bluuebunny/crossref_metadata_2025 huggingface dataset:
Specific Activities of the UTP Pools of Human Lymphocytes After Uridine-3H Labeling
Authors: Fields T. , Brox L.
Published: December 2009

Human lymphocytes were labeled in vitro under various conditions with uridine-5-3H, and the specific activities of the acid-soluble UTP pools were determined by high-pressure liquid chromatography. Essentially, all the acid-soluble counts were in either UTP- or UDP-glucose. The relationship between the intracellular UTP specific activity, the extracellular uridine concentration, and the time of labeling demonstrates that the incorporation of uridine cannot be taken as a direct measure of RNA synthesis in these cells.
Isolation of Cerebroside from Alfalfa Leaves
Authors: Ito Seisuke , Fujino Yasuhiko
Published: December 2009

Cerebroside was isolated from alfalfa (Medicago sativa) leaves by solvent extraction, mild alkaline hydrolysis, and silicic acid chromatography. The purified material was identified as cerebroside by thin-layer chromatography, infrared spectrum, and chemical analysis. Hydrolysates of the cerebroside were divided into fractions of fatty acid, sugar, and long-chain base, and analyzed for the respective composition mainly by gas–liquid chromatography. The major component fatty acids were hydroxyhexadecanoic, hydroxydocosanoic, and hydroxytetracosanoic acids. Dehydrophytosphingosine and sphingosine were the predominant constituent long-chain bases. The component sugar was only glucose. Based on the results, one of the major species of alfalfa cerebroside is suggested to be N-hydroxyhexadecanoyl-glucopyranosyl-dehydrophytosphingosine.
β-Glucuronidase Isoenzymes of Rat-Liver Lysosomes
Authors: Potier M. , Gianetto R.
Published: December 2009

β-Glucuronidase (β-D-glucuronide glucuronohydrolase, EC 3.2.1.31) from liver lysosomes of male Sprague–Dawley rats was purified by (NH4)2SO4 precipitation, treatment with trypsin and gel filtration on Sephadex G-200, and then fractionated into five active components by ion-exchange chromatography on DEAE-Sephadex A-25 or DEAE-cellulose. All five isoenzymes were shown to be electrophoretically and ultracentrifugally homogeneous. Their sedimentation coefficients range from 12.27 to 13.39. All five isoenzymes appear to be glycoproteins.
Relative DNA Damage Induced in Cultured Human Skin Fibroblasts by Exposure to the Precarcinogen 2-Acetylaminofluorene, the Proximate Carcinogen N-Hydroxy-2-acetylaminofluorene, and the Ultimate Carcinogen N-Acetoxy-2-acetylaminofluorene
Authors: Laishes Brian A. , Stich H. F.
Published: December 2009

DNA damage in cultured human skin fibroblasts was induced by the ultimate carcinogen N-acetoxy-2-acetylaminofluorene at concentrations as low as 2 × 10−6 M. The precarcinogen 2-acetylaminofluorene and the proximate carcinogen N-hydroxy-2-acetylaminofluorene failed to induce measurable DNA damage. The extent of DNA damage was measured by a technique of velocity sedimentation through alkaline sucrose gradients; it increased with the applied concentration of N-acetoxy-2-acetylaminofluorene and the carcinogen 4-nitroquinoline-1-oxide. Measurement of DNA damage induced by 30-min exposure to 4 × 10−7 M 4-nitroquinoline-1-oxide indicated that the technique employed in this study is of greater sensitivity than those previously reported.
Lipid Absorption and Deposition in Rainbow Trout (Salmo gairdnerii)
Authors: Robinson J. Stephen , Mead James F.
Published: December 2009

Rainbow trout, fed or starved for 5 weeks, were force-fed 23 μCi 1-14C-palmitic acid and sacrificed at [Formula: see text], 1, 2, 4, 8, and 14 h after feeding. Analysis of the blood suggested that trout possess an intestinal absorption mechanism for lipid that is very different from that found in other animals. The fish, incapable of delivering triglyceride to its circulation in the usual way, receives most of its absorbed lipid as free fatty acids, probably via the portal system. It was also found that light muscle more easily yielded its triglyceride stores, in agreement with its role as the major lipid depot in trout. Nonetheless, dark muscle was metabolically more active in deposition of muscle lipids. Dark muscle appeared to function more as an organ than a kinetically responsible contractile body.
The Amino Acid Sequence of Streptomyces griseus Trypsin. I. The Peptic Peptides
Authors: Jurášek L. , Smillie L. B.
Published: December 2009

Streptomyces griseus trypsin (S.G.T.) isolated from pronase was digested with pepsin. The peptic peptides were isolated by high-voltage electrophoresis on paper and ion-exchange chromatography on Chromobead P resin using the Technicon autoanalyzer system. Analysis of the purified peptides provides 28 unique amino acid sequences accounting for approximately 95% of the S.G.T. molecule. A portion of the residues not accounted for can be ascribed to free leucine, phenylalanine, tyrosine, and tryptophan present in the peptic digest. The NH2-terminal sequence of S.G.T. was shown to be Val–Val–Gly–Gly–Thr–Arg–Ala–Ala–Gln–Gly–Glu–Phe and is highly homologous with NH2-terminal sequences of other Asp–Ser–Gly serine proteases.
Distribution and Metabolism of Tryptamine in Rat Brain
Authors: Wu P. H. , Boulton Alan A.
Published: December 2009

