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

Three forms (E1, E2 and E3) of leucyl-tRNA synthetase (LeuRS) were separated by DEAE-cellulose chromatography of total aminoacyl-tRNA synthetases from cow lactating mammary gland. The method of purification of all three components is described. E1 is a dimeric molecule (alpha 2) of molecular weight 182 000. Two other forms of molecular weight 67 000 and 64,000 consist of a single polypeptide chain as determined by polyacrylamide gel electrophoresis. Optimum conditions and kinetic parameters of leucyl-tRNA formation were studied for every enzyme form. The low values of Vmax and thermostability are characteristic of E3. All forms of LeuRS interact with 6 isoaccepting tRNA(Leu) from lactating mammary gland and can activate leucine in the absence of tRNA. E2 and E3 are supposed to derive from the native enzyme by endogenous proteolysis. The physico-chemical properties of native LeuRS from lactating mammary gland are compared with those of LeuRS's from other sources.
Mol Biol (Mosk)
PMID:[Purification and properties of leucyl-tRNA synthetase from the cow mammary gland]. 57 75

A study of physico-chemical properties of the nucleic acid of phage Brevibacterium flavum was made. It was found that the phage nucleic acid is a double-stranded DNA. The content of GC pairs was determined by the temperature of DNA melting and by the chromatographic method. In both cases it was (52 +/- 2) mole %. It has been shown that endonuclease Eco RI treatment of phiB DNA forms 12 fragments. The molecular weight of phiB DNA has been determined by two independent methods: by measuring the contous length of DNA and by the sum of molecular weights of DNA restricts obtained after hydrolysis by endonuclease Eco RI and was found to be (30 +/- 1) . 10(6) dalton. Electron microscopy investigations detected rod and circular DNA in either monomeric or dimeric forms. The polarity of DNA arrangement in the phiB phage particle was determined by using the partial denaturation maps.
Mol Biol (Mosk)
PMID:[Physico-chemical study of the nucleic acid of bacteriophage phiB]. 65 78

Sakakibara and Tomizawa (1974a) have described a soluble in vitro system that can carry the semi-conservative replication of the Co1 E1 plasmid. However, the usefulness of this system is restricted by its rapid inactivation during storage. This paper describes a stable soluble system prepared by freeze-thaw lysis of chloramphenicol-treated E. coli cells which replicates added Co1 E1 and C1o DF13 DNA. It differs from the system employed by Sakakibara and Tomizawa in two important points: (1) Its replicative capacity for Co1 E1 DNA is by an order of magnitude higher and (2) it can be stored in liquid nitrogen for several months without loss of activity Plasmid replication in vitro is dependent of DNA polymerase I and requires de novo RNA synthesis. It is completely inhibited by rifampicin, oxolinic acid, and novobiocin. The DNA synthesized during a 60 min incubation at 30 degrees C consists mostly of monomeric supercoils. If Co1 E1 DNA is used as template, a minor portion of the label is also found in closed dimeric catenanes. Density labelling experiments indicate that plasmid DNA synthesis occurs by a semi-conservative replication process.
Mol Gen Genet 1976 Jun 15
PMID:Replication of small plasmids in extracts of Escherichia coli. 78 16

(1) Two viper cells lines were investigated, one which harbors IMV in the mitochondria (VSW cells) and one without detectable IMV (VH3 cells). (2) The size of closed circular mtDNA molecules from both VSW and VH3 cells was found to be significantly greater (5.4 to 5.6 micron) than the contour lengths of typical mammalian cells (4.8 to 5.2 micron). (3) A small percentage of mini-circles ranging in size from 0.1 to 0.6 micron was observed to band with closed circular mtDNA from both cell lines. Minicircles were especially abundant in VH3 cells. (4) MtDNA from VSW cells contained 34.1% dimers plus oligomers (10.2% oligomers), whereas VH3 cells had only 14.8% dimeric and oligomeric forms (5.4% oligomers). (5) Treatment of VSW cells with 1 microng/ml ethidium bromide for 48 hours resulted in an increased incidence of IMV (IMV in 15% of mitochondrial sections) as compared with untreated VSW cells (IMV in 3% of mitochondrial sections).
Mol Cell Biochem 1977 Feb 04
PMID:Studies of mitochondria and mitochondrial DNA extracted from organelles harboring an intramitochondrial virus. 85 28

