bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structure of the Sugar Components of the Quinocycline Complex
Authors: Matern Ulrich , Grisebach Hans , Karl Wolfgang , Achenbach Hans 
Published: March 2005

The sugar components of quinocycline A and isoquinocycline A and of quinocycline B and isoquinocycline B could be obtained as methylglycosides by methanolysis of the antibiotics with methanol‐trifluoroacetic acid. The NMR spectrum of the α‐ and β‐methylglycosides of the sugar from quinocycline A and isoquinocycline A is fully consistent with the structure 2,6‐dideoxy‐4‐C‐[1′‐hydroxyethyl]‐l‐xylo‐hexopyranose (Fig, 1, compound III, R = H, α‐anomer) deduced from previous chemical studies and from an X‐ray analysis of isoquinocycline A. The absolute configuration at C‐5 of compound III was confirmed as l by isolation of l‐(+)‐lactic acid after periodate oxidation. The α‐ and β‐methylglycosides of the sugar from quinocycline B and isoquinocycline B show in the mass spectrum a molecular ion (C9H16O5) possessing 2 hydrogen atoms less than that of the methylglycosides of compound III (C9H18O5). For one of the two anomeric methylglycosides from quinocycline B and isoquinocycline B the structure α‐O‐methyl–2,6‐dideoxy‐4‐C‐[1′‐oxoethyl]‐l‐xylo‐ or l‐ribo‐hexopyranoside (Fig.3, compound IVa or IVb) was deduced mainly from the NMR spectrum and by isolation of l‐(+)‐lactic acid after periodate oxidation. The relative configuration of the hydroxyl groups at C‐3 and C‐4 as trans (compound IVa) was established by the fact that the methylglycoside does not form a borate complex. The carbonyl function of compound IVa gives a sharp band at 1740 cm−1 in the infrared.The structure of compound IVa was confirmed by the formation of the α‐methylglycoside of compound III (R = CH3) as one product of sodium borohydride reduction of the α‐methylglycoside, compound IVa. The sugar of quinocycline B and isoquinocycline B is therefore 2,6‐dideoxy‐4‐C‐[1′‐oxoethyl]‐l‐xylo‐hexopyranose.
Enzyme Localization in Beef‐Heart Mitochondria
Authors: Addink Albert D. F. , Boer Pieter , Wakabayashi Takashi , Green David E. 
Published: March 2005

Treatment of heavy beef heart mitochondria with different concentrations of digitonin, followed by centrifugation of the treated suspension resulted in a release of mitochondrial enzymes in a certain order. Monoamine oxidase and rotenone‐insensitive NADH cytochrome c reductase were found primarily in the outer membrane fraction. At low concentrations of digitonin adenylate kinase and creatine kinase were in part released pointing to an intracristal localization; the remainder of these enzymes was found to be associated with the inner membrane‐matrix fraction. The soluble citric cycle enzymes were found in the inner membrane‐matrix preparation. They were released from the matrix in two groups: (a) isocitrate dehydrogenase, malate dehydrogenase, fumarase and aconitase and (b) 2‐oxoglutarate dehydrogenase, pyruvate dehydrogenase and lipoate dehydrogenase. Enzymes intrinsic to the inner membrane were released at concentrations of digitonin higher than 0.4 mg/mg protein (cytochrome oxidase, succinate dehydrogenase, ATPase and 3‐hydroxybutyrate dehydrogenase). The absence of citric cycle enzyme activity, except succinate dehydrogenase in submitochondrial particles prepared by sonication, also points to a localization of these enzymes in the matrix.From the experiments with the digitonin method it is concluded that the majority of the shared mitochondrial enzymes has a similar localization both in beef heart and rat liver mitochondria.Detergents such as digitonin, Lubrol WX and Titron X‐100 induce the “twisted” configuration of the inner membrane of beef heart mitochondria, suspended in a sucrose medium, as visualized electron microscopically.
The Preparation and Properties of Triosephosphate Isomerase from Chicken Muscle and a Comparison with that from Rabbit Muscle
Authors: Mcvittie John D. , Esnouf Michael P. , Peacocke Arthur R. 
Published: March 2005

A method is described for the purification of the enzyme triosephosphate isomerase from chicken breast muscle. The physical properties are compared with those of triosephosphate isomerase from rabbit muscle.