Following intraventricular injection in untreated rats, the only metabolites of tryptamine isolated were indoleacetic acid and indoleacetaldehyde; the indication is that the acid is formed from the aldehyde during the isolation procedure. Additional metabolites (N-methyltryptamine and N,N-dimethyltryptamine) were formed in small quantities if the animals had been pretreated with pargyline. N-acetyltryptamine was not found if acetate ions were excluded during the isolation of the amine fraction.More tryptamine remained in the hypothalamus than any other region at all times following injection, both in the presence and absence of pargyline. Incubation with slices indicated a temperature dependent active uptake process in all regions.The loss of injected tryptamine from all regions in the presence of pargyline, and from the hypothalamus, cerebellum, and 'rest' in the absence of pargyline followed a pattern of rapid initial loss and then slower decline. This pattern was neither linear nor exponential. All the data, however, indicate a rapid turnover of the injected amine.
Two Forms of Histone–Acetyltransferase in High Salt Extracts of Rat Liver Nuclei
Authors: Lue Peter F. , Gornall A. G. , Liew C. C.
Published: December 2009

Two forms of 'histone' acetyltransferase (AT I and AT II) were separated by DEAE-Sephadex chromatography of rat liver nuclear extracts prepared by sonication in 0.3 M (NH4)2SO4. A 12-fold greater amount of AT I was not adsorbed on the DEAE-Sephadex column, whereas AT II was adsorbed and was eluted with 0.15–0.2 M (NH4)2SO4. Chromatography of AT I on Sephadex G-200 and cellulose phosphate indicated the presence of additional forms of the enzyme. Optimal conditions for the assay of the enzyme have been determined.In vitro acetylation of calf thymus histone fractions by AT I or AT II showed that at low histone concentration (313 μg/ml), the "arginine-rich" fractions (f2a1 and f3) were acetylated to a greater extent than were the "lysine-rich" fractions (f1 and f2b). However, at a higher concentration of histone (1250 μg/ml) f2a1 acetylation decreased as a result of coprecipitation with the enzyme. Electrophoretic analysis of the acetylated fractions indicated that multiple sites were probably acetylated on f3, f2a2, and f2a1, whereas only one residue was reactive in f1 and f2b.Interconversion of AT I and AT II has been demonstrated and it was shown that [Formula: see text]. AT I contained mainly histones f2a2 and f3, and was converted to AT II by treatment with high salt and gel filtration chromatography. After hypotonic lysis of nuclei and DEAE chromatographic analysis of extracts obtained by washing the nuclear pellet with 0.3 M sodium citrate of NaCl, most of the acetylating activity in these extracts was identified as AT II. Thus the greater amount of AT I observed initially in (NH4)2SO4 extracts was probably a consequence of the sonication step used in this extraction procedure.
Nucleotide Clusters in Deoxyribonucleic Acids. VIII. The Pyrimidine Oligonucleotides of Bacteriophage S13 Wild Type DNA
Authors: Spencer John H. , Boshkov Lynn
Published: December 2009

A method for determination of the compositional assignment and comparison of the oligonucleotides in longer pyrimidine isostichs from closely related DNA's is described. The method is a dual 32P/33P labelling technique and has been used to investigate the pyrimidine oligonucleotide catalogue of bacteriophage S13 wild type DNA by comparison with the catalogue of the nitrous acid amber mutant S135suN15. The isomeric compositions of the dinucleotide CTp3 and trinucleotides CT2p4 and C2Tp4 from both DNA's were examined also. No cytosine (C) → thymine (T) transitions had occurred in the longer pyrimidine isostichs 7–11 inclusive, which constitute 10% of the catalogue of each of the two S13 DNA's, the catalogues of the two DNA's being indistinguishable.
The Amino Acid Sequence of the N-Terminal Region of Some 30 S Ribosomal Proteins from Escherichia coli and Bacillus stearothermophilus: Homologies in Ribosomal Proteins
Authors: Yaguchi M. , Roy C. , Matheson A. T. , Visentin L. P.
Published: December 2009

The sequence of the amino terminal region of fifteen 30 S ribosomal proteins from Escherichia coli and three proteins from Bacillus stearothermophilus are compared.
Attempts to Find a Specific Intranuclear Location for Replicating Polyoma Virus DNA
Authors: Frost E. , Bourgaux P.
Published: December 2009

Attempts were made to localize the site of replication of polyoma virus DNA in mouse embryo cells. Although newly synthesized viral DNA was clearly confined within the nucleus, no evidence was found to indicate that replication takes place either on the nuclear membrane, or in the nucleolus, or in association with any other large structure. In all nuclear fractions examined, the mature and replicative forms of the viral DNA were found in the same proportions, but as parts of DNA–protein complexes with unique sedimentation properties.
Molecular Species of Glycerolipids of Adenosine Triphosphatase and Sarcotubular Membranes of Rabbit Skeletal Muscle
Authors: Marai L. , Kuksis A.
Published: December 2009

The molecular species of choline, ethanolamine, serine, and inositol phosphatides and triglycerides were determined in purified adenosine triphosphatase and in the parent sarcotubular membranes of rabbit skeletal muscle. The total membrane and the adenosine triphosphatase were essentially identical in the composition of lipid classes and closely similar in patterns of molecular species of the corresponding phosphatides and triglycerides. The phosphatidylcholines were made up largely of the 1-palmitoyl 2-oleoyl and 1-palmitoyl 2-linoleoyl species. The ethanolamine phospholipids contained mainly the plasmalogens 1-palmitaldehyde 2-arachidonoyl and 1-stearaldehyde 2-arachidonoyl along with smaller amounts of the 1-palmitaldehyde 2-oleoyl and 1-palmitaldehyde 2-linoleoyl species. The phosphatidylinositols, which were analyzed along with about 10% phosphatidylserine, were characterized by large proportions of 1-stearoyl 2-arachidonoyl and smaller but significant proportions of the 1-stearoyl 2-oleoyl, 1-stearoyl 2-linoleoyl, and 1-stearoyl 2-eicosatrienoyl species. The triglycerides contained significant proportions of tripalmitin, triolein, and the isomeric palmitoyl oleoyl linoleins.The composition and molecular association of the fatty acids in these phosphatides showed significant differences from that of other tissues of the rabbit and other animals, as far as they have been analyzed, except for phosphatidylinositol, the structure of which was similar to that found elsewhere. The triglyceride composition was unusual in the high content of simple triglycerides.
Phospholipid and Protein Metabolism in Mouse Liver Mitochondria During Riboflavin Deficiency and Recovery
Authors: McMurray W. C. , Rogers L.
Published: December 2009

