 100% of the hexosamine was destroyed in submaxillary-gland mucin, 85% in pseudomyxomatous mucin and about 60% in the blood-group substances. In the latter cases, the glucosamine/galactosamine ratio was increased from about 4:1 to 8-10:1, suggesting a preferential destruction of galactosamine. Evidence was obtained, however, for a further destruction of hexosamine, in addition to that which could be theoretically attached to peptide at possible known binding sites. 5. The major part of the alkali-resistant hexosamine in the blood-group substances was non-diffusible and was accompanied by the constituent carbohydrates in similar molar proportions to the native materials.
Interaction of N-alkyl-N-nitrosourethanes with thiols
Authors: Schoental R , Rive DJ
Published: August 2015

1. The interaction at room temperature of thiols (cysteine and certain of its derivatives, and glutathione) with N-alkyl-N-nitrosourethanes and with diazomethane gave complicated mixtures of products. 2. S-Methylcysteine and S-ethoxycarbonylcysteine, the main products of the reaction between cysteine and N-methyl-N-nitrosourethane, were isolated and unequivocally identified. Paper-chromatographic and other evidence was used for the identification of several other components of the mixtures of products obtained. 3. S-Methyl derivatives and their methyl esters were the common products formed from the thiol compounds with both N-methyl-N-nitrosourethane and with diazomethane. 4. The esters were unstable and hydrolysed readily. 5. S-Ethoxycarbonyl derivatives, the primary products of the reaction of the thiols with N-alkyl-N-nitrosourethanes, isomerized to the respective N-ethoxycarbonyl derivatives when the pH increased above 7.0; the migration of the ethoxycarbonyl group from S to N was particularly easy with cysteine, probably owing to the spatial proximity of the amino group. 6. It is suggested that the non-enzymic reactions in vitro of thiols with both N-methyl-N-nitrosourethane and diazomethane may represent models for events in vivo and might help in the studies of the carcinogenic process.
Adenosine-triphosphatase activity and nicotinamide nucleotide coenzymes in the parotid gland of the young lamb and adult sheep
Authors: Filsell OH , Jarrett IG
Published: August 2015

1. The activity of a Mg(2+)-dependent Na(+)-plus-K(+)-activated adenosine triphosphatase and the concentrations of nicotinamide nucleotide coenzymes have been measured in the immature parotid glands of young lambs and in the actively secreting glands of adult sheep. 2. The activity of the adenosine triphosphatase increased during development and attained relatively high levels in the mature secreting gland. 3. A high ([NAD]+[NADH(2)])/([NADP]+[NADPH(2)]) ratio (approx. 10:1) was observed in the parotid glands of lambs and sheep. 4. The high concentrations of NAD and the very low concentrations of NADPH(2) have been discussed in relation to metabolic activity, the activity of the Na(+)-plus-K(+)-activated adenosine triphosphatase and the secretion of saliva by the parotid gland.
Observations on the structure of bacilysin
Authors: Rogers HJ , Lomakina N , Abraham EP
Published: August 2015

1. Elementary analysis and other properties of a highly purified preparation of bacilysin indicated that a possible molecular formula for the substance is C(12)H(18)N(2)O(5). The results of electrometric titration were consistent with the hypothesis that the substance was a peptide containing one free alpha-amino group and one free carboxyl group. 2. Hydrolysis of bacilysin with 6n-hydrochloric acid at 105 degrees yielded l-alanine and l-tyrosine, but the ultraviolet spectrum of the substance showed that no tyrosine residue was present in the molecule and a nuclear-magnetic-resonance spectrum indicated that olefinic and aromatic protons were absent. The dinitrophenyl (DNP) derivative of bacilysin yielded DNP-alanine on acid hydrolysis. 3. Bacilysin was hydrolysed by leucine aminopeptidase (EC 3.4.1.1) and by Pronase to give alanine and an uncharacterized amino acid. Its infrared spectrum was consistent with the presence of a peptide grouping in the molecule. 4. The optical rotatory dispersion of bacilysin and its reaction with thiosemicarbazide indicated that the substance contained an aldehyde or ketone group. Its behaviour on catalytic reduction and its reaction with sodium thiosulphate and with certain thiols suggested that an epoxide group was present. 5. A possible type of structure for bacilysin is considered in the light of its known properties.
Studies on the properties of cow's-milk tributyrinases and their interaction with milk proteins
Authors: Downey WK , Andrews P
Published: August 2015