Cytoplasmic microtubules, plane monolayers of tubulin filaments and single filaments have been investigated by electron microscopy. The methods of optical diffraction, filtering and three-dimensional reconstruction have been used to analyse the micrographs and to construct a model of the dimeric molecule of tubulin. When viewed in the direction perpendicular to the longitudinal axes the molecule bear resemblance to the figure "8". When rotated by 90 degrees it looks as if composed of two globules. Two variants of the quoternary structure are considered: 1) each of two subunits is a deformed ring; 2) each rings of the "8"-like particles consists of two halves of different subunits. The second protein layer which is formed on microtubules in the presence of protamine consists of tubulin and is characterized by the crystal lattice similar to that of the microtubule itself, but rotated through the angle of about 95 degrees. In the presence of protamine we also detected flat spirals and stacks of such spirals forming short tubules.
Mol Biol (Mosk)
PMID:[The structure of microtubules]. 94 May 61

The level of two thioesterases, acyl-CoA thioesterase and acyl-ACP thioesterase was determined during seed maturation in oil seed rape. Both thioesterase activities rose markedly prior to the onset of lipid accumulation, but the induction kinetics suggest that the activities reside on distinct polypeptides. Acyl-ACP thioesterase (EC 3.1.2.14) was purified 2000-fold using a combination of ion exchange, ACP-affinity chromatography, chromatofocusing and gel filtration. Using native gel electrophoresis, and assays for enzymic activity, two polypeptides were identified on SDS-PAGE as associated with the activity. Cleveland mapping of these polypeptides, of 38 kDa component and 33 kDa respectively, demonstrated that they are related. An antibody was prepared against the 38 kDa component, and this also recognises the 33 kDa polypeptide in highly purified preparations. Western blotting of a crude extract identifies one band at 38 kDa consistent with the 33 kDa component being a degradation product generated during purification. The native molecule has a M(r) of 70 kDa indicating a dimeric structure. The enzyme has a pH optimum of 9.5 and shows strong preference for oleoyl-ACP as substrate. The intact enzyme has an N-terminus blocked to protein sequencing. We also found that two other polypeptides co-purify with acyl-ACP thioesterase under native conditions. The N-terminal amino-acid sequence of these polypeptides is shown and their possible identity is discussed.
Plant Mol Biol 1992 Dec
PMID:Induction, purification and characterisation of acyl-ACP thioesterase from developing seeds of oil seed rape (Brassica napus). 130 Oct 73

R-state monoclinic P2(1) crystals of phosphorylase have been shown to be catalytically active in the presence of an oligosaccharide primer and glucose-1-phosphate in 0.9 M ammonium sulfate, 10 mM beta-glycerophosphate, 0.5 mM EDTA, and 1 mM dithiothreitol, the medium in which the crystals are grown or equilibrated for crystallographic studies (Barford, D. & Johnson, L.N., 1989, Nature 360, 609-616; Barford, D., Hu, S.-H., & Johnson, L.N., 1991, J. Mol. Biol. 218, 233-260). Kinetic data suggest that the activity of crystalline tetrameric phosphorylase is similar to that determined in solution for the enzyme tetramer. However, large differences were found in the maximal velocities for both oligosaccharide or glucose-1-phosphate substrates between the soluble dimeric and crystalline tetrameric enzyme.
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PMID:Kinetic properties of tetrameric glycogen phosphorylase b in solution and in the crystalline state. 130 91