A study was made of the effect of riboflavin deficiency and recovery upon the structure and function of mitochondrial membranes in mouse liver. In the deficient animals the mitochondria were enlarged and contained reduced numbers of inner membrane profiles. The activity of enzymes of the inner membranes (succinate cytochrome c reductase, cytochrome oxidase) was reduced in the deficient mitochondria, as was the content of diphosphatidylglycerol, an inner membrane phospholipid; monoamine oxidase, a mitochondrial outer membrane enzyme, and the coupling reactions of oxidative phosphorylation did not appear to be affected. Incorporation in vivo of 32Pi into phospholipids and of 3H-leucine into proteins of deficient mitochondria was normal or somewhat enhanced. Following the administration of riboflavin to the deficient mice, liver mitochondria appeared to undergo division, and inner membrane profiles seemed more numerous. Riboflavin administration increased the 3H labelling of tightly bound mitochondrial proteins, and decreased the 32P labelling of the phosphatidylcholine fraction.
Intracellular Distribution of Steroid Glycosidases of Rabbit Liver
Authors: Mellor Joyce D. , Layne Donald S. , Irvin Jean E. , Mellors Alan
Published: December 2009

The activity and intracellular distribution of several glycosidases in rabbit liver have been examined. Glycosides of the steroid estrogens, which have been shown to occur naturally in the rabbit, were used as substrates and the results were compared to those obtained when synthetic p-nitrophenyl glycosides were used. β-N-acetylglucosaminidase (EC 3.2.1.30) and β-glucuronidase (EC 3.2.1.31) activities were concentrated in the lysosomes and showed the latency typical of lysosomal acid hydrolases. β-D-Glucosidase (EC 3.2.1.21) activity was concentrated in the unsedimentable fraction of the liver homogenates and did not exhibit latency. No differences were found in the intracellular distribution of glycosidase activities towards the steroid and the p-nitrophenyl glycosides.
Toxicity, Analysis, and Production of Aspergillic Acid and its Analogues
Authors: MacDonald J. C.
Published: December 2009

A differential analysis, utilizing the decomposition of 3,6-disubstituted-1-hydroxy-2(1H) pyrazinones (HPYs) by ultraviolet light, was developed to measure low concentrations of total HPYs (aspergillic acid and/or its analogues) in cultures.Two strains of Aspergillus flavus were found to differ in their ability to produce aflatoxins and HPYs on liquid media composed of 2% yeast extract and varying amounts of sucrose. Production of HPYs by both strains was best in the absence of sucrose and production of aflatoxins was best on media containing 10–20% sucrose. The better producer of HPYs was strain PRL 932, but when it was grown on moist seeds of peas, barley, maize, or wheat, it produced only traces of these compounds.In a separate study, two analogues of aspergillic acid were tested for toxicity in mice. The toxicity of a novel analogue, 3-(2-(methylthio)-ethyl)-6-sec-butyl-1-hydroxy-2(1H) pyrazinone, was the same as that of a more common analogue, neoaspergillic acid.
Calcium Enhancement of Protein Synthesis in Rat Heart Ventricles
Authors: Kaplan Eli , Richman Harold G.
Published: December 2009

The effect of calcium on protein synthesis was studied in myocardial ventricular slices.Calcium in concentrations ranging from 0.01 to 4.0 mM increased the incorporation of leucine into proteins of all the subcellular fractions. Maximal protein synthesis occurred at concentrations of 0.5–2.5 mM calcium, and [14C]-leucine incorporation into proteins was linear for the 4-h incubation period only in the presence of calcium.In all experiments, the specific activity of [14C]-leucine in the sarcoplasm was not different either in the absence or in the presence of calcium. Optimal protein synthesis in the myocardium depends on the presence of calcium.
Comparative Study of Molecular Species of Glycerolipids in Sarcotubular Membranes of Skeletal Muscle of Rabbit, Rat, Chicken, and Man
Authors: Marai L. , Kuksis A.
Published: December 2009

The major classes of neutral lipids and the molecular species of choline, ethanolamine, serine, and inositol phosphatides were determined in the sarcotubular membranes of the skeletal muscle of rabbit, rat, chicken, and man. All membrane preparations contained qualitatively the same lipid classes, but certain significant quantitative differences occurred. The largest discrepancies were noted in the phosphatidylethanolamines, which ranged from about 17% in rabbit to 24% in man and also varied in their plasmalogen content. The sarcotubular membranes of the rat, rabbit, and man contained minor amounts of cardiolipin (2%), which may have represented a mitochondrial contamination. Despite considerable variation in the component fatty chains, the molecular weight distributions of corresponding glycerolipids showed considerable similarity among the different animal preparations. The phosphatidylethanolamines of the rat, however, contained large amounts of 16:0 22:6 and 18:0 22:6 at the expense of 16:0 18:1 and 18:0 18:1, whereas in the phosphatidylserines of the rat and chicken, the 18:0 22:6 was substituted for 18:0 22:4 in the rabbit and man. The membranes contained variable amounts of neutral lipid, and gave molar ratios of phospholipid to cholesterol ranging from 2 to 4. The triglycerides possessed similar structures in all four membrane preparations. Comparisons with the molecular species of lipids of other tissues revealed significant differences in the constitution of all glycerolipids except phosphatidylinositols and cardiolipins, which were similar in all membranes. Little variation was also seen in the molecular species of the sphingomyelins.
Structural Characteristics of Hydrated Glycerol- and Sphingo-lipids. A Spin Label Study
Authors: Boggs J. M. , Hsia J. C.
Published: December 2009