1. The tributyrinases in milk are mainly associated with casein micelles. Dilution or addition of sodium chloride increases the enzyme activity, probably by dissociating the micelle-tributyrinase complexes. 2. Tributyrinase activities of milks activated by dilution and sodium chloride addition were in the range 0.2-1.7muequiv. of acid liberated/ml. of milk/min. from tributyrin emulsion at pH8.5 and 25 degrees . The enzymes have a bivalent-cation requirement for full activity and are rather unstable when separated from casein. 3. Ultracentrifugation of skim milks containing sodium chloride (0.75m) gave preparations low in casein but containing about 70% of the milk tributyrinases. The tributyrinases in such preparations appear to be bound in complexes of molecular weight about 350000. Dilution may result in dissociation to give the free enzymes. 4. Pancreatic lipase also formed complexes with casein micelles, but wheat-germ esterase, xanthine oxidase, milk alkaline phosphatase and other enzymes did not.
Metabolism of the herbicide 2,6-dichlorobenzonitrile in rabbits and rats
Authors: Wit JG , Van Genderen H
Published: August 2015

1. The metabolism of 2,6-dichlorobenzonitrile was studied in rabbits and rats. Oral administration caused an increased urinary excretion of glucuronides and ethereal sulphates. There was also an indication of mercapturic acid formation. 2,6-Dichloro-3-hydroxybenzonitrile and its 4-hydroxy analogue were identified as metabolites in the urine. A small amount of the unchanged substance was recovered from the faeces. 2. By using 2,6-dichlorobenzo[(14)C]nitrile the phenolic metabolites were determined quantitatively and some other possible metabolic routes were excluded. 3. Incubation of 2,6-dichlorobenzonitrile with enzyme preparations (papain and high-speed supernatant of rat-liver homogenate plus glutathione) gave no indications for a reaction with thiol compounds.
Purification and properties of two glyoxylate reductases from a species of Pseudomonas
Authors: Cartwright LN , Hullin RP
Published: August 2015

1. Two enzymes that catalyse the reduction of glyoxylate to glycollate have been separated and purified from a species of Pseudomonas. Their molecular weights were estimated as 180000. 2. Reduced nicotinamide nucleotides act as the hydrogen donators for the enzymes. The NADH-linked enzyme is entirely specific for its coenzyme but the NADPH-linked reductase shows some affinity towards NADH. 3. Both enzymes convert hydroxypyruvate into glycerate. 4. The glyoxylate reductases show maximal activity at pH6.0-6.8, are inhibited by keto acids and are strongly dependent on free thiol groups for activity. 5. The Michaelis constants for glyoxylate and hydroxypyruvate were found to be of a high order. 6. The reversibility of the reaction has been demonstrated for both glyoxylate reductases and the equilibrium constants were determined. 7. The reduction of glyoxylate and hydroxypyruvate is not stimulated by anions.
Studies in lipogenesis in vivo. Fatty acid and cholesterol synthesis during starvation and re-feeding
Authors: Jansen GR , Zanetti ME , Hutchison CF
Published: August 2015

1. Lipogenesis in vivo has been studied in mice given a 250mg. meal of [U-(14)C]glucose (2.5muc) or given an intraperitoneal injection of 25mug. of [U-(14)C]glucose (2.0muc). 2. The ability to convert a [U-(14)C]glucose meal into fatty acid was not significantly depressed by 6-7hr. of starvation. In contrast, incorporation of (14)C into fatty acid in the liver after the intraperitoneal dose of [(14)C]glucose was depressed by 80% and by more than 90% by 1 and 2hr. of starvation respectively. Carcass fatty acid synthesis from the [U-(14)C]glucose meal was not depressed by 12hr. of starvation, whereas from the tracer dose of [U-(14)C]glucose the depression in incorporation was 80% after 6hr. of starvation. 3. Re-feeding for 3 days, after 3 days' starvation, raised fatty acid synthesis and cholesterol synthesis in the liver fivefold and tenfold respectively above the levels in non-starved control mice. These increases were associated with an increased amount of both fatty acid and cholesterol in the liver. 4. After 18hr. of starvation incorporation of a [U-(14)C]glucose meal into carcass and liver glycogen were both increased threefold.
Intrachain disulphide bridges in immunoglobulin G heavy chains. The Fc fragment
Authors: Frangione B. , Milstein C. , Franklin Edward C.
Published: August 2015

