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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of sampling conditions on the levels of adenine nucleotides, pyridine nucleotides, glycolytic intermediates and related metabolites in yeast has been studied. A systematic examination of the conditions for harvesting has shown that it can be best accomplished by rapid filtration. Delays in the handling for removal of the medium, as is usual in the process of obtaining a number of data reported in the literature, lead to important changes in some of the metabolites examined. It is also shown that when a washing is imperative it can be carried out with a methanol-water mixture (50/50, v/v) cooled at -40 degrees without loss of intracellular concentrations of non-readily diffusible metabolites. On the basis of this experience the outline of a generally applicable procedure is presented.
Mol Cell Biochem 1976 Nov 30
PMID:Determination of intermediary metabolites in yeast. Critical examination of the effect of sampling conditions and recommendations for obtaining true levels. 1 64

The lower Vmax of 6PGDH with respect to G6PDH and its higher sensitivity to inhibition by NADPH, suggest the existence of an imbalance between the two dehydrogenases of the pentose phosphate pathway in rat liver. Possible modulators of these activities, particularly in relation with the inhibition by NADPH in physiological conditions, have been investigated. The results suggest that in both cases the inhibition by NADPH is strictly isosteric and that the relative affinities for the reduced and oxidized forms of the pyridine nucleotide are unaffected by glutathion, the intermediates of the pentose phosphate shunt or some divalent ions.
Mol Cell Biochem 1977 Oct 07
PMID:Effectors of glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase of rat liver. 2 33

Interaction of bovine serum albumin (BSA) with quaternized poly-4-vinyl pyridine (PE) in aqueous solutions at pH 7 was studied. It was shown that in a wide range of the ratios of the components (nBSA/nPE) soluble stable cooperative complexes were formed. At the same time a certain critical content of the protein exists at which the system loses its homogeneity. Complex formation is not accompanied by protein denaturation. At smaller nBSA/nPE ratios non-homogeneous distribution of protein globulas among polyelectrolite macromolecules was found; this corresponded to the "all or none" principle. Using ultracentrifugation technique viscosimetric measurements and electron microscopy it was shown that the soluble complexes exist in the form of rode-like particles consisting of protein globules stabilized by polycation chains. Such particle can be considered as a model of nucleoprotein complex. At certain crytical nBSA/nPE rations the rod-like particles aggregate with additional number of BSA-molecules and form more complicate soluble and insoluble cooperative complexes. Possible structural models of the complexes described were suggested and the thermodinamic and kinetic cryteria of their self-assembly were discussed.
Mol Biol (Mosk)
PMID:[Cooperative interaction of serum albumin with quaternized poly-4-vinyl pyridine and structure of the complexes]. 3 35

Spin-labeled analogues of vitamin B6: 2, 2, 6, 6-tetramethyl-N-oxylpiperydinyl-4-(5' phosphopyridoxyl)-amine (1) and 2, 2, 6, 6-tetramethyl-N-oxyl-piperydinyl-4-(pyridoxal-5')-phosphate (II) are synthesized. There analogues were shown to interact in the equimolar ratio with the active site of cytosol aspartate transaminase. It was proved by CD-titration of apotransaminase with I and II and by competition between the coenzyme and synthesized analogues. The free valency of spin-labeled coenzymes immediately disappears after interaction with the apoenzyme due to iminoxyl group reduction. The binding of I and II with the apoenzyme is accompanied by oxidation of one of the inner cysteine residues. The reactivation of the modified apoenzyme with PLP is not less than 65% of original transaminase activity. The analysis of space-filling atomic models of synthesized compounds allows to conclude that the distance between the centre of pyridine ring of the coenzyme and the modified thiol group is not more than 8 A.
Mol Biol (Mosk)
PMID:[Interaction of spin-labeled analogues of vitamin B 6 with the active site of apotransaminase]. 17 69

The energy metabolism of rat thymus cells has been investigated using preparations of isolated cells obtained by mechanical treatment of whole organs. The addition of glycolytic substrates such as glucose, pyruvate and lactate stimulates the endogenous respiration of these cells by 50%. On the other hand, succinate, glutamate and malate do not produce any effect. Oligomycin (10 mug/ml) inhibits both endogenous and glucose stimulated respiration by about 40%; 2, 4-DNP (50 muM) increases by 100% glucose induced respiration. The results obtained by using mitochondrial and glycolytic inhibitors as well as aminoxyacetic acid (AOA) and following pyridine nucleotides redox changes, support the idea that in thymus cells glucose is able to induce a great enhancement of O2 consumption both by raising the level of endogenous pyruvate and feeding the mitochondrial respiratory chain with cytosolic reducing equivalents, through an active malate-aspartate shuttle. Thymus cells exhibit a high Pasteur effect (74%). Both AOA and 2,4 DNP are able to stimulate aerobic lactate accumulation by 200% and 100% respectively, indicating that either the redox or phosphate potential do influence the rate of aerobic glycolysis in isolated thymus cells. Similar experiments are also reported on other cells with well known biochemical characteristics.
Mol Cell Biochem 1975 Jul 31
PMID:Energy metabolism of isolated rat thymus cells. 24 Oct 10