(1) The structural organization and fluidity of a variety of lipid classes were studied by electron spin resonance spectroscopy of fully hydrated planar films labeled with 3-doxyl-cholestane and 5-doxyl-palmitate and of dispersions labeled with 5-doxyl-palmitate. The phase of each lipid was checked by use of a polarizing microscope.(2) Orientation in a lamellar phase was detected for phosphatidyl-choline, -ethanolamine, -inositol, phosphatidic acid, cardiolipin, ceramide, and sphingomyelin. In the presence of 33 or 50 mol % cholesterol, the orientation was improved in all of these lipids with the exception of cardiolipin and orientation was induced in phosphatidylserine, monoglycerides, sphingosine, and cerebrosides. Cholesterol fluidized the sphingolipids sufficiently to solubilize the spin labels and allow formation of oriented multibilayers by this method.(3) Anisotropic motion of 5-doxyl-palmitate was also seen in films and disperions of 1-monoglycerides and diglycerides and in dispersions of gangliosides, which are known to exist in hexagonal or micellar phases.(4) The contribution of the molecular structures to the stability of the lamellar phase is discussed.
Biosynthesis of Gibberellins in Gibberella fujikuroi. Gibberellin A16
Authors: McInnes A. G. , Smith D. G. , Arsenault G. P. , Vining L. C.
Published: December 2009

A metabolite isolated from cultures of Gibberella fujikuroi has been deduced from infrared, nuclear magnetic resonance, and mass spectrometric evidence to be the hitherto undescribed gibberellin A16. Cultures supplemented with gibberellin A4-14C yielded radioactive gibberellin A16, whereas those to which gibberellin A7-14C were added yielded unlabeled product. Thus gibberellin A16 is probably formed by direct C-1 hydroxylation of gibberellin A4.
Distribution of 14C-Isotope in Stereoisomers of Serine
Authors: Kent S. Sherrill
Published: December 2009

A method is described for the analysis of the intramolecular distribution of 14C-isotope in micromole amounts of low activity L-serine. The 3-carbon compound is degraded enzymically with L-serine dehydratase and carbon atoms 2 and 3 are incorporated, as acetyl-CoA, into citrate (C-1,2). The specific activity of carbon atoms 2 and 3 of serine may be obtained directly by the application of the citrate colorimetric assay as a degradation procedure. The error in the determination of the specific activity of the individual carbon atoms of serine is routinely less than 3%. The method may be adapted for the separate analysis of stereoisomeric forms of serine (and other compounds degradable to acetate) in biological materials.
Biosynthesis of Sphingomyelin in Developing Brain Tissues
Authors: Sribney Michael , Duffe Marilyn K. , Lyman Eileen M.
Published: December 2009

The properties of the enzyme phosphorylcholine–ceramide transferase (CDP-choiine:ceramide cholinephosphotransferase, EC 2.7.8.3) which catalyzes the biosynthesis of sphingomyelin has been studied in brain tissues of the developing rat, chick, and calf. This enzyme catalyzes the transfer of the phosphorylcholine moiety from the coenzyme CDP-choline to the free primary hydroxyl group of threo-ceramides containing short-chain fatty acids in acyl linkage. Free erythro- or threo-sphingosines and erythro-ceramides with either short- or long-chain fatty acids in acyl linkage do not act as acceptors of phosphorylcholine in these tissues. In contrast to chicken liver these brain tissues do not catalyze the menadione-stimulated formation of sphingomyelin from erythro-cetamidts. Brain tissues have been found to inhibit the menadione-stimulated formation of sphingomyelin catalyzed by chicken liver mitochondria. Other properties of brain phosphorylcholine–ceramide transferase are also described.
Synthesis and Acid Hydrolysis of Monophosphate and Pyrophosphate Esters of Phytanol and Phytol
Authors: Joo C. N. , Park C. E. , Kramer J. K. G. , Kates M.
Published: December 2009

Monophytanyl phosphate was synthesized by phosphorylation of phytanol with diphenylphosphoryl monochloride followed by catalytic hydrogenolysis of the phenyl groups; the product was isolated as the dipotassium salt. The phytanyl pyrophosphate was prepared by phosphorylation of phytanol with monophenylphosphoryl dichloride followed by aminolysis and saponification of the resulting phytanylmonophenylphosphoryl monochloride to the phytanyl phosphoramidate. The latter, as the cyclohexylamine salt, was reacted with dioxane diphosphate in the presence of pyridine to give the desired phytanyl pyrophosphate isolated as the tripotassium salt. Alternatively, the phytanyl pyrophosphate was made from phytanyl monophosphate via the phosphomorpholidate. The 2-phytenyl (phytyl) pyrophosphate was synthesized more directly by phosphorylation of phytol with di-(triethylammonium) phosphate in the presence of trichloroacetonitrile in acetonitrile as solvent. The phytyl pyrophosphate and the accompanying phytyl monophosphate were isolated as tri- and diammonium salts, respectively. These mono- and pyrophosphates were characterized by elementary analysis, infrared spectra, and behavior towards acid hydrolysis; the hydrolysis products formed are characteristic of the phytyl or phytanyl phosphate hydrolyzed and may be used for their identification.
Biosynthetic Precursors of Etamycin, a Peptidolactone Antibiotic from Streptomyces griseoviridus
Authors: Hook D. J. , Vining L. C.
Published: December 2009