The disulphide bridges of the Fc fragment (C-terminal half of the heavy chain) have been studied in several human immunoglobulins, containing heavy chains of different antigenic types (γ1, γ2, γ3 and γ4), and in heavy-chain-disease proteins. Two intrachain disulphide bridges were found to be present. The sequences appear to be identical in the Fc fragments of two types of chain studied (γ1 and γ3), and very similar to corresponding sequences of the Fc fragment in rabbit. These results suggest that the C-terminal half of the heavy chains is covalently folded (in a similar fashion to the light chains) with a C-terminal loop and an N-terminal loop. The similarity is emphasized by comparison of the sequence and location of the disulphide-bridged peptides of the C-terminal loop of heavy and light chains. The N-terminal loop, on the other hand, appears to be very different in Fc fragments and light chains. The C-terminal loop is the only one present in the F′c fragment.
Preparation and some properties of rat skeletal-muscle polyribosomes
Authors: Chen S. C. , Young V. R.
Published: August 2015

1. A method is described for the sucrose-gradient sedimentation analysis of ribosomes in a post-mitochondrial supernatant of rat skeletal muscle. 2. An essential feature of the method involves the use of buffer of ionic strength 0·3 for homogenization of the muscle tissue. 3. Polyribosomes can be prepared by precipitation from post-mitochondrial supernatant of skeletal muscle by adjustment of the potassium chloride content of the medium. These polyribosomes stimulate cell-free amino acid incorporation in vitro in an energy-dependent system. 4. Ribosome aggregates of uniform size distribution can be obtained by adjustment of the ionic strength of the post-mitochondrial supernatant, followed by differential sucrose-gradient centrifugation. 5. In vivo, rat skeletal-muscle polyribosomes became labelled by 14C-labelled amino acid within 15min., and radioactivity was associated with the light ribosome species within 45min. 6. Electron microscopy of the polyribosomes revealed aggregations containing more than 40 single ribosomes.
The purification and properties of two staphylolytic enzymes from Streptomyces griseus
Authors: Ward J. B. , Perkins H R
Published: August 2015

1. Two staphylolytic enzymes have been purified from cultures of a soil isolate of Streptomyces griseus. 2. The purified enzymes were shown to be basic proteins of low molecular weight. Each enzyme released N-acetylmuramic acid reducing groups from the cell walls of Staphylococcus aureus. 3. The enzymes lysed whole staphylococci best at higher pH values and lower ionic strengths than when the substrate was isolated cell walls or purified mucopeptide. 4. Added teichoic acid did not inhibit the enzymes, but it formed an ethanol-precipitable complex with them. 5. The possibility that teichoic acid on the surface of whole cells prevents the access of the enzymes to their mucopeptide substrate is discussed.
Exchangeability of radioactive acetylcholine with the bound acetylcholine of synaptosomes and synaptic vesicles
Authors: Marchbanks R. M.
Published: August 2015

1. The exchangeability with added radioactive acetylcholine of the acetylcholine in isolated presynaptic nerve terminals (synaptosomes) and isolated synaptic vesicles was studied by a Sephadex-column method. 2. A substantial proportion of the synaptosomal acetylcholine is exchangeable with added radioactive acetylcholine. It is liberated by hypo-osmotic shock and ultrasonic treatment, and behaves as though it occupies the cytoplasmic compartment of synaptosomes. 3. Methods of isolating vesicles from hypo-osmotically ruptured synaptosomes in optimum yield are discussed. 4. The acetylcholine of synaptic vesicles isolated on a sucrose density gradient is released by hypo-osmotic conditions, suggesting that it is enclosed by a semi-permeable membrane; however, it is not easily released by ultrasonic treatment. 5. Added radioactive acetylcholine does not exchange with vesicular acetylcholine under a variety of different conditions. These include addition of ATP and Mg2+, and pre-loading of the synaptosome with radioactive acetylcholine before hypo-osmotic rupture. This failure to exchange is discussed in terms of the possible storage mechanism of vesicular acetylcholine.
Carotenoids in floral parts of a narcissus, a daffodil and a tulip
Authors: Valadon L. R. G. , Mummery Rosemary S.
Published: August 2015

1. The qualitative and quantitative distribution of carotenoids of the floral parts of three monocotyledons, the narcissus Scarlet Elegance, the daffodil King Alfred and the tulip Golden Harvest, were studied. β-Carotene, lutein or epoxy-β-carotenes were usually the main pigments, depending on the floral part and on the flower. When β-carotene was the major pigment there were only small amounts of, or sometimes no, epoxycarotenes. 2. Anthers, stigmas and styles of the three flowers did not possess any specific carotenoids but in some cases contained appreciable amounts of epoxycarotenoids. The possibility that these take part in reproduction is discussed. 3. The generalization that yellow flowers contained large amounts of xanthophylls and only traces of carotenes, whereas deep-orange flowers seemed to be characterized by the presence of large amounts of one carotene, was not always the correct one. It is suggested that the floral parts are yellow or orange depending on what carotenoids are present, which is the major one and the amount of total carotenoids, and also on the presence of other non-carotenoid pigments. 4. Two new probable isomers of 5,6:5′,6′-diepoxy-β-carotene were isolated and found together in various floral parts of the tulip Golden Harvest.
The isolation of the native hormone-binding proteins from bovine pituitary posterior lobes. Crystallization of neurophysin-I and -II as complexes with [8-arginine]-vasopressin
Authors: Hollenberg M D , Hope D B
Published: August 2015