One of the atrial natriuretic factor (ANF) receptors is a 180 kDa protein (180 kDa mGC) which possesses the extraordinary characteristic of being bifunctional: it is both a receptor and a guanylate cyclase. In addition to the 180 kDa mGC, there exists another 120-130 kDa protein which is also bifunctional and a 120 kDa disulfide-linked dimeric cell surface protein that is an ANF receptor, but is not a part of guanylate cyclase. A fundamental question that needs to be resolved is: Are these three apparently biochemically distinct ANF receptors structurally similar? With the aid of affinity crosslinking techniques, a highly specific antibody to the 180 kDa mGC, and GTP-affinity techniques, we now demonstrate the presence of three immunologically similar proteins in rat adrenal gland and testes. These proteins migrate as 180 kDa, 130 kDa and 65 kDa under denaturing sodium dodecyl sulfate polyacrylamide gel electrophoresis and specifically bind ANF, raising one or more of the following possibilities about their relationships: 1) Degradation of 180 kDa to 130 kDa and 65 kDa occurs during purification; 2) 180 kDa bears a precursor-product relationship with 130 kDa and 65 kDa, suggesting the role of a protease in the processing procedure; 3) these proteins are a result of gene splicing; or 4) they are the products of three separate, but very closely related genes.
Mol Cell Biochem 1992 Jan 15
PMID:Three immunologically similar atrial natriuretic factor receptors. 131 50

An octa-heme cytochrome c3, isolated as a dimeric molecule of about 30 kDa from the anaerobic bacteria Desulfovibro desulfuricans Norway, has been crystallized in a form suitable for atomic resolution X-ray structural investigations. The crystals are trigonal, space group P3(1)21 (or its enantiomorph P3(2)21), with cell dimensions: a = b = 72.9 A c = 62.7 A. The asymmetric unit contains most probably one monomer and a solvent content of about 60%. Under this assumption, the crystallographic 2-fold axis relates the two subunits of the dimer. Diffraction extends to 2.0 A.
J Mol Biol 1992 Dec 05
PMID:Crystallization and preliminary crystallographic study of an octa-heme cytochrome c3 from Desulfovibrio desulfuricans Norway. 133 87

Experimental data are reported on DNA-cleaving activity of the synthetic netropsin analogs consisting of the two N-propylpyrrole carboxamide units linked covalently through two or three glycine residues to a copper-chelating tripeptide glycyl-glycyl-L-histidine. Incubation of DNA restriction fragment and netropsin analog in the presence of ascorbate, hydrogen peroxide and Cu2+ ions resulted in selective cleavage of the DNA at or near the preferred sites for binding of netropsin analog. A similar cleavage pattern is observed after X-ray irradiation of DNA complexes with netropsin analogs tethered with Cu2+ ions. The cleavage patterns are found to be dependent on the length of the connecting chain between the histidine-containing tripeptide and netropsin analog. The netropsin analog containing three glycine residues in the connecting chain, but not the analog with a shorter linker chain, can generate an intense cleavage of one of the two polynucleotide chains at a position corresponding to the presumed binding site for the dimeric ligand species. More than 50% of the total DNA can be cleaved at this position after X-ray irradiation. From analysis of the nucleotide sequences surrounding the preferred cleavage site on several DNA fragments we found that the consensus is 5'-TTTTNCA*AAA-3', where N is an arbitrary nucleotide. The Cu(2+)-mediated cleavage of DNA occurs at the second adenine (indicated by an asterisk) from the 5'-end of the sequence. The greatest cleavage activity is observed when the molar ratio of Cu2+ to the netropsin analog is equal to 0.5. Evidently, the Cu(2+)-ligated and unligated oligopeptide species interacts with each other to form a heterodimer bound to DNA at the cleavage site. To test the validity of this model we have studied the binding of unligated netropsin analog and netropsin analog complexed with Cu2+ ion to a self-complementary oligonucleotide 5'-GCGTTTTGCAAAACGC-3'. It is found that binding of Cu(2+)-ligated netropsin analog to the DNA oligomer preincubated with unligated form of the oligopeptide is a cooperative process for which interactions between the two bound ligands are responsible. The cooperativity parameter is estimated to be on the order of factor 6. Finally, a model is proposed in which a heterodimer stabilized by interligand beta-sheet binds in the minor DNA groove.
Mol Biol (Mosk)
PMID:[Specific DNA cleavage by an analog of netropsin containing a copper(II) chelating peptide Gly-Gly-His]. 133 38


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