The enzyme prepared from chicken muscle was homogeneous as judged by electrophoresis in polyacrylamide gels and equilibrium sedimentation studies.
The molecular weight of the native chicken muscle enzyme was 48400 ± 700 (S.D.) and the subunits had a molecular weight of 25000 ± 1000 (S.D.). The values obtained for the rabbit muscle enzyme were 50500 ± 1500 (S.D.) and 26000 ± 1000 (S.D.), respectively.
On the basis of sedimentation velocity runs with various molarities of guanidinium chloride as solvent, the separation of subunits and the unfolding of these subunits was shown to occur simultaneously upon denaturation of the chicken muscle enzyme.
Some preparations of guanidinium chloride, which was used as a denaturant, were shown to possess lytic activity.
The Structure of Erythrocyte Membranes
Authors: Capaldi Roderick A. 
Published: March 2005

The membrane proteins of beef erythrocyte ghosts have been fractionated on the basis of their different interactions with lipid. The individual proteins in each fraction have then been characterized by polyacrylamide gel electrophoresis. Fractions I and II, which were solubilized from the membrane by distilled water and 1.2 M NaCl, respectively, amounted to 46% of the total membrane protein and included virtually all the polypeptide‐chains with molecular weights greater than 200000. These proteins must be linked to the membrane by predominantly ionic interactions, indicating that they are extrinsic proteins of the erythrocyte membrane.A considerable proportion of membrane protein (fraction III) was not liberated by distilled water or 1.2 M NaCl but could be separated from lipids by sodium dodecylsulphate, a reagent which disrupts hydrophobic interactions. 10 different polypeptides were identified in this fraction, including four glycoproteins. One polypeptide of molecular weight 87000 accounted for about half of the protein‐staining components. The proteins in this fraction are likely to be intrinsic membrane proteins which penetrate deeply into the lipid bilayer of the erythrocyte membrane.
Effects of a Glucocorticoid on the Concentrations of CoA and Carnitine Esters and on Redox State in Bovine Liver
Authors: Baird G. David , Heitzman Raymond J. , Snoswell Alan M. 
Published: March 2005

In this study, the hepatic concentrations of free and acetylated CoA and carnitine, and also hepatic redox state, have been determined in normal lactating cows and in lactating cows to which voren (dexamethasone 21‐pyridine‐4‐carboxylate) was administered 48 h previously.
The values for the hepatic [CoA]/[acetyl‐CoA] and [carnitine]/[acetylcarnitine] ratios in the normal cow were found to be lower than the corresponding values previously reported for other species. Voren administration brought about an increase in both these ratios. Only the increase for the [CoA]/[acetyl‐CoA] ratio was statistically significant, however.
Using the lactate dehydrogenase and glutamate dehydrogenase systems, respectively, values were obtained for the cytosolic and mitochondrial [NAD+]free/[NADH]free ratios in normal bovine liver that were similar to the corresponding values previously obtained for rat liver. Following voren administration there was a fall in the cytosolic value for this ratio and a rise in the mitochondrial value, so that the equilibrium between the cytosolic and mitochondrial redox states appeared to be disrupted.
Following voren administration there was an increase in the degree of reduction of total NAD.
The results are discussed in relation to the antiketogenic action of voren in the cow.
Proton‐Relaxation‐Enhancement Studies on the Binding to Yeast Pyruvate Kinase of a Substrate and Effectors
Authors: Fell David A. , Peacocke Arthur R. , Dwek Raymond A. 
Published: March 2005

The binding to yeast pyruvate base of Mn2+ has been determined from the enhancement of the proton relaxation rate which it causes. There were further changes in this enhancement in the presence of a substrate (phosphoenolpyruvate) and the effector (fructose diphosphate) and, from these changes, information was derived about their binding.
Both strong and weak binding sites for Mn2+ on the enzyme were detected.
The affinity of the enzyme for phosphoenolpyruvate was increased when the fructose diphosphate · Mn complex was bound to the enzyme.
The proton relaxation enhancement results indicated that there were not more than two sites for fructose diphosphate · Mn, and two sites for phosphoenolpyruvate in the presence of the fructose diphosphate · Mn complex, but that there may have been more than two sites for phosphoenolpyruvate in the presence of Mn2+ only.
Structural Studies of Alcohol Dehydrogenase from Rat Liver
Authors: Jörnvall Hans , Markovič Oskar 
Published: March 2005