1. The native hormone-binding proteins, neurophysin-I and -II, have been isolated from acetone-desiccated bovine pituitary posterior lobes. 2. Neurophysin-I and -II are present in approximately equal quantities in the tissue and are localized in the neurosecretory granules. 3. The apparent molecular weight, determined by equilibrium sedimentation of neurophysin-I, was 19000 and that of neurophysin-II was 21000; their sedimentation coefficients, S20,w, were 1·66 and 2·02s respectively. 4. Neurophysin-I and -II are similar in amino acid composition. Neurophysin-II was distinguished from neurophysin-I by the absence of histidine. 5. The proteins form complexes with oxytocin as well as with vasopressin. Complexes of both proteins with [8-arginine]-vasopressin have been crystallized. 6. Bioassay of the pressor and oxytocic activities of the crystals shows that neurophysin-I binds three molecules of either vasopressin or oxytocin whereas neurophysin-II binds only two molecules of each hormone per molecule of protein. Complexes containing two molecules of oxytocin and one molecule of [8-arginine]-vasopressin per molecule of protein are formed by neurophysin-I and -II; both proteins appear to possess three polypeptide-binding sites/molecule.
Aspartate aminotransferase. The effects of ionic concentration on kinetic constants of both isoenzymes
Authors: Boyde T. R. C.
Published: August 2015

1. The Michaelis constants for both isoenzymes for both substrates depend strongly on ionic concentration, being approximately proportional to phosphate concentration over considerable ranges. This is probably an effect of anions only. 2. In the absence of added salt, Km (2-oxoglutarate) (anionic isoenzyme) is so small as to be indeterminate. 3. Km (l-aspartate) (anionic isoenzyme) passes through a sharp minimum at about 3·3mm-phosphate. It is not clear whether this is a specific effect of phosphate. 4. Both substrates are inhibitory at sufficiently low ionic concentrations. 5. A modified graphical procedure is described for the derivation of the kinetic constants.
The significance of changes in tissue clearing-factor lipase activity in relation to the lipaemia of pregnancy
Authors: Otway Sheila , Robinson D S
Published: August 2015

1. The concentration of triglyceride fatty acid in the plasma of the pregnant rat rises to a maximum 2–4 days before parturition. Thereafter there is a rapid decline in the concentration to near normal values at parturition. 2. A similar increase occurs in animals fed on a diet low in fat. There is no increase in food consumption at the time when the triglyceride fatty acid concentration in the plasma is at its peak. 3. Rates of entry of triglyceride fatty acid into the blood during pregnancy have been estimated from the rate of accumulation of triglyceride in the plasma of animals injected with a non-ionic detergent, Triton. A progressive increase occurs in the entry rate as the body weight increases throughout pregnancy. Expressed per constant body weight, the entry rate does not change significantly. 4. Adipose-tissue clearing-factor lipase activity is low at the time when the plasma triglyceride fatty acid concentration is raised. Activity of the enzyme in heart, lung and diaphragm is unchanged. 5. It is suggested that the ‘lipaemia of pregnancy’ may be due to diminished uptake of triglyceride fatty acids by adipose tissue, and, further, that the disappearance of the lipaemia may be due to increased uptake of triglyceride fatty acids by the mammary gland.
A study of the alkaline hydrolysis of fractionated reticulocyte ribosomal ribonucleic acid and its relevance to secondary structure
Authors: Cox R A , Gould Hannah J. , Kanagalingam K
Published: August 2015

1. RNA isolated from the sub-units of rabbit reticulocyte ribosomes was hydrolysed by 0·4n-potassium hydroxide at 20°. The probability of main-chain scission was calculated from the number-average chain length, which was obtained from S25,w in 0·01m-phosphate buffer. 2. The fraction, f, of the original secondary structure that the fragments re-formed at neutral pH in 4m-guanidinium chloride, as well as in 0·01m- and 0·1m-phosphate buffer, was derived from changes in extinction over the range 220–310mμ on thermal denaturation. 3. The secondary structure of RNA is regarded as an assembly of hairpin loops each of 2N+b residues on average, where N is the number of base-paired residues and b is the number of unpaired residues. 4. If chain scission takes place at random then 2N+b=logf/log(1–p). 5. For RNA from the smaller sub-unit 2N+b was estimated as 25±5 residues, compared with 30±5 residues for the less stable species and 35±5 residues for the more stable species of hairpin loop of RNA from the larger sub-unit.
The effect of γ-irradiation on soluble collagen
Authors: Davidson R. J. , Cooper D. R.
Published: August 2015