3-Aminopyridine adenine dinucleotide phosphate (AADP) was prepared from NADP and 3-amino-pyridine through the pig brain NADase-catalyzed pyridine base exchange reaction. The purified dinucleotide was chemically characterized and spectral properties of the compound were determined. The importance of the application of AADP in studies of NADP-requiring biochemical processes was indicated by the demonstration of AADP as an effective inhibitor of five NADP-requiring enzymes, by the demonstration of the fluorescence enhancement on the binding of AADP to yeast glucose-6-phosphate dehydrogenase when glucose-6-phosphate is present, and by the functioning of AADP as a fluorimetric substrate for snake venom nucleotide pyrophosphatase.
Mol Cell Biochem 1975 Aug 30
PMID:Studies of 3-aminopyridine adenine dinucleotide phosphate. 24 Oct 12

The intermolecular interaction of bacteriochlorophyll c and its pheophytin was studied in nonpolar solvents and solid films with the aid of absorption and infra-red (in the region of 1800--1600 and 3800--3000 cm-1) spectra. The influence of water removing and its addition on these spectra has been investigated. Besides the effect of pyridine treatment and pigment concentration were examined. The self-assemblage of all types of bacteriochlorophyll c aggregated forms absorbing in the range 680--745 nm is due to the formation of intermolecular bonds in which keto groups of cyclopentanone rings take part. Keto groups form coordinate bonds with the central magnesium atom (keto-C = O...Mg). Hydroxyl groups interact coordinately with magnesium and simultaneously form hydrogen bonds with pyrrol nitrogen. In contrast to chlorophyll a and bacteriochlorophyll a, water molecules in the case of bacteriochlorophyll c do not participate in the intermolecular bond formation in the course of long-wave aggregated forms production. The thermostability of bacteriochlorophyll c aggregates and their rather high stability to desaggregating agents is related to the mentioned peculiarities of their structure. Bacteriopheophytin c in any state (solution or solid film) is not capable to form intermolecular bonds by its carbonyl groups and long-wave aggregates. The specific features of the assemblage of bacteriochlorophyll c aggregates modelling antenna of the green photosynthetic bacteria are discussed.
Mol Biol (Mosk)
PMID:[Molecular mechanism of self-assembly of aggregated bacteriochlorophyll c]. 46 Feb 4

A novel 35S-labeled dihydropyridine (DHP), 1,4-dihydro-2,6-dimethyl-4-(2-trifluoromethylphenyl)-pyridine-3,5-dic arboxyl-3- [2-(N-tert-butoxycarbonyl-L-[35S]methionyl)-aminoethyl]-ester-5-ethyl ester, ([35S]sadopine) (800-1400 Ci/mmol), the respective (+)- and (-)-diastereomers, and unlabeled (+/- )-, (-)-, and (+)-sadopine were synthesized. [35S]Sadopine is an excellent high affinity, high specific activity radioligand to label selectively the DHP receptor of L-type Ca2+ channels in tissue sections as well as in membrane fragments. Both diastereomers bind to the DHP receptors in a saturable and reversible manner, with equal, subnanomolar, dissociation constants. Despite their similar affinities, (+)- and (-)-sadopine differ with respect to their kinetic properties [the association and dissociation rate constants are 10-fold higher for (+)-[35S]sadopine at 22 degrees] and their allosteric modulation of the phenylaklylamine or benzothiazepine binding domain. (+)-Sadopine is a negative but (-)-sadopine a positive allosteric modulator of (-)-[N-methyl-3H]LU49888 or (+)-cis-[3H] diltiazem binding at 30 degrees. Both diastereomers act as L-type Ca2+ channel blockers in cardiac and smooth muscle cells. Computer-based analysis of the electrostatic potentials of the two diastereomers and calculation of the interaction energies with a hypothetical DHP receptor model predicted not only the similar affinities of (+)- and (-)-sadopine but also their Ca2+ channel-blocking effects. The temperature-dependent allosteric differences between the diastereomers suggest that two distinct conformational states of the DHP receptor are stabilized in vitro, both corresponding to a nonconducting state of the channel. Our data indicate that access to the DHP receptor site, but not binding affinity, is a function of the opposite stereochemistry of the sadopine diastereomers. Therefore, labeled and unlabeled (+)- and (-)-sadopine will be useful probes to further characterize the molecular basis of DHP-Ca2+ channel interaction and the pharmacological and physiological significance of the different allosteric conformations of the channel induced by Ca2+ channel-active drugs.
Mol Pharmacol 1992 Feb
PMID:[35S]sadopine, a novel high affinity, high specific activity, L-type Ca2+ channel probe: characterization of two equipotent diastereomers with opposite allosteric properties. 131 9