The amino acid composition of alcohol dehydrogenase from rat liver was determined. Tryptic peptide maps of the carboxymethylated protein were compared with those of the corresponding derivative of the horse enzyme. Large peptides, not ordinarily resolved by this method, were redigested with thermolysin or chymotrypsin to permit a comparison of the entire proteins. The amino acid sequences of peptides of special interest were determined.A subunit molecular weight close to 40000 is established for rat liver alcohol dehydrogenase. The protein is homologous to the corresponding equine and human enzymes; sequence analysis of about one‐fifth of all residues in the protein chain of the rat enzyme shows a structural identity of about 80% among the subunits of the enzymes from man, horse and rat. The rate of evolution in alcohol dehydrogenase is estimated. Species differences of special structural or functional interest include exchanges of cysteine residues and of amino acids adjacent to the “active‐site” cysteine residue.No evidence was detected for subunits of different primary structures in rat liver alcohol dehydrogenase; neither the subunit differences characteristic for the human nor for the equine isoenzymes were found. It thus seems as if isoenzymes of liver alcohol dehydrogenase have evolved independently in these three species.
Are Serum Lipoproteins Esterases?
Authors: Kaminski Marie , Dubois Philippe 
Published: March 2005

The immune precipitates of high‐density lipoprotein of duck serum with rabbit antisera are active on an esterase substrate, while the high‐density lipoprotein itself is not active.The immune precipitates formed by high‐density lipoprotein with isolated immunoglobulins, either in agar gel or in liquid medium, were also shown to be inactive.Such inactive immune precipitates can become active through interaction with a component of rabbit serum.Investigations on the conditions of the reaction and first observations concerning the nature of the activating component are reported.
Über die Wechselwirkung des Actinomycin C3 mit Mono‐, Di‐ und Oligonucleotiden
Authors: Schara Reinhard , Muller Werner 
Published: March 2005

Sequence specificity in the binding of the actinomycins to DNA has been studied by measuring the dissociation constants of several deoxyribodinucleotide‐actinomycin complexes by spectral‐titration. Additional data for some mononucleotides and for a deoxyribotetranucleotide have been collected for comparison. The results show that:G‐Containing dinucleotides form complexes of roughly 10 times higher stability than G‐free dinucleotides. These data parallel the corresponding results for mononucleotides [16].The G‐containing dinucleotides may be subdivided into three classes of the following sequential types:a) d(pX‐G), which bind the actinomycins with similar affinity as the dGMP,b) d(pG‐X), which bind the actinomycins less strongly than dGMP, andc) d(pG‐C), which binds the actinomycins in a 2:1 complex (two dinucleotides per dye molecule) of higher stability than all the other dinucleotides.The tetranucleotide d(pC‐T‐A‐G) behaves as the dinucleotides of type a.Molecular weights of the complexes as determined by sedimentation equilibrium measurements confirmed the stoichiometry of the actinomycin‐d(pG‐C) complex obtained by titration. Corresponding measurements for the actinomycin complexes of d(pC‐G) and d(pC‐T‐A‐G) revealed that the antibiotic strongly favours double helix formation of these self complementary oligonucleotides, yielding 2:2 complexes with two equivalent binding sites at the ends of the helices.All data are consistent with fixation of the actinomycin chromophore on the 3′‐side of the dG‐residue as in the actinomycin‐dG crystal [8].
The “Free” Lipids of Two Different Strains of Hydrogen‐Oxidizing Bacteria in Relation to Their Growth Phases
Authors: Thiele Otto Wolfgang , Dreysel Jörg , Hermann Dieter 
Published: March 2005

