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

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

In binar mixture of solvents (dioxane--water, 1 : 4) the spectral-luminescent investigation of the regularities of mixed association and the energetic interaction between molecules of bacteriochlorophyll (BChl) and its analogs (chlorophyll a--Chl, protochlorophyll--PChl, 4-vinyl-protochlorophyll--4VPChl) under variation of donor-acceptor ratio (0,001 less than or equal to CD/CA less than or equal to 1) in the polymer complex was conducted. The essential role of the elementary cell structure of the mixed associate was discovered: the associate of individual BChl did not possess measurable fluorescence whereas the introduction of PChl, 4VPChl and Chl admixture (approximately greater than 1%) into BChl aggregate resulted in the appearance of a BChl fluorescent ability. It was suggested that admixture and BChl molecules formed dimer cells in which the excitation nonradiative deactivation probability was strongly decreased in comparison with individual BChl aggregate. These cells are the centres of mixed associates emission. It was shown that under conditions of effective energy migration in the system of nearly arranged centres with a high degree of orientation the excitation trapping probability strongly depended on the resonance conditions for transition density--transition density interaction between partners of aggregation.
Mol Biol (Mosk)
PMID:[Mixed aggregation of pigments with participation of bacteriochlorophyll]. 47 Sep 44

The aggregated forms of protochlorophyll a (PChl), 4-vinyl-protochlorophyll a (4VPChl) and chlorophyll a (Chl) in binar mixtures of dioxane-water was investigated. The aggregates are oligomer particles of pigment molecules having considerable degrees of fluorescence polarisation which points to their ordered structure. Two types of fluorescent associates I and II have been discovered. By its electronic spectrum I is similar to the molecular pigment but has smaller quantum yield B congruent to 10(-2) and the lifetime of fluorescence tau congruent to 3--4.10(-9) sec. Associates of type I spontaneously transform into associates of type II which have narrower bands of electronic spectrum than the monomer, very low B congruent to 10(-3)--10(-4) and tau congruent to 2--4.10(-10) sec. In contrast with the decreasing of B and the band intensities in CD spectrum conditioned by rotational strength increase by factor of 100 under transformation from I to II. It follows from these data that the antibatic connection possibly exists between excitation deactivation in associates and their optical activity. From data on splitting the associate CD spectra of type I and II the excitation interaction energy V12 congruent to 75 cm-1 was estimated. The reasons of increasing of rotational strength under transformation from I to II and the overturn of the sign dependence of bands in CD spectrum in some cases are discussed.
Mol Biol (Mosk)
PMID:[Spectral-luminescent properties of separate aggregated forms of pigments in solutions]. 73 87

The addition of water to dioxane solution of protochlorophyll (PChl) and 4-vinyl-protochlorophyll (4VPChl) results in a number of transformations related with pigment molecule associations into polymer formations and with their conversion. By variation of pigment concentration and composition of binar mixture of solvents a set of aggregated forms with different electronic spectra can be obtained. At the first stage the monomeric pigment converts into polymer with long-wavelenght absorption maximum of 633 nm (P633). During 1-3 hours P633 converts into other aggregated forms: either P639 or P645 depending on the proportion of dioxane and water. The pigment aggregates are characterized by fluorescence (quantum yield less than or equal to 1%) with maxima close to the main maxima of absorption spectra. Alongside with the main aggregated forms of PChl and 4VPChl the presence of a small number of longer-wavelength aggregates in solutions is established by fluorescence spectra. The investigation of dependence of fluorescence spectra on excitation wavelength, as well as of fluorescence excitation spectra of pigments in binary mixture shows that the long-wavelength aggregates can form part of complex associate and be effective trapping centres of electronic excitation of shorter wavelength aggregated forms. The phenomenon of 4VPChl association in concentrated solutions of castor oil (c greater than-10(-2) m/l) is discovered, which is especially marked after a long storage of the solutions at lower temperature (t=-2 degrees C). Under these conditions the two aggregated forms P640 and P650 alongside with monomer are present. The aggregate P650 is characterized by fluorescence with maximum of 655 nm and spectrally similar to the natural form of photoactive protochlorophyll. The experimental data show that the protochlorophyll pigments form a set of aggregated forms and that the medium conditions favour the predominance of some of the forms and their interconversion. The results obtained evidence that the main reason of the long-wavelength shift of electronic spectra for PChl natural forms is the intermolecular interaction related with the association of pigment monomeric molecules.
Mol Biol (Mosk)
PMID:[Aggregation of 4-vinyl-protochlerophyll and protochlorophyll in solutions]. 94 May 52