The gene encoding the streptococcal flavoprotein NADH oxidase (NOXase), which catalyzes the four-electron reduction of O2-->2H2O, has been cloned and sequenced from the genome of Streptococcus (Enterococcus) faecalis 10C1 (ATCC 11700). The deduced NOXase protein sequence corresponds to a molecular mass of 48.9 kDa and contains three previously sequenced cysteinyl peptides obtained with the purified enzyme. In Escherichia coli, the expressed nox gene produced a catalytically active product, which retained its immunoreactivity to affinity-purified NOXase antisera. Alignment of the NOXase protein sequence with that of streptococcal NADH peroxidase (NPXase) revealed that the proteins are 44% identical. Among the most highly conserved segments is a sequence containing Cys42; this residue is known to exist as a stabilized cysteine-sulfenic acid (Cys-SOH) in NPXase and serves as the non-flavin redox center. In addition, three previously identified NPXase segments, known to be involved in FAD and NAD(P)-binding in other pyridine nucleotide-linked flavoprotein oxidoreductases, are strongly conserved in NOXase. Overall, the extensive homology observed between NOXase and NPXase suggests that the monomer chain fold of the oxidase closely resembles that of the peroxidase. Both sequences share limited but significant homology to those of glutathione reductase and other members of the flavoprotein disulfide reductase family. These and other considerations suggest that these two unusual streptococcal flavoproteins constitute a distinct class of FAD-dependent oxidoreductases, the flavoprotein peroxide reductases, easily contrasted with enzymes such as glutathione reductase and thioredoxin reductase.
J Mol Biol 1992 Oct 05
PMID:Molecular cloning and analysis of the gene encoding the NADH oxidase from Streptococcus faecalis 10C1. Comparison with NADH peroxidase and the flavoprotein disulfide reductases. 140 82

Previous studies showed that S-(1,2-dichlorovinyl)-L-cysteine perturbs intracellular Ca2+ homeostasis [Vamvakas et al., Mol Pharmacol 38: 455-461, 1990]. The objective of the present study was to investigate the cellular events that precede and that follow S-(1,2-dichlorovinyl)-L-cysteine-induced mitochondrial Ca2+ release. In incubations with isolated kidney mitochondria, S-(1,2-dichlorovinyl)-L-cysteine-induced Ca2+ efflux is preceded by increased oxidation of mitochondrial pyridine nucleotides and is prevented by ATP, an inhibitor of the hydrolysis of pyridine nucleotides, and by meta-iodobenzylguanidine, an acceptor of ADP-ribose moieties. In LLC-PK1 cells, elevation in the cytosolic Ca2+ concentration is followed by a several-fold increase in DNA double-strand breaks which is attributed to the activation of Ca2+- and Mg(2+)-dependent endonucleases. The formation of DNA double-strand breaks is followed by increased poly(ADP-ribosylation) of nuclear proteins. S-(1,2-Dichlorovinyl)-L-cysteine-induced cytotoxicity in LLC-PK1 cells is blocked by chelation of cytosolic Ca2+ with Quin-2, by inhibition of DNA fragmentation with aurintricarboxylic acid and by inhibition of increased poly(ADP-ribosyl)transferase activity by 3-aminobenzamide. These findings indicate that S-(1,2-dichlorovinyl)-L-cysteine bioactivation in renal cells may initiate the following cascade of events: increased oxidation and hydrolysis of mitochondrial pyridine nucleotides resulting in the modification of mitochondrial membrane proteins by pyridine nucleotide-derived ADP-ribose moieties, followed by Ca2+ release. Elevated Ca2+ concentrations may activate Ca(2+)-dependent endonucleases, which leads to DNA fragmentation followed by increased poly(ADP-ribosylation) of nuclear proteins and, finally, cytotoxicity.
 ...
PMID:Events that precede and that follow S-(1,2-dichlorovinyl)-L-cysteine-induced release of mitochondrial Ca2+ and their association with cytotoxicity to renal cells. 141 36


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