Radiotracer studies of the incorporation of labeled amino acids have established the biosynthetic precursors of etamycin. L-[U-14C]threonine and L-[U-14C]alanine were incorporated into the corresponding moieties in the antibiotic. Sarcosine was derived from [1-14C]glycine but [1-14C]sarcosine was also an efficient precursor. L-[U-14C]leucine was incorporated equally well into the D-leucine and N-β-dimethyl-L-leucine moieties. L-α-Phenylsarcosine originated from phenylalanine, the carboxyl-, α-, and phenyl-carbons being derived from 14C-labeled α-, β-, and phenyl-carbons of the precursor. A small incorporation of L-[carboxy-14C]phenylalanine into the carboxyl-carbon of phenylsarcosine was also observed. L-[Me-14C]methionine labeled the methyl groups of sarcosine, phenylsarcosine, and the two substituent methyl groups of dimethylleucine. L-[U-14C]proline and 4-hydroxy-L-[G-3H]proline were both incorporated efficiently into the allo-4-hydroxy-D-proline component of etamycin. 3-Hydroxypicolinic acid was labeled specifically by L-[U-14C]lysine, and also by exogenousiy supplied 3-hydroxy[G-3H]picolinic acid.
Isolation of Novel Conjugated Gibberellins from Cucumis sativus Seed
Authors: Hemphill Jr. Delbert D. , Baker L. R. , Sell H. M.
Published: December 2009

Neutral and n-butanol fractions of a methanol extract of mature seeds of a monoecious line of Cucumis sativus (cucumber) were found to contain novel gibberellins. A β-D-glucoside was isolated from the n-butanol fraction and partially characterized by thin-layer chromatography as a derivative of gibberellin A1. The n-propyl ester of GA3 was isolated from the neutral fraction and the n-propyl ester of GA1 was tentatively identified as a second component of that fraction.
Studies on Partially Purified Pig Liver Steroid Δ4-5β-Reductase Activity
Authors: Doorn Edward J. Van , Nduaguba John C. , Clark Albert F.
Published: December 2009

Some properties of partially purified steroid Δ4-5β-reductase activity of pig liver cytosol have been studied using testosterone as substrate. The enzymatic activity was stable for 72 h at 4° when stored in 0.05 M Tris–maleate buffer, pH 7.4 or 8.4; storage at pH 8 at 4° resulted in a 25% decrease in activity in 30 days. The pH optimum in Tris–maleate buffers was 6.4. Enzyme activity was completely inhibited by 0.2 mM p-chloromercuribenzenesulfonate and 0.2 mM p-chloromercuribenzoate. Enzyme activity was reduced by 20% and 45% with 1.0 mM iodoacetamide and 1.0 mM N-ethylmaleimide, respectively. The end products of the enzymatic reaction, NADP+ and 5β-dihydrotestosterone, inhibited the rate of reduction of testosterone. Testosterone Δ4-5β-reductase activity was present in protein of molecular weight 25 000–30 000, as determined by gel filtration.The enzyme preparation reduced a variety of C19 and C21 steroids. The highest activity (twice that for testosterone) was found with aldosterone as substrate.
A Possible Role for 5 S rRNA as a Bridge Between Ribosomal Subunits
Authors: Azad A. A. , Lane B. G.
Published: December 2009

18 S rRNA is a high molecular weight polyribonucleotide found in the small subunit, and 26 S rRNA is a high molecular weight polyribonucleotide found in the large subunit, whereas 5 S rRNA and 5.8 S rRNA are low molecular weight ("satellite") polyribonucleotides confined to the large subunit of wheat-embryo ribosomes. Under the same conditions in which 5.8 S rRNA is known to complex efficiently and preferentially with 26 S rRNA, it has been observed that 5 S rRNA complexes efficiently and preferentially with 18 S rRNA. Since 5 S rRNA is a component of the large ribosomal subunit, but it complexes preferentially with 18 S rRNA, which is a component of the small ribosomal subunit, it has been proposed that 5 S rRNA may serve as a "bridge" to mediate reversible association between the small and large ribosomal subunits. The possible role that a polycistronic precursor of rRNA might be visualized to play in the biogenesis and assembly of reversibly associating ribosomal subunits is alluded to in the present context.
Some Aspects of the Dietary Sodium Intake on the Regulation of Aldosterone Biosynthesis in Rat Adrenals
Authors: Lehoux Jean-Guy , Sandor Thomas , Henderson I. W. , Jones I. Chester
Published: December 2009

Experiments were performed to study the effect of dietary sodium deficiency on the in vitro biosynthesis of corticosteroids from tritiated cholesterol by homogenates of whole adrenal glands and on the properties of rat adrenocortical cytochrome P-450. Adrenal homogenates of rats kept on a sodium deficient diet for 17 days converted 3 times more tritiated cholesterol to corticosterone, 15 times more to 18-hydroxycorticosterone, and 6 times more to aldosterone than did homogenates from rats kept on the control diet. While adrenocortical cytochrome P-450 content did not differ significantly in the glands of experimental animals from that of control animals, changes could be observed in the cytochrome P-450 – carbon monoxide association time constants (KCO).
The Occurrence and Properties of Soluble UDP-Galactose:Glycoprotein Galactosyltransferase in Human Amniotic Fluid
Authors: Nelson J. D. , Jato-Rodriguez Juan J. , Mookerjea Sailen
Published: December 2009

Human amniotic fluid obtained by amniocentesis during the third trimester of pregnancy has been found to contain the enzyme for transferring galactose from UDP-galactose into various exogenous acceptors. The enzyme galactosyltransferase is present in soluble form and does not require Triton for activity. The optimum pH (pH 6.8), divalent cation requirement (Mn2+, 12.5 mM), optimum temperature (37 °C), and linearity with time and enzyme concentrations have been established. The amniotic fluid enzyme catalyzed the transfer of 60 nmol of galactose to fetuin acceptor per milliliter of amniotic fluid per hour and its apparent Km for UDP-galactose is 9.1 × 10−5 M. The enzyme is stable to storage at −20 °C for at least 2 months. Acid hydrolysis and β-galactosidase treatment of the labelled reaction product released all of the radioactivity as 14C-galactose. Uridine nucleotides inhibited the soluble enzyme whereas the adenine and cytidine nucleotides had no appreciable effect. The addition of α-lactalbumin in the assay caused the appearance of lactose synthetase activity and inhibition of N-acetyllactosamine synthetase activity. The specific activity of the enzyme in the amniotic fluid in human and rat is 30- to 40-fold higher than in their serum. Placenta, fetal liver, and fetal lungs of rat also showed considerable enzyme activity.Enzymes that transfer N-acetylglucosamine, sialic acid, and N-acetyl-4-galactosamine from their respective nucleotide sugars to exogenously added acceptors are also present in human amniotic fluid.
Plasma Oxytocinase: The Synthesis and Biological Properties of the First Prodoct of the Degradation of Oxytocin by this Enzyme
Authors: Ferrier B. M. , Hendrie J. M. , Branda L. A.
Published: December 2009