Two strains of hydrogen‐oxidizing bacteria were used: Hydrogenomonas eutropha strain H16 and strain 11/x. The former is a gram‐negative flagellated rod and has been relatively well known with respect to its morphological, physiological, and biochemical properties. The latter is a gram‐positive, non spore‐forming, motile small rod the definite classification of which is unknown as yet.Both strains were grown chemolithotrophically in submerged culture with a limited nitrogen‐source and supplied with a gas mixture of H2, O2, and CO2. The lipid composition of the bacteria was determined at the end of the exponential phase (I), at the storage phase (II), and after reutilization of storage material (III).Along with the accumulation of poly(3‐hydroxybutyric acid) as the major storage material in strain H16 the amount of other lipids was shown to increase 1.8‐fold at phase II and to decrease at phase III. There is little or no change in the lipid pattern in various growth phases. It is suggested that the 1.8‐fold increase of the latter lipids during phase II is due to the synthesis of membrane lipids that are required for the formation of membranes surrounding the intra‐cellular granules of accumulating poly(3‐hydroxybutyric acid).In strain 11/x the amount of lipids increases 7 times along with an equal increase of carbohydrates at phase II. The majority of accumulated lipids consists of triglycerides free of significant amounts of unusual acyl group. It is suggested that there is a true storage of triglycerides that are reutilized during phase III.The lipid pattern of strain H16 is characterized by a high proportion of “strongly bound lipids” that consist predominantly of phospholipids. Characteristic lipid components are phosphatidylethanolamine, phosphatidylglycerol, and diphosphatidylglycerol, while coenzyme Q8 (0.41 μmol/g bacterial dry weight) has been found among the neutral lipids. A C17 cyclopropane acid (probably cis‐9,10‐methylene hexadecanoic acid) is present in all saponifiable lipids.The lipid pattern of strain 11/x is characterized by a high proportion of “loosely bound lipids” that consist predominantly of neutral lipids, particularly of triglycerides. Among the polar lipids, diphosphatidylglycerol and phosphoinositides are most abundant, and several unknown phospholipids are also present. No cyclopropane fatty acid has been found. The possible use of strain 11/x as a source of nutritional fat is discussed.
The Conversion of [4‐3H]Fructose and of [4‐3H]Glucose to Liver Glycogen in the Mouse
Authors: Hue Louis , Hers Henri‐Géry 
Published: March 2005

[4‐3H,6‐14C]Fructose or [4‐3H,6‐14C]glucose were injected into mice and the recovery of the two isotopes in liver glycogen was measured. As a mean, the 3H/14C ratio in glycogen was 36.6 and 51.8% of that in the injected fructose and glucose, respectively. From the comparison of these two ratios, the loss of tritium proper to fructose metabolism was equal to 29.2%. In the same experiments, the C‐6 to C‐1 randomization proper to fructose metabolism was, as a mean, equal to 27.4%. These findings are in agreement with the hypothesis that the glyceraldehyde formed in the liver upon aldolic splitting of fructose 1‐phosphate is metabolized by phosphorylation into glyceraldehyde 3‐phosphate under the action of triokinase. The oxidation of d‐glyceraldehyde into d‐glycerate would have resulted in a complete loss of tritium in glycogen. Furthermore, the 3H/14C ratio in d‐glyceraldehyde formed from fructose was the same as in the precursor despite the fact that the aldehyde dehydrogenase discriminates against [1‐3H]glyceraldehyde. Our results therefore preclude any important participation of the glycerate pathway in the metabolism of fructose.In the isolated rat diaphragm, the loss of tritium relative to 14C was of the order of 20%, for both glucose and fructose, confirming that, in muscle these two sugars are converted to glycogen by the same pathway.When incubated in vitro with a liver preparation deprived of glucose 6‐phosphatase, doubly labelled UDPG lost no 3H relative to 14C. Doubly labelled hexose 6‐phosphates underwent a rapid loss of tritium in the same conditions, and this loss was cancelled by fructose diphosphate. It appears probable that the tritium loss is due to an interconversion of hexosephosphates with pentosephosphates, the hydrogen exchange occurring at the level of the pentosephaosphate 3‐epimerase.In agreement with an exchange of hydrogen at the level of hexose 6‐phosphates in the liver, it was observed that the decay of [4‐3H]glucose in the blood is faster than that of [U14C]glucose.
Deoxyribonucleoside Triphosphate Pools of Normal and Transformed Baby‐Hamster‐Kidney Cells
Authors: Bjursell K. Gunnar , Reichard Peter A. , Skoog K. Lambert 
Published: March 2005

Pools of the four deoxyribonucleoside triphosphates were determined during growth in tissue culture of baby hamster kidney normal cells and cells transformed either by wild‐type polyoma virus or a temperature‐sensitive mutant of polyoma (ts‐3). The cells are transformed by ts‐3 at 31°C but lose most of their transformed character at 39°C. The three cell lines did not show any major differences with respect to pool sizes at 39°C: during rapid growth, dCTP formed the largest and dGTP the smallest pool, while the dATP and dTTP pools were of intermediate size. On cessation of growth all pools decrease in size; the decrease was very pronounced for dCTP but slight for dATP.The results at 31°C were similar to those at 39°C with one exception: the two transformed lines contained about twice as much dTTP as the normal cell line under comparable growth conditions. Our results suggest that after transformation a change occurs in the control of one or several of the enzymes leading to the synthesis of dTTP. This change is manifested only at the lower temperature.
Transcription in vitro of T3 DNA by Escherichia coli and T3 RNA Polymerases
Authors: Dunn John J. , Mcallister William T. , Bautz Ekkehard K. F. 
Published: March 2005

