Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Comparisons of the amino acid compositions of the nitrogenase proteins from different organisms and their correlation with cross-reactivities and taxonomical data suggest an evolution within bacterial genomes rather than within plasmids. Comparisons of the amino acid compositions of nitrogenases and other ATP-ases show similarities which might be due to the evolution of these ATP-ases from a common ancestral protein.
J Mol Evol 1976 Mar 29
PMID:Possible evolutionary relationships of the nitrogenase proteins. 13 Dec

The interaction of nitrogenase with spin labels of four types have been studied. Conclusion about the presence of two SH-groups in the nitrogenase active site (one in Mo-Fe-protein and one in the Fe-protein) have been drawn from the correlation between the degree of inhibition of nitrogenfixing activity by the labels derived from p-Cl-Hg-benzoate and degree of binding of these labels to the nitrogenase molecule. Anaysis of EPR spectra of spin-labeled nitrogenase at 77 degrees K and at room temperature have shown that the labels bind to the free SH-groups and interact with iron containing center (ICC) of nitrogenase through the exchange mechanism. Distance between SH-group and ICC have been found to be 12 A. Spin labels derived from isocyanide have been bound directly to ICC in amount of 6--10 labels per one nitrogenase molecule. Due to the exchange interaction between these labels they give the singlet ESR spectra both at 77 degrees and at room temperature which is characteristic for the closely disposed labels. From this fact a conclusion have been drawn about the cluster structure of ICC. The labels derived from iodoacetamide ana maleimide bind SH- and NH2-groups of nitrogenase molecules. Analysis of temperature dependence of the effective rotational frequency of this labels have revealed a conformational transition in nitrogenase molecule at 19 degrees C, that has made it possible to explain the break in the Arrenius plots of enzyme activity.
Mol Biol (Mosk)
PMID:[Study of the nitrogenase from Azotobacter vinelandii by the method of spin labels]. 17 70

The sensitivity of the molybdenum-iron(MoFe)-protein of Clostridium pasteurianum nitrogenase toward oxidation has been studied by determining the enzymatic activity of this component after incubating it anaerobically in ferricyanide solutions of various oxidizing strengths (as measured by their oxidation potentials). It was found that the MoFe-protein remains active at potentials up to +350 mV (vs. standard hydrogen electrode) but becomes readily inactivated at more oxidizing potentials, after a lag period, depending on the potential level and temperature. Oxidative inactivation by ferricyanide results in the release of most of the Mo, Fe and S atoms from the protein which causes the loss of the absorption bands in the visible region. The metals and sulfur could be re-incorporated by incubation in a mixture containing thiol, sulfide, molybdate, and ferric iron. The EPR spectrum of the oxidatively inactivated MoFe-protein showed that both the high- and low-field signals are readily affected. Re-incorporation of the metals and sulfur into the "bleached" protein produced an EPR spectrum similar to that of the air-inactivated protein. Incubation of the Mo-Fe-protein with mersalyl abolished its enzymic activity. The difference spectrum before and after mersalyl treatment resembles that of the soluble spinach ferredoxin.
Mol Cell Biochem 1979 Jul 31
PMID:Oxidative inactivation of the molybdenum-iron-protein component of nitrogenase from clostridium pasteurianum. 22 73

A series of mutants defective in nitrogen fixation (nif) were isolated in Klebsiella pneumoniae strain M5a1. The nif mutations were either located on plasmid pRD1 or on the K. pneumoniae chromosome. A total of 37 plasmid mutants and 28 chromosomal mutants were employed in complementation tests using the acetylene reduction technique. Most mutants could be assigned to one of seven nif cistrons: nifA, nifB, nifD, nifE, nifF, nifH, and nifK. Complementation analysis of two nif deletion mutants confirmed transductional evidence that these strains carry nifB-A-F deletions. One deletion mutant had, in contrast to previous transductional analysis, a functional nifK cistron and presumably is deleted for nifB-A-F-E. Examination of the biochemical phenotype of several mutants suggests that the nifA product has a regulatory function, and nifK, nifD and nifH are most probably the structural genes for nitrogenase.
Mol Gen Genet 1977 Nov 29
PMID:Complementation analysis of Klebsiella pneumoniae mutants defective in nitrogen fixation. 34 Sep 23