Localization of the activity of both the dehydrogenase and oxidase forms of xanthine oxidoreductase were studied in biopsy and postmortem specimens of various human tissues with a recently developed histochemical method using unfixed cryostat sections, poly-(vinyl alcohol) as tissue stabilizator, 1-methoxyphenazine methosulphate as intermediate electron acceptor and Tetranitro BT as final electron acceptor. High enzyme activity was found only in the liver and jejunum, whereas all the other organs studied showed no activity. In the liver, enzyme activity was found in sinusoidal cells and both in periportal and pericentral hepatocytes. In the jejunum, enterocytes and goblet cells, as well as the lamina propria beneath the basement membrane showed activity. The oxidase activity and total dehydrogenase and oxidase activity of xanthine oxidoreductase, as determined biochemically, were found in the liver and jejunum, but not in the kidney and spleen. This confirmed the histochemical results for these organs. Autolytic rat livers several hours after death were studied to exclude artefacts due to postmortem changes in the human material. These showed loss of activity both histochemically and biochemically. However, the percentage activity of xanthine oxidase did not change significantly in these livers compared with controls. The findings are discussed with respect to the possible function of the enzyme. Furthermore, the low conversion rate of xanthine dehydrogenase into xanthine oxidase during autolysis is discussed in relation to ischemia-reperfusion injury.
Virchows Arch B Cell Pathol Incl Mol Pathol 1992
PMID:Distribution of xanthine oxidoreductase activity in human tissues--a histochemical and biochemical study. 136 18

Acrylamide (AA) has been reported to induce dominant lethal mutations in male rat germ cells and tumors in a variety of organs, including the scrotum, thyroid and mammary glands, but not the liver of rats. The structurally similar vinyl monomer acrylonitrile (ACN) does not induce dominant lethal mutations but does induce tumors of the brain, Zymbal gland, forestomach and mammary gland, but not the liver of rats. Several in vitro and/or in vivo unscheduled DNA synthesis (UDS) assays were employed to examine the potential tissue-specific genotoxic activity of these compounds. Neither AA nor ACN induced DNA repair in either the in vitro or in vivo hepatocyte DNA repair assays. Glycidamide (GA), a mutagenic metabolite of AA, induced DNA repair in the in vitro hepatocyte DNA repair assay. Cyanoethylene oxide (CEO), a mutagenic metabolite of ACN, did not yield a DNA repair response in the in vitro hepatocyte DNA repair assay, but was highly toxic and could not be tested at doses equivalent to GA. AA, but not ACN, produced a DNA repair response in the in vivo spermatocyte DNA repair assay. AA produced a slight response in the in vitro human mammary epithelial cell (HMEC) DNA repair assay in normal cells derived from discarded surgical samples from five different women. GA produced a strong UDS response in all cases in the same assay. CEO, but not its parent compound ACN, produced a response in the HMEC DNA repair assay. These results show a highly tissue-specific pattern of genotoxic activity for AA and ACN that correlates, to the extent that it has been examined, with the tissue-specific pattern of carcinogenic and dominant lethal activity. The induction of DNA repair by GA and CEO confirms the genotoxic potential of these metabolites. While the observation of genotoxic activity of AA in the HMEC DNA repair assay suggests that mammary cells might be a target for carcinogenic activity of this compound in humans, other factors such as pharmacokinetics and epidemiology must be evaluated to establish that effect.
Environ Mol Mutagen 1992
PMID:Tissue-specific genotoxic effects of acrylamide and acrylonitrile. 139 5

The heme vinyl substituents in a shark (Galeorhinus japonicus) myoglobin in its met-cyano form (MbCN) have been characterized by NMR and the results were compared with those of the well-studied sperm whale (Physter catodon) myoglobin. Their orientation has been inferred from NOE connectivities and the analysis of the hyperfine shifts based on the principal magnetic tensor determined by MATDUHM (Magnetic Anisotropy Tensor Orientation Determination Utilizing the Heme Methyls) [Yamamoto, Y., Nanai, N. and Chujo, R.(1990) J. Chem. Soc., Chem. Commun. 1556-1557]. It has been shown that the C3-vinyl group is oriented roughly orthogonal to the heme plane in both G. japonicus and P. catodon MbCNs at 35 degrees C and their C8-vinyl groups, on the other hand, are close to in-plane orientation. Although CO form of myoglobin (MbCO) and MbCN have been thought to be isostructural to each other, the C8-vinyl orientation for P. catodon MbCN is found to be different from the orthogonal orientation indicated in the crystal structure analysis of MbCO [Hanson, J.C. and Schoenborn, B.P. (1981) J. Mol. Biol. 153, 117-146]. Their mobility has been characterized quantitatively from the study of time-dependent NOE build-up between the selected pair of the vinyl proton resonances. It has been revealed that the heme C3- and C8-vinyl groups of approximately 1 mM G. japonicus MbCN at 45 degrees C undergo internal motion with the correlation time of 1.9 and 2.4 ns, respectively. Therefore, their oscillatory motion is faster by a factor of 4-5 compared with the protein overall tumbling. Difference in the internal mobility between the two vinyl groups in the active site of this Mb is attributed to their differential contact with the apo-protein.
 ...
PMID:Orientation and mobility of the heme vinyl groups in myoglobins with the aid of NOE and MATDUHM NMR. 156 83