Oxytocin is hydrolytically cleaved in the presence of plasma oxytocinase to give an acyclic peptide, tyrosyl-isoleucyl-glutaminyl-asparaginyl-S-(S-cysteine)-cysteinyl-prolyl-leucyl-glycinamide (1,2-acyclic oxytocin). The synthesis of this peptide is described. It is shown to be of very low potency in milk-ejection-like activity and uterotonic activity. It does not inhibit the expression of these activities by oxytocin, suggesting that it does not interfere with the hormone's binding to target tissues. The presence of 1,2-acyclic oxytocin slightly inhibits the rate of degradation of oxytocin by plasma from pregnant women, in contrast to the marked inhibition of the degradation of cystine di-β-naphthylamide. The Km for the degradation of oxytocin is 30 times smaller than that of the degradation of cystine di-β-naphthylamide, which is of the same order as the Ki for the inhibition of the degradation of cystine di-β-naphthylamide by 1,2-acyclic oxytocin. These results, together with information on the substrate specificity of plasma oxytocinase with respect to the N-terminal amino acid residue, suggest that there are molecular features of oxytocin other than its N-terminal residue that facilitate its interaction with plasma oxytocinase.
Autoreduction of Pure Spinach Cytochrome f: A Light-Dependent Process Inhibited by 3-(3,4-Dichlorophenyl)-1,1-dimethylurea
Authors: Garewal Harinder S. , Stuart Allan L. , Wasserman Aaron R.
Published: December 2009

A new procedure for the complete purification of spinach (Spinacea oleracea) cytochrome f, a tightly bound membrane protein, is described. The autoreduction of pure spinach cytochrome f has been confirmed using this new preparation. The process is now shown to be light-dependent and completely inhibited by the photosynthetic inhibitor 3-(3,4-dichlorophenyl)-1,1-dimethylurea. This inhibition is reversed by removing the inhibitor. The possible physiological implications of these observations are discussed.
Effects of Potassium Depletion in Rats on Renal Organic Ion Transport
Authors: Hirsch G. H.
Published: December 2009

Accumulation of the organic acid p-aminohippurate was significantly depressed in renal cortical slices from potassium-deficient rats, and when slices were incubated in potassium-free medium. The uptake of the organic base N-methylnicotinamide was not as sensitive to low potassium, whereas gluconeogenesis was enhanced after potassium depletion. All values returned to near control levels when potassium-depleted rats were refed normal diet.
Metabolism of Na275SeO4 in Horseradish: Formation of Selenosinigrin
Authors: Stewart J. M. , Nigam S. N. , McConnell W. B.
Published: December 2009

Metabolism of Na275SeO4 in horseradish has been investigated. The leaves and a seedling were given Na275SeO4, and the glucosinolate sinigrin was isolated from them. The isolated sinigrin was found to contain selenium. It is suggested that the selenium in this fraction was present as selenosinigrin.
Studies of the Metabolism of Asialotransferrins: Potentiation of the Catabolism of Human Asialotransferrin in the Rabbit
Authors: Regoeczi E. , Hatton M. W. C. , Wong K.-L.
Published: December 2009

The catabolism and distribution of simultaneously injected rabbit transferrin and rabbit asialotransferrin was studied in five rabbits using a dual-isotope tracer technique. Similar studies were performed with human transferrin and human asialotransferrin in two humans, seven rabbits, and a rat.In all experiments, the catabolic rate of the asialotransferrin was higher than the corresponding value for the control protein. The difference averaged at 15% for rabbits and 29% for humans when homologous protein preparations were used. There were no concomitant differences in capillary transfer rates or in the partition of the labeled proteins between intra- and extravascular spaces.The catabolic rate of human transferrin in rabbits was not significantly different from that of the corresponding homologous protein. In contrast, human transferrin from which 92–100% of the sialyl residues had been removed was catabolized in rabbits at approximately 3.5 times the rate for homologous asialotransferrin. Substantial difference was found between the elimination of human control and asialotransferrins in the rat as well.
Antibodies to Indolealkylamines; Serotonin and Melatonin
Authors: Grota Lee J. , Brown Gregory M.
Published: December 2009

Serotonin, N-acetyl serotonin, and 5-methoxy-N-acetyl serotonin (melatonin) were conjugated to bovine serum albumin (BSA) using formaldehyde. The molar ratio of hapten to protein was determined spectrophotometrically. Spectrophotometric data indicated that serotonin and N-acetyl serotonin but not melatonin were conjugated to bovine serum albumin. Selected hapten–protein conjugates were suspended in Freund's adjuvant and injected into rabbits. Antisera were harvested monthly and screened by double immunodiffusion. Immunodiffusion and inhibition tests indicated that antibodies raised to serotonin–BSA reacted with serotonin and 5-methoxytryptamine but failed to cross react with N-acetyl serotonin or melatonin. Inhibition tests indicated that antibodies to N-acetyl serotonin – BSA reacted with N-acetyl serotonin and cross reacted with melatonin but not with serotonin or 5-methoxytryptamine.
The 4.5 Å Resolution Structure of a Bacterial Serine Protease from Streptomyces Griseus
Authors: Codding P. W. , Delbaere L. T. J. , Hayakawa K. , Hutcheon W. L. B. , James M. N. G. , Jurášek L.
Published: December 2009