Three new genes nifM, nifI and nifN have been mapped in the nif gene cluster of Klebsiella pneumoniae and a fourth gene nifJ has been confirmed as being a separate cistron. Polar nif mutations were obtained by transposition of Tn7 to plasmid pRD1, and of Tn5 and Tn10 to plasmid pMF100, a derivative of pRD1. Complementation analysis of the nif::Tn mutants led to the identification of at least six transcriptional units: nifB; nifA; nifJ; nifH, nifD and nifK; nifE and nifI; nifN, nifM and nifF. Biochemical and genetic evidence suggest that the three genes nifH, nifD and nifK, which are probably the structural genes for nitrogenase, belong to the same operon and are transcribed from nifH to nifK. A polypeptide with a molecular weight of approximately 120,000 is presumed to be the nifJ product.
Mol Gen Genet 1978 Sep 20
PMID:Polarity of mutations induced by insertion of transposons Tn5, Tn7 and Tn10 into the nif gene cluster of Klebsiella pneumoniae. 36 60

Polar mutations were obtained by integration of bacteriophage Mu c+ or Mu cts DNA into the Klebsiella pneumoniae nif genes located on plasmid pCE1, a derivative of pRD1. In addition, nif deletions were isolated from nif::Mu cts plasmids. Complementation data allowed the characterization of twelve nif cistrons, nine corresponding to previously identified genes. Polar effect of Mu DNA insertions suggested the existence of at least six transcription units: 1) nif K, nif D and nif H--2)nif A and nif L--3) nif E and a new gene--4) nif B--5) nif F--6) nif J. Nif K, nif D and nif H, which are most probably the structural genes for nitrogenase, seem to belong to the same operon transcribed from nif H to nif K. This was confirmed by SDS gel autoradiography of pulse labelled proteins. Moreover it was possible to identify, on the autoradiograms, a polypeptide which likely is the product of nif J and whose biosynthesis is under the control of nif A.
Mol Gen Genet 1978 Oct 04
PMID:Genetic and biochemical analysis of mutants induced by bacteriophage Mu DNA integration into Klebsiella pneumoniae nitrogen fixation genes. 36 77

A HindIII (17.0 kb) and an EcoR1 restriction fragment (6.9 kb) of Klebsiella pneumoniae nif DNA were cloned on two small amplifiable plasmids, pCM1 and pSA30 respectively. These plasmids between them carry 14 of the 15 known Klebsiella nif genes. The operon for the three structural genes for nitrogenase, nifpHDK, is carried on pSA30: four and five of the remaining six operons are on pCRA37 and pCM1 respectively. All of the nif genes were assigned to endonuclease restriction fragments of DNA using the Southern blotting technique (Southern, 1975) with total DNA of nif insertion mutants and radioactive plasmid DNA which contained cloned nif DNA sequences. Their locations were consistent with the genetic map of nif genes. The estimated size of the nif gene cluster was 24 kb.
Mol Gen Genet 1979 Jul 02
PMID:Overlapping sequences of Klebsiella pneumoniae nifDNA cloned and characterized. 38 62

The dependence of the nitrogen reduction rate on N2-concentration under high nitrogen pressures was measured. The reason for the sharp break of the Arrenius curves in nitrogenase reactions at 20 degrees C was examined. The influence of nitrogen on isotope effect catalyzed by nitrogenase was studied. The kinetic schemes that explain the peculiarities of the nitrogenase reactions were analyzed by the graph's theory. On the base of new conception of inhibitor-"interceptor" of electrons the literature data were discussed.
Mol Biol (Mosk)
PMID:[Several kinetic features of nitrogenase reactions]. 44 Mar 7

The electronic-conformational interactions (ECI) of enzyme-substrate complexes are treated with the help of the method of intermolecular orbitals. The applicability of this approach is shown concerning some problems, related to ECI. The activation of N2 in the active site of nitrogenase, the proton transfer in the system, containing hydrogen bonds, and the modelling of the initial state of the reaction of lysozyme with oligosaccharides were examined.
Mol Biol (Mosk)
PMID:[Electronic-conformational interactions of molecular-biological systems. II. Study of the enzyme-substrate complex with the help of qualitative methods of quantum chemistry]. 46 Jan 99

Nitrogenase molecules are observed in electron micrographs as hepta or octa hedral rings about 100 angstrom in diameter and stick-like particle 95 angstrom wide and as long as 300 angstrom and more. The electron microscopy pattern was investigated by the optical diffraction technique. It is shown that the nitrogenase molecule has a cylindrical helical structure. The helical parameters of this structure have been determined. The molecule is composed of a family of discrete helixes (number of helixes 8), the spacing between the nearest subunits along the vertical axis being 25 angstrom and the period of the structure about 50 angstrom. It is supposed that the stick-like particle as a side-view projection of the polymerized round molecules. A hypothetic model of the protein is presented.
Mol Biol (Mosk)
PMID:[Investigation of the structure of nitrogenase by means of electron microscopy combined with optical diffraction]. 105 41


1 2 3 4 5 6 7 8 9 10 Next >>