1. A study was made of the effect of γ-irradiation on the sub-unit composition, as well as the conformational changes taking place in cooled solutions of thermally denatured neutral-salt-soluble and acid-soluble collagen. 2. The increase in negative rotation and viscosity at 15° for irradiated and thermally denatured collagen solutions becomes less as the irradiation dose is increased. 3. The initial effect of γ-irradiation is the depolymerization of the dimers found in both neutral-salt-soluble and acid-soluble collagen. 4. The principal effect of γ-irradiation up to 10 Mrads is the fission of peptide bonds, yielding crystalline irradiation-resistant portions of the molecule incapable of associating to the native structure. 5. The effects of γ-irradiation on both neutral-salt-soluble and acid-soluble collagen are very similar and bear a close resemblance to the effects induced by ultraviolet irradiation.
The partial sequence of two large peptides from the N-terminal half of heavy chains from normal rabbit immunoglobulin G
Authors: Cebra J. J. , Steiner L. A. , Porter R R
Published: August 2015

The partial amino acid sequence of two large peptides is described. These were prepared from the N-terminal half of the heavy chain of immunoglobulin G from pooled normal rabbit serum by tryptic digestion after the ∈-amino groups of the lysine residues had been blocked with S-ethyl trifluorothioacetate. These peptides are believed to account for about 145 residues of fragment C-1, the N-terminal section of rabbit immunoglobulin G heavy chain prepared by cyanogen bromide cleavage. The evidence from the present paper and the preceding paper (Cebra, Givol & Porter, 1968) suggests that it may be possible to deduce a predominant amino acid sequence for most, if not all, of this section of the molecule.
The chemical constitution of carcinolipin
Authors: Hradec J. , Dolejš L.
Published: August 2015

1. The neutral portion of the molecule of carcinolipin was found to be cholesterol by comparison of mixed melting points with cholesterol, its dibromide and its acetate. 2. The fatty acid present in carcinolipin was subjected to oxidative degradation by chromic acid and permanganate. Butan-2-one was the main neutral degradation product resulting from both these procedures. A mixture of dibasic acids was obtained after the oxidation with chromic acid. Permanganate oxidation yielded a complete homologous series of branched-chain C5–C17 fatty acids. 3. The mass spectrum of the acid was characteristic for a saturated C17 acid. The alcohol prepared by lithium aluminium hydride reduction of the original acid showed a mass spectrum typical for an anteiso compound. 4. Comparison of mixed melting points, gas–liquid-chromatographic behaviour and mass spectra of the fatty acid isolated from carcinolipin with an authentic sample of 14-methylhexadecanoic acid demonstrated the identity of these compounds. Cholesterol esters synthesized from authentic cholesterol and the fatty acid isolated from carcinolipin or synthetic 14-methylhexadecanoic acid showed an identical stimulating effect on the incorporation of labelled algal-protein hydrolysate into rat liver transfer RNA in vitro. 5. Mass spectra, results of oxidative degradations and comparisons with an authentic sample, as well as biological activity of the synthetic cholesterol 14-methylhexadecanoate, provided good evidence that carcinolipin is cholesterol (+)-14-methylhexadecanoate.
Occurrence of 7-methylguanine in nucleic acids of rat liver
Authors: Craddock Valda M. , Villa-Trevino S. , Magee P. N.
Published: August 2015

1. Microsomal and soluble RNA of rat liver have been studied by column and paper chromatography after administration of [Me−14C]methionine; evidence was obtained for the occurrence of 7-methylguanine, the methyl group being derived from methionine. 2. No evidence was obtained for the occurrence of 7-methylguanine in DNA.
The fluorescence of indoles and aniline derivatives
Authors: Bridges J W , Williams R T
Published: August 2015