Peptides derived from prodynorphin and preproenkephalin are located in GABAergic striatal projection neurons. We have used nucleic acid hybridization techniques to investigate the role of GABA in the regulation of striatal opioid peptide gene expression. Rats were treated with the GABA-transaminase inhibitors aminooxy acetic acid, ethanolamine O-sulphate and gamma-vinyl-GABA for one week. The GABA levels in the striatum were significantly elevated after each treatment. The GABA-transaminase-inhibitors decreased the striatal levels of the opioid peptides met-enkephalin and dynorphin(1-8) and concomitantly decreased the concentrations of the mRNAs coding for proenkephalin and prodynorphin. These findings indicate that GABA exerts an inhibitory influence on prodynorphin and proenkephalin gene expression in the striatum. The mechanisms underlying these inhibitions are discussed.
Brain Res Mol Brain Res 1991 Apr
PMID:GABAergic regulation of striatal opioid gene expression. 164 82

The Gunn rat, which is deficient in the UDP-glucuronosyltransferase for bilirubin, promptly excreted polar conjugates of the dimethyl ester of bilirubin in bile after intravenous infusion of this ester. The conjugates proved to be monoglutathione thioether adducts of the vinyl groups of the parent tetrapyrrole. High performance liquid chromatographic analysis of the conjugates as their dipyrrolic azosulfanilates demonstrated that only one of the dipyrroles of each tetrapyrrole was conjugated. The nonconjugated dipyrrole eluted as either the methyl endo- or exovinyl azodipyrrole. The amino acid composition of the pigments was consistent with that of a monoglutathione conjugate. NMR spectroscopy of the two major pigments demonstrated the loss of the proton signals of the C-18 vinyl group, indicating it to be the site of conjugation. Cation fast atomic bombardment tandem mass spectrometry demonstrated a molecular ion, [M + H]+, of m/z 937, which fragmented with a loss of 307 atomic mass units, consistent with glutathione. A molecular ion of m/z 807 was observed for the conjugate treated with gamma-glutamyltranspeptidase, consistent with the loss of glutamate. The mass spectrometry data indicated that the conjugates also contained a functional group whose mass was equivalent to hydroxyl, suggesting initial formation of an epoxide, which then reacts with glutathione. Pretreatment of the rat with 2,3,7,8-tetrachlorodibenzo-p-dioxin to induce cytochrome P-450 resulted in a 6-fold increase of the biliary excretion of the glutathione conjugates. Such induction also resulted in the excretion of a glutathione conjugate of bilirubin itself.
Mol Pharmacol 1991 Oct
PMID:Identification of glutathione conjugates of the dimethyl ester of bilirubin in the bile of Gunn rats. 168 18

Point mutations of c-ras genes were investigated in human angiosarcomas of the liver associated with occupational exposure to vinyl chloride. DNA prepared from either frozen or paraffin-embedded tissues was amplified by the polymerase chain reaction, and putative point mutations at codons 12, 13, and 61 of c-Ha-ras, c-Ki-ras, and N-ras were analyzed by dot-blot hybridization with allele-specific oligonucleotides. A G.C----A.T transition in the second nucleotide at codon 13 of the c-Ki-ras-2 gene was detected in 5 of 6 tumors. This mutation is likely a consequence of vinyl chloride-DNA adduct formation. It leads to the substitution of glycine by aspartic acid in the resulting p21 protein, a consistent amino acid substitution found so far in all types of human cancer exhibiting a codon 13-mutated Ki-ras gene.
Mol Carcinog 1991
PMID:Activation of Ki-ras gene by point mutation in human liver angiosarcoma associated with vinyl chloride exposure. 179 83


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