Three crystalline modifications of the bacterial serine peptidase Streptomyces griseus Protease B have been grown. A 4.5 Å resolution electron density map of one form has been computed from the multiple isomorphous replacement (MIR) phases deduced from two heavy metal derivatives plus the anomalous dispersion effects of one of the derivatives. The crystalline modification used was grown from 0.7–1.0 M KH2PO4 at pH 4.2. These crystals have space group P21212 and unit cell dimensions of a = 44.15 (5) Å, b = 108.72 (10) Å, and c = 37.28 (5) Å. The crystal asymmetric unit contains a protein mass of approximately 19 000 daltons. The electron density map, mean figure of merit 0.80, clearly shows the molecular boundary; relatively long stretches of extended chain are discernable. The active site has been identified from a difference electron density map computed using the MIR protein phases and the amplitude differences between a crystal of the enzyme inhibited at the active serine in solution by p-iodobenzenesulfonyl fluoride (PIPSYL) and those from a crystal of the native enzyme. In addition to showing the site of the PIPSYL binding, there is an apparent conformational change in which the histidine side chain moves away from the serine residue by approximately 4.3 Å.
Biosynthesis of the Diguanosine Nucleotides. I. Purification and Properties of an Enzyme from Yolk Platelets of Brine Shrimp Embryos
Authors: Warner A. H. , Beers P. C. , Huang F. L.
Published: December 2009

An enzyme that catalyzes the synthesis of P1P4-diguanosine 5′-tetraphosphate (Gp4G) has been isolated and purified from yolk platelets of encysted embryos of the brine shrimp, Artemia salina. The enzyme GTP:GTP guanylyltransferase (Gp4G synthetase) utilizes GTP as substrate, has a pH optimum of 5.9–6.0, a temperature optimum of 40–42 °C, and requires Mg2+ and dithiothreitol for optimal activity. The synthesis of Gp4G is inhibited markedly by pyrophosphate, whereas orthophosphate has no effect on the reaction. In the presence of GDP the enzyme also catalyzes the synthesis of P1,P3-diguanosine 5′-triphosphate (Gp3G), but the rate of synthesis is low compared with Gp4G synthesis and dependent upon other small molecular weight components of yolk platelets.
Biosynthesis of the Diguanosine Nucleotides. II. Mechanism of Action of GTP:GTP Guanylyltransferase on Nucleotide Metabolism in Brine Shrimp Embryos
Authors: Warner A. H. , Huang F. L.
Published: December 2009

The enzyme GTP:GTP guanylyltransferase (Gp4G synthetase) from yolk platelets of embryos of the brine shrimp, Artemia salina, catalyzes the synthesis of P1P4-diguanosine 5′-tetraphosphate (Gp4G) and pyrophosphate (PPi) from 2 equiv of GTP in a freely reversible reaction. The Michaelis constant (Km) for GTP in the forward reaction is 2.2 mM, whereas the Km for Gp4G and PPi in the reverse reaction is 1.06 mM and 0.84 mM, respectively. Also, the yolk platelet enzyme catalyzes the synthesis of P1P3-diguanosine 5′-triphosphate (Gp3G) and GTP from equivalent amounts of GDP and Gp4G. Both GDP and Gp3G inhibit the synthesis of Gp4G and the kinetic data suggest that either two enzymes are present in the Gp4G synthetase preparations or that two catalytic sites exist on one protein, one for the synthesis of Gp3G and one for the synthesis of Gp4G. Almost 80% of the Gp4G synthetase in embryos of Artemia salina is localized in yolk platelets, and a small amount of activity is found in the mitochondrial fraction.
The Subcellular Distribution of Some Monoamines Following their Intraventricular Injection into the Rat
Authors: Boulton Alan A. , Baker Glen B.
Published: December 2009

The subcellular distribution of radioactively labelled p-tyramine, octopamine, β-phenylethylamine, tryptamine, and N-methyltryptamine, 30 min after their intraventricular injection, was investigated and compared with the distributions of equimolar amounts of the putative transmitters noradrenaline, dopamine, and 5-hydroxytryptamine injected under identical conditions. The amount of each labelled amine, and any formed labelled amine metabolites, in each subcellular fraction was assessed using chromatographic techniques. The effect of the presence of Na+ and various buffer solutions on the distribution of radioactivity between particulate and supernatant fractions, particularly with respect to tryptamine, was investigated.
The Site of Protein Synthesis in the Moss Tortula ruralis on Recovery from Desiccation
Authors: Tucker Edward B. , Bewley J. Derek
Published: December 2009

The major ribosomal species in the rehydrated moss Tortula ruralis had a sedimentation value of 80 S. The electrophoretic mobility of the major rRNA from T. ruralis was the same as the mobility of rRNA from wheat germ, but was different from the mobility of rRNA from Escherichia coli. In vivo protein synthesis upon rehydration of the dehydrated moss was inhibited 80% in the presence of cycloheximide. Upon rehydration of dehydrated T. ruralis it appears that the polyribosomes that are present are composed of cytoplasmic-type ribosomes.
Synthesis of Albumin with Exogenous Mouse-Liver Messenger RNA in a Homologous Cell-Free System
Authors: Faber A. J. , Miall S. H. , Tamaoki T.
Published: December 2009

RNA extracted from total and membrane-bound polysomes of mouse liver was capable of directing protein synthesis in a homologous cell-free system in the presence of a 0.5 M KCl ribosomal wash fraction. Analysis of the products by polyacrylamide gel electrophoresis and immunoprecipitation showed that newly formed albumin could account for up to 8% of the total protein synthesized.
Identification and Distribution of Tryptamine in the Rat
Authors: Philips S. R. , Burden D. A. , Boulton A. A.
Published: December 2009