1. The variations in the excitation and fluorescence wavelengths and fluorescence intensities of a number of indole and aniline derivatives over a wide range of acidity and alkalinity (36n-sulphuric acid to 10n-potassium hydroxide) have been studied. 2. The changes in fluorescence with pH of the indoles and anilines had many characteristics in common, and the most fluorescent species were found to be the non-ionized or neutral forms showing fluorescence maxima at about λ 350mμ. 3. In 10n-potassium hydroxide most of the compounds examined, except those containing a tertiary nitrogen atom, showed a bathochromic shift in fluorescence wavelength attributable to an anion due to a negatively charged nitrogen, but in strong acid (3n-sulphuric acid) these compounds were non-fluorescent, except the anisidines and the 5-hydroxyindoles. 4. p-Anisidine but not the o- and m-isomers showed excited-state ionization in acid solution. 5. Of the hydroxyindoles only the 5-hydroxy derivatives showed a fluorescence (λmax. 520–540mμ) in acid solution. It is suggested that this fluorescence is due to a proton-transfer reaction in the excited state, and various arguments for this suggestion are given. 6. Stokes shifts for the various ionic and neutral species of the indoles and anilines have been calculated, and the large shifts found with indole and p-anisidine may be due to solvent–solute interaction.
The relation between sodium ion content and efflux of labelled sodium ions from yeast
Authors: Dee Elizabeth , Conway Edward J.
Published: August 2015

1. The activity of the Na+ pump in an Na+-rich yeast was compared with that in an Na+-rich frog sartorius muscle, and found to be very similar to it over the first hour if both were immersed in fluid containing 104mm-Na+ plus 10mm-K+. 2. The efflux of labelled Na+ from an Na+-rich yeast into an Na+-free medium was investigated. In this Na+-free medium, Li+ or choline replaced the Na+, and the efflux–content curves obtained with either of these ions were very similar. The curves were sigmoid, reaching or approaching a saturation at the higher internal Na+ concentrations. 3. The curves obtained with yeast resembled those similarly obtained with frog sartorius muscle by Keynes & Swan (1959), Mullins & Frumento (1963), Harris (1965) and Keynes (1965). The slope of the plot of the logarithm of the Na+ efflux against the logarithm of the Na+ concentration in the cells reached its highest value at an internal Na+ concentration of 15m-equiv./kg. (27m-equiv./l. of cell water). 4. The effect of external K+ concentration on the efflux–content relationship was examined. An increased K+ concentration was found to increase the Na+ efflux by raising the saturation value, which is similar to observations made by Harris (1965) with frog muscle. 5. The effect of increasing the external carbon dioxide concentration was investigated. No effect on the slope of the plot of the logarithm of the Na+ efflux against the logarithm of the Na+ content was noticed even when the yeast suspension was equilibrated with 100% carbon dioxide. There was, however, a decrease in the amount of Na+ efflux on equilibrating the solution with carbon dioxide.
Sedimentation studies on the interaction of proflavine with deoxyribonucleic acid
Authors: Lloyd P. H. , Prutton R. N. , Peacocke A. R.
Published: August 2015

A method is described of using photography to measure the concentrations of a small ligand (proflavine) above and below the boundary of a macromolecule (DNA, both native and denatured) sedimenting in the ultracentrifuge. The measurements are used to determine the extent of the binding of proflavine to DNA, and the results compared with those obtained by a spectrophotometric method. The results obtained by the two methods agree within 10%, thus validating the spectrophotometric technique under these conditions. The variation of the sedimentation coefficient with the extent of binding of proflavine was also studied. The results are discussed in relation to previously observed changes in the viscosity of the solutions.
Amino acid uptake in the developing chick embryo heart. The effect of insulin on α-aminoisobutyric acid accumulation
Authors: Guidotti G. G. , Borghetti A. F. , Gaja G. , Lo Reti L. , Ragnotti G. , Foà P. P.
Published: August 2015

1. The uptake of 14C-labelled α-aminoisobutyric acid by 5-day-old chick embryo hearts was investigated in vitro, together with the effect of insulin thereon. 2. At equilibrium the distribution ratio of this amino acid analogue between intracellular and extracellular water attained values greater than unity. Insulin enhanced the rate of α-aminoisobutyric acid accumulation and increased the value of its final concentration in the cell water. 3. The rate of α-aminoisobutyric acid accumulation and the effect of insulin on it were independent of the presence of glucose in the incubation medium. Bovine and chicken insulin were equally effective, and the action of the hormone was specifically prevented by an anti-insulin serum but not by puromycin. 4. A linear relationship was observed between the intracellular accumulation of the analogue and the logarithm of the insulin concentration in the range 50μunits–100m-units/ml. of incubation medium. 5. Evidence was obtained for the occurrence of two different transport processes for α-aminoisobutyric acid in the chick embryo heart: one subject to saturation and one that was not saturated by reasonable concentrations of the analogue. Insulin increased the effectiveness of the saturable component, increasing the maximal velocity of transport without altering the concentration for half-maximal velocity of transport, and decreased the contribution of the non-saturable component.
Allotype-related sequence variation of the heavy chain of rabbit immunoglobulin G
Authors: Prahl J. W. , Porter R R
Published: August 2015