RNA isolated from Escherichia coli infected by bacteriophage T3 was sedimented through sucrose gradients. The size distributions of the mRNA species coding for three T3‐specific enzymes, the S‐adenosyl‐l‐methionine cleaving enzyme (adenosylmethioninase), phage RNA polymerase and lysozyme, were then investigated by using the fractionated RNA to program a cell‐free protein‐synthesizing system followed by enzymatic analysis of the translation products. Identical analyses of transcripts produced in vitro by E. coli and T3 RNA polymerases were performed and it was found that E. coli RNA polymerase, in conjuncton with termination factor (ϱ), was capable of synthesizing early mRNA species (mRNA for adenosylmethioninase and phage polymerase) apparently identical in size and coding capacity to those isolated from infected cells. Transcripts synthesized by the T3 RNA polymerase, while consisting predominantly of late RNA species, were found to contain functional mRNAs for adenosylmethioninase, phage RNA polymerase and lysozyme.The transcription patterns obtained are consistent with the assignment of one promotor for the region situated near the left terminus of the genome.
Protein A Isolated from Staphylococcus aureus after Digestion with Lysostaphin
Authors: Sjöquist John , Meloun Bedrich , Hjelm Hans 
Published: March 2005

Previous methods which have been used for the preparation of protein A, such as thermal release of protein A with lysozyme from the bacteria, have given a heterogenous product in a low yield. The present publication reports the isolation procedure of protein A from Staphylococcus aureus digested by lysostaphin for 2 h at 37°C. 450—500 mg of protein A was obtained from 300 g of wet bacteria. The preparation is homogenous as seen from its disc electrophoretic pattern.Amino acid composition was determined and based on a molecular weight of 42000. The number of amino acid residues found was 378 ± 6. Less than 0.2% hexosamines was present. The ultraviolet spectrum and the absorption coefficient, A1%275nm= 1.65 of protein A is given. Less than 0.1 mol amino terminal amino acid per mol protein was detected which indicates that the protein has a blocked N‐terminal amino acid. The protein was slowly digested with a mixture of carboxypeptidase A and B and 2 mol lysine/mol protein was released.Precipitation of protein A with normal human γ‐globulin gave an IgG: protein A molar ratio of 2.1:1 within the equivalence zone.The results are discussed with regard to the subunit structure of the protein and the type of attachment of protein A to the peptidoglycan part of the cell wall.
Zymogen‐Enzyme Transformations
Authors: Abita Jean‐Pierre , Lazdunski Michel , Bonsen Pieter P. M. , Pieterson Wim A. , de Haas Gerard H. 
Published: March 2005

Transformation of prophospholipase A into phospholipase A is triggered by the tryptic hydrolysis of the Arg7‐Ala8 bond of the zymogen. This bond is a better substrate for trypsin than the corresponding strategic bonds of other zymogens such as trypsinogen and chymotrypsinogen A or B: Km= 2.2 mM, kcat= 7 s−1 at pH 8, 1°C. Calcium ions which have an essential role in phospholipase catalysis play no role in prophospholipase activation.A comparative physico‐chemical analysis of the zymogen and of the enzyme shows that activation produces only very limited changes in the overall folding of prophospholipase. A structural rearrangement occurs at the N‐terminal end of the precursor. An excellent fluorescence reporter group to follow this conformational modification is the side‐chain of tryptophan‐3 (in phospholipase sequence) which passes from a polar to an apolar environment during activation.The α‐amino group of alanine‐1 (in the phospholipase sequence) which appears on activation is essential for enzyme activity. Selective chemical modification of this function by a number of reagents abolishes phospholipase activity.By analogy with the chymotrypsinogen‐chymotrypsin and the proelastase‐elastase transformations, it is proposed that the α‐amino group is involved in the formation of a salt‐bridge which stabilizes the adequate geometry of the active site. Evidences in favor of this hypothesis include the high pK and the low chemical reactivity of the α‐amino group, together with the resistance of native phospholipase to aminopeptidase degradation.