Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.6.99.3 (diaphorase)
 5,903 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A gene of the chloroplast genome has been designated the psbG gene on the basis that in maize the gene product is a 24-kDa polypeptide of photosystem two (PS2) (Steinmetz, A. A., Castroviejo, M., Sayre, R. T., and Bogorad, L. (1986) J. Biol. Chem. 261, 2485-2488). We have located and sequenced the equivalent gene in wheat (Triticum aestivum) and have raised specific antibodies to the gene product following its expression in Escherichia coli as a beta-galactosidase fusion protein. Using these antibodies, we have investigated the location of the gene product in various thylakoid membrane fractions of pea (Pisum sativum). The gene product of apparent molecular mass 27-28 kDa is severely depleted in PS2-enriched membrane preparations and its distribution between stromal and granal regions of the membrane is distinct to that of the psbC gene product which is known to be a core polypeptide of PS2. We therefore conclude that psbG does not code for a component of PS2 but instead suggest that it is present in a novel protein complex of the thylakoid membrane. On the basis of 1) the conserved overlap between psbG and ndhC, a chloroplast gene which shows significant homology to a mitochondrial gene that codes for a subunit of the NADH-ubiquinone oxidoreductase of mitochondria, and 2) sequence similarity between the psbG gene product and the ndh gene product of E. coli, which codes for a respiratory NADH dehydrogenase, we propose that this ill-defined complex functions as a NADH or NADPH-plastoquinone oxidoreductase.
 ...
PMID:psbG is not a photosystem two gene but may be an ndh gene. 266 82

Assimilatory NADH:nitrate reductase from Chlorella is a homotetramer which contains one of each of the prosthetic groups FAD, heme, and Mo6+ per 100-kDa subunit. At low protein concentrations, this tetramer dissociates to a fully active dimer. To further elucidate the possible relationship between quaternary structure and activity, the functional size of nitrate reductase was determined by radiation inactivation analysis at high and low concentrations of enzyme where the principal physical species would be either tetrameric or dimeric, respectively. In both cases, the size obtained by this method was 100 kDa, suggesting that each subunit in the tetramer or dimer can function independently. These results confirm earlier results which indicated that the subunits are identical and that each contains a full complement of prosthetic groups. We also found that the functional sizes of the partial activities NADH:cytochrome c reductase, NADH:ferricyanide reductase, and reduced methyl viologen:nitrate reductase were fractions (approximately 58 kDa, 47 kDa, and 28 kDa, respectively) of the subunit molecular mass, suggesting that these domains are functionally independent.
 ...
PMID:Radiation inactivation of assimilatory NADH:nitrate reductase from Chlorella. Catalytic and physical sizes of functional units. 351 Feb 7

Electrophoresis of a Corynebacterium glutamicum membrane preparation in the presence of sodium dodecyl sulfate, followed by staining for peroxidase activity (heme staining), showed only one band at about 28 kDa. This 28 kDa protein was purified from C. glutamicum membranes by chromatography in the presence of decylglucoside using DEAE-Toyopearl and hydroxylapatite columns, as the sole c-type cytochrome in the bacterium. The cytochrome showed an alpha band at 551 nm, and its E(m, 7) was about 210 mV. A QcrCAB operon encoding the subunits of a putative quinol cytochrome c reductase was found 3'-downstream of ctaE encoding subunit III of cytochrome aa(3) in the C. glutamicum genome. The deduced amino acid sequence of qcrC, composed of 283 amino acid residues, contained two heme C-binding motifs and was in agreement with partial peptide sequences obtained from the 28 kDa protein after V8 protease digestion. We propose to name this protein cytochrome cc. The presence of cytochrome cc is a common feature of high G+C content Gram-positive bacteria, since we could confirm this protein by electrophoresis; homologous QcrCAB operons are also known in Mycobacterium and Streptomyces. QcrA and qcrB of C. glutamicum encode the Rieske Fe-S protein and cytochrome b, respectively, although these proteins were not co-purified with cytochrome cc. The phylogenetic tree of cytochromes b and b(6) show that C. glutamicum cytochrome b, along with those of other bacteria in the high G+C group, is rather different from the Bacillus counterparts, but highly similar to the Deinococci and Thermus cytochromes. This indicates that there is a fourth group of bacteria in addition to the three clades: proteobacterial cytochrome b, cyanobacterial b(6) and green sulfur-low G+C Gram-positive bacteria.
 ...
PMID:A novel hydrophobic diheme c-type cytochrome. Purification from Corynebacterium glutamicum and analysis of the QcrCBA operon encoding three subunit proteins of a putative cytochrome reductase complex. 1111 40