The heavy chain of rabbit immunoglobulin G exists in three major allotypic patterns, Aa1–Aa3. A comparison of the amino acid compositions of the heavy chains isolated from immunoglobulin IgG homozygous for each allotypic determinant revealed the presence of an additional methionine residue per chain in the Aa3 allotype relative to the Aa1 and Aa2 allotypes. The position of the additional methionine residue was determined by cyanogen bromide cleavage and by tryptic digestion of the γ-chains; it coincided with the inter-Fd–Fc area of the chain. Isolation and characterization of the corresponding tryptic peptides of 31 amino acid residues from each of the allotypes showed the presence of a methionine-for-threonine replacement in the Aa3 allotype, but only in about 70–80% of the molecules. No other allotypic variations were seen in this tryptic peptide. Allotypically related variations in composition were also detected in the N-terminal cyanogen bromide-cleavage peptide.
The interaction between α2-macroglobulin and cationic aspartate aminotransferase
Authors: Boyde T. R. C.
Published: August 2015

On starch-gel or polyacrylamide-gel electrophoresis of human serum, a supernumerary zone of aspartate aminotransferase activity may be demonstrated, migrating with the slow α2 protein zone. This appearance is due only to cationic aspartate aminotransferase, bound by α2-macroglobulin. The binding is strongly potentiated by dilute borate buffers.
Structure and species as factors affecting the metabolism of some methoxy-6-sulphanilamidopyrimidines
Authors: Bridges J W , Kibby M. R. , Walker S R , Williams R T
Published: August 2015

1. A comparative study was made in man, rhesus monkey, rat and rabbit of the urinary excretion of 2-, 4- and 5-methoxy- and 2,4-, 2,5- and 4,5-dimethoxy-6-sulphanilamidopyrimidines given orally. 2. In the rabbit, 70–80% of the dose of each drug was excreted in 2 days, mainly as N4-acetyl derivatives, except 2,5-dimethoxy-6-sulphanilamidopyrimidine, which was mainly excreted unchanged. 3. In the rat, 50–70% of the dose of each drug was excreted in 2 days, except the 2-methoxy and 2,4-dimethoxy compounds, whose excretion was about 30%. The N4-acetyl derivatives accounted for 20–70% of the drugs excreted, except the 2,5-dimethoxy derivative, which was excreted unchanged. 4. In the rhesus monkey, some 40–60% of the dose of the 2-methoxy, 2,4-dimethoxy and 2,5-dimethoxy compounds was excreted in 2 days, but the 4-methoxy, 5-methoxy and 4,5-dimethoxy compounds were excreted at less than half this rate. The 4-methoxy, 5-methoxy and 4,5-dimethoxy compounds were highly acetylated (80–90%) whereas the 2-methoxy compound was poorly acetylated (17%) and the 2,5-dimethoxy compound hardly at all. The major metabolite of the 2,4-dimethoxy compound in the monkey was the N1-glucuronide. 5. In man, 30% of the dose of the 4-methoxy and 2,4-dimethoxy compounds was excreted in 24 hr., whereas the 4,5-dimethoxy compound (Fanasil) was very slowly excreted (12% in 2 days). The 4-methoxy compound was well acetylated (65%), but the 2,4- and 4,5-dimethoxy compounds were not (20–30%). The main metabolite of the 2,4-dimethoxy compound in man was the N1-glucuronide. 6. N1-Glucuronide formation occurred extensively only with the 2,4-dimethoxy compound and only in man and the rhesus monkey. It did not occur in the rabbit and only to a minor extent in the rat. 7. The 2,5-dimethoxy compound was not significantly acetylated in vivo in the rabbit, rat or monkey, but acetylation occurred in vitro in rabbit or monkey liver homogenates. 8. These findings are discussed.
Pyruvate carboxylase in lactating rat and rabbit mammary gland
Authors: Gul Bilquis , Dils R.
Published: August 2015