A procedure for the quantitative measurement of tryptamine in mammalian tissues is described. The amine is isolated by ion-exchange chromatography, converted to its dansyl derivative, further purified by thin-layer chromatography, and quantitated by the mass-spectrometric integrated ion current technique using an isotopically labelled internal standard.The concentrations of tryptamine in some tissues of male Wistar rats were (ng/g ± S.D.): brain 0.50 ± 0.07, heart 0.62 ± 0.10, kidney 8.04 ± 2.10, liver 0.73 ± 0.07, lung 0.54 ± 0.18, and spleen 0.43 ± 0.14. In the brain, the hypothalamus contained 0.94 ± 0.22, the cerebellum 0.27 ± 0.02, the stem 0.24 ± 0.06, the caudate nucleus 2.93 ± 1.14, and the "rest" 0.32 ± 0.05 ng/g (mean ± mean deviation).
Sarcolemmal ATPase Activities in Normal and BIO 14.6 Dystrophic Hamster Skeletal Muscle
Authors: Wrogemann K. , Jacobson B. E. , Blanchaer M. C.
Published: December 2009

Increased Na+–K+-ATPase activities are observed in skeletal muscle sarcolemmal fractions of genetically dystrophic hamsters in advanced disease stages. A decline with age is seen in Na+–K+-ATPase activities in normal hamsters, which is not paralleled by the Na+–K+-ATPase activities in dystrophic animals. In young animals the sarcolemmal ATPase activities of normal and dystrophic muscle are indistinguishable. The data therefore do not support the membrane hypothesis of muscular dystrophy. Freezing decreases Mg2+-ATPase and increases Na+–K+-ATPase activities. Heparin has no effect on freshly isolated sarcolemmal ATPases, but partially prevents the freezing effect. The response to freezing and/or to heparin is indistinguishable between preparations from normal and dystrophic muscle.
Glycosphingolipids in Secondary Lysosomes Prepared from Rat Liver
Authors: Huterer S. , Wherrett J. R.
Published: December 2009

Glycosphingolipid classes were isolated from unfractionated liver and from the buoyant fraction of secondary lysosomes following pretreatment of rats with Triton WR-1339. They were identified by thin-layer chromatography and by sugar analysis using gas chromatography and were quantified by estimating long chain base. Hematoside containing N-acetyl neuraminic acid, glucosyl, lactosyl, trihexosyl, and galactosamine-containing tetrahexosyl ceramides were identified in unfractionated liver in the following concentrations, respectively: 0.89, 0.59, 0.19, 0.06, and 0.1 nmol/mg protein. The same glycosphingolipid classes were identified in buoyant Triton-filled lysosomes where their respective concentrations in terms of protein were 8.6, 21, 28, 34, and 28 times as great as in unfractionated liver. The lysosome fraction was enriched 28-fold in acid phosphatase. These results demonstrate that some glycosphingolipid classes are concentrated in secondary lysosomes to a degree expected of markers for primary lysosomes and plasma membrane. Secondary lysosomes are thought to be derived from these latter two structures.
Microsomal Synthesis of Di- and Triacylglycerols in Rat Liver and Ehrlich Ascites Cells
Authors: O'Doherty P. J. A. , Kuksis A.
Published: December 2009

The overall activity and specificity of the acyltransferases involved in triacylglycerol biosynthesis were compared in microsomes of normal rat liver and Ehrlich ascites cells using a variety of synthetic mono- and diacylglycerols of known structure as substrates. The ascites cell microsomes converted 2-monoacyl-sn-glycerols to diacylglycerols (25–67 nmol/h per milligram protein) at about two to three times the rate of liver microsomes (9–26 nmol/h per milligram protein). They yielded two to three times more 2,3-diacyl-sn-glycerols (15–26%) than did liver microsomes (6–12%), although the major product of acylation of the 2-monoacyl-sn-glycerol was the 1,2-isomer (73–85%). The microsomes of the ascites cells converted two to three times as much 2,3-diacyl-sn-glycerol to triacylglycerol as did liver microsomes, although both tissues acylated 1,2-diacyl-sn-glycerols preferentially (58–85%). It is suggested that the ascites cells may have reverted to a more primitive stage of lipid metabolism characterized by the ability of direct esterification of the products of lipase activity.
Reaction of Alantolactone, an Allergenic Sesquiterpene Lactone, with some Amino Acids. Resultant Loss of Immunologic Reactivity
Authors: Dupuis G. , Mitchell J. C. , Towers G. H. N.
Published: December 2009

A study of the reaction of a hapten, alantolactone, with some amino acids is reported. Previously, we have reported than an α-methylene group attached to the γ-lactone is the immunologic requisite of alantolactone and some other sesquiterpene lactones. Such a group is known to be capable of undergoing "Michael-type addition" with the sulfhydryl group of cysteine. We confirm this finding and report that alantolactone can also undergo addition with the imidazole group of histidine and with the ε-amino group of lysine, but not with the guanido group of arginine, the hydroxyl group of serine, or the thio ether function of methionine. We selected these amino acids for further study because of their nucleophilic side chain. Samples of alantolactone that have undergone such addition no longer produce allergic eczematous contact dermatitis, as measured by patch test.
Circular Dichroism Spectra of DNA of High Adenine plus Thymine Content
Authors: Helleiner C. W. , Verpoorte J. A.
Published: December 2009

The ultraviolet circular dichroism spectra of the DNA of 10 bacterial species, all with mole percent adenine plus thymine equal to or greater than 50 were measured. The overall shapes of the spectra resembled those reported by others, but the values of the residue ellipticity at the spectral extrema departed increasingly from expected values for DNA of increasing adenine plus thymine content. For the DNA of most extreme base composition examined, that from Mycoplasma orale (mole percent adenine plus thymine, 75.6) the ratio of the ellipticity at the minimum near 245 nm to that at the maximum near 275 nm was 1.92. These values suggest that the secondary structure of DNA of very high adenine plus thymine content differs from that of DNA of less extreme base composition. A structure of the C type is postulated.