1. Pyruvate carboxylase [pyruvate–carbon dioxide ligase (ADP), EC 6.4.1.1] was found in cell-free preparations of lactating rat and rabbit mammary glands, and optimum assay conditions for this enzyme were determined. 2. Subcellular-fractionation studies with marker enzymes showed pyruvate carboxylase to be distributed between the mitochondrial and soluble fractions of lactating rat mammary gland. Evidence is presented that the soluble enzyme is not an artifact due to mitochondrial damage. 3. In contrast, pyruvate carboxylase in lactating rabbit mammary gland is confined to the mitochondrial fraction. 4. The final product of pyruvate carboxylase action in the mitochondrial and particle-free supernatant fractions of lactating rat mammary gland was shown to be citrate. 5. The effects of freeze-drying, ultrasonic treatment and freezing-and-thawing on the specific activity of mitochondrial pyruvate carboxylase were investigated.
The effects of carbon tetrachloride on rat liver microsomes during the first hour of poisoning in vivo, and the modifying actions of promethazine
Authors: Slater T. F. , Sawyer B. C.
Published: August 2015

The effects of an oral administration of carbon tetrachloride on various liver microsomal and supernatant components were studied 1hr. and 2hr. after dosing. The modifications of such early changes resulting from a concomitant administration of promethazine together with the carbon tetrachloride were also investigated. The microsomal components studied were: cytochromes P-450 and b5; inorganic pyrophosphatase; NADH– and NADPH–cytochrome c reductases; NADH– and NADPH–neotetrazolium reductases; a lipid-peroxidation system associated with the oxidation of NADPH and stimulated by ADP and Fe2+. NAD– and NADP– DT-diaphorases were measured in the supernatant solution remaining after isolation of liver microsomes, and the distribution of RNA phosphorus between the microsomes and supernatant solution was also determined. Carbon tetrachloride produced a rapid fall in inorganic pyrophosphatase activity, a rather slower decrease in cytochrome P-450 content of the microsomes and small increases in the activities of NADH–cytochrome c reductase and neotetrazolium reductases. The activities of NADPH–cytochrome c reductase, the NADPH–ADP/Fe2+-linked lipid-peroxidation system, DT-diaphorases and the content of cytochrome b5 in the microsomes were unchanged. There was also a loss of RNA phosphorus from the microsomes into the supernatant solution. The RNA phosphorus redistribution, the decrease in inorganic pyrophosphatase and the increases in neotetrazolium reductase activities were at least partially prevented by a concomitant dosing with promethazine. However, the decrease in cytochrome P-450 was not affected by promethazine treatment. These early changes are discussed in terms of the liver necrosis produced by carbon tetrachloride and which is greatly retarded in its onset by the administration of promethazine.
Interactions between the lysine-rich histone F1 and deoxyribonucleic acid
Authors: Johns E. W. , Forrester Susan
Published: August 2015

1. The interactions of the lysine-rich histone F1 with DNA have been studied at various histone to DNA ratios, in water and in the presence of uni- and bi-valent cations. In water only, histone F1, even in fourfold excess, is unable to precipitate all the DNA. In 0·14m-sodium chloride, 0·8mg. of histone F1 is required to precipitate 1mg. of DNA, whereas in 0·07m-magnesium chloride only 0·4mg. is required. 2. Bivalent cations are also shown to be more effective in dissociating the DNA–histone complex. Histone F1 can be selectively removed from deoxyribonucleoprotein with 0·1m-magnesium chloride. 3. The precipitation of DNA by histone F1 is a reversible process and the complex can be taken in and out of solution by changing the ionic environment. 4. The bearing of these results on the observed ability of various DNA–histone complexes to act as templates for RNA synthesis is discussed.
Lipid metabolism. Evidence of a δ-oxidation pathway for saturated fatty acids
Authors: Dimick P. S. , Walker N. J. , Patton Stuart
Published: August 2015

1. Specific radioactivities of milk triglyceride fatty acids and γ- and δ-hydroxy fatty acids were measured after the intramammary infusion of [1−14C]acetate, δ-hydroxy[1−14C]laurate and [1−14C]laurate as their sodium salts into fed lactating goats. 2. Net incorporations of the radioactive tracer into the total milk lipids were comparable, being 16, 17 and 21% of the label infused respectively. 3. The specific radioactivities of the C4–C8 fatty acids after [1−14C]acetate infusion were lower than those of the C10–C14 fatty acids. 4. After δ-hydroxy[1−14C]laurate administration the milk triglyceride fatty acids were labelled and their specific radioactivities were characterized by decreasing values with increasing chain length of the fatty acids, implicating C4 unit incorporation. 5. The γ- and δ-hydroxy fatty acids isolated after [1−14C]laurate infusion were highly labelled and the milk triglyceride fatty acids, other than laurate, exhibited a labelling pattern similar to that of the fatty acids derived from the radioactive δ-hydroxy fatty acid. 6. Evidence is presented for the existence of saturated fatty acid δ-oxidation in the mammary gland, in which the γ- and δ-hydroxy fatty acids are active intermediates.