Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.9.3.1 (cytochrome oxidase)
 8,822 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Highly active, essentially homogeneous, preparations of ferrocytochrome c oxidase (EC 1.9.3.1) have been obtained from both yeast and beef heart by extraction with cholate, fractionation with ammonium sulfate, and replacement of cholate by Tween 20. The molecular weights of the resultant proteins equal 260 +/- 23 X 10(3) and 205 +/- 10(3); they contain seven and six different polypeptide subunits, respectively, all in equimolar amounts, with apparent molecular weights of 42.4, 34.1, 24.7, 14.6, 14.6, 12.3, 10.6 X 10(3), and 47.5, 20.4, 14.5, 14.5, 13.0, 11.0 X 10(3), respectively. By means of apolar chromatography on L-leucine coupled to agarose these enzymes can be stripped of their largest subunit(s) resulting in preparations with molecular weights of 170 +/- 17 X 10(3) and 124 +/- 20 X 10(3), and containing only five polypeptides, with the largest remaining one (molecular weight congruent to 20 X 10(3)) present in less than stoichiometric amounts. This interconversion and subunit removal has been monitored by exclusion chromatography, four systems of acrylamide gel electrophoresis--some with the protein labeled with 125I under denaturing conditions--isoelectric focusing, and hydrodynamic methods. It has virtually no effect on heme a and copper content and on the catalytic parameters of the enzymes. We conclude that subunits I and II in enzymes from fungal, and subunit I in those from animal, sources are dispensable for the catalysis of the oxidation of ferrocytochrome c by, and are probably not essential for the attatchment of prosthetic groups to, these proteins.
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PMID:Studies on cytochrome oxidase. Partial resolution of enzymes containing seven or six subunits, from yeast and beef heart, respectively. 0 85

Proton translocation is important in membrane-mediated processes such as ATP-dependent proton pumps, ATP synthesis, bacteriorhodopsin, and cytochrome oxidase function. The fundamental mechanism, however, is poorly understood. To test the theoretical possibility that bundles of hydrophobic alpha-helices could provide a low energy pathway for ion translocation through the lipid bilayer, polyamino acids were incorporated into extruded liposomes and planar lipid membranes, and proton translocation was measured. Liposomes with incorporated long-chain poly-L-alanine or poly-L-leucine were found to have proton permeability coefficients 5 to 7 times greater than control liposomes, whereas short-chain polyamino acids had relatively little effect. Potassium permeability was not increased markedly by any of the polyamino acids tested. Analytical thin layer chromatography measurements of lipid content and a fluorescamine assay for amino acids showed that there were approximately 135 polyleucine or 65 polyalanine molecules associated with each liposome. Fourier transform infrared spectroscopy indicated that a major fraction of the long-chain hydrophobic peptides existed in an alpha-helical conformation. Single-channel recording in both 0.1 N HCl and 0.1 M KCl was also used to determine whether proton-conducting channels formed in planar lipid membranes (phosphatidylcholine/phosphatidylethanolamine, 1:1). Poly-L-leucine and poly-L-alanine in HCl caused a 10- to 30-fold increase in frequency of conductive events compared to that seen in KCl or by the other polyamino acids in either solution. This finding correlates well with the liposome observations in which these two polyamino acids caused the largest increase in membrane proton permeability but had little effect on potassium permeability. Poly-L-leucine was considerably more conductive than poly-L-alanine due primarily to larger event amplitudes and, to a lesser extent, a higher event frequency. Poly-L-leucine caused two populations of conductive events, one in the 0.1-0.5 pA range, and one in the 1.0-5.0 pA range, whereas nearly all events caused by poly-L-alanine were in the 0.1-0.5 pA range at an applied voltage of +60 mV. The channel-like activity appeared to switch between conductive and nonconductive states, with most open-times in the range of 50-200 ms. We conclude that hydrophobic polyamino acids produce proton-conducting defects in lipid bilayers that may be used to model functional proton channels in biological membranes.
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PMID:Alpha-helical hydrophobic polypeptides form proton-selective channels in lipid bilayers. 752 Feb 89

Enteropathogenic Campylobacterjejuni, C. coli and C. lari are currently the most common causes of acute infectious diarrhoeal illness in the UK. Many domestic animals, including pigs, act as natural reservoirs of these organisms and infection may occur through the ingestion of contaminated foodstuffs. C jejuni and C. coli, isolated from the livers of bacon pigs, were examined at subspecies level by multilocus enzyme electrophoresis (MEE) typing with seven enzymic loci. Polymorphological variation was highest with indophenol oxidase, isocitrate dehydrogenase and L-phenylalanyl-L-leucine peptidase giving 5. 5 and 4 alleles at these loci, respectively. The 35 Campylobacter isolates examined in this study (12 C. jejuni and 23 C coli) represented 30 unique electrophoretic types (ETs). Of these ETs, 8 unique types were detected for the 12 C jejuni isolates and 19 unique ETs were detected for the 23 C coli isolates. In addition, 3 types (ETs 2, 5, 10) were shared in common among C. jejuni and C coli. The average number of alleles per enzyme locus was 3.28. The mean genetic diversity, i.e. arithmetic average over all loci assayed, including monomorphic values, was 0.5573 and 0.5350 for C jejuni and C coli. respectively. Alleles were shared by C jejuni and C coli, suggesting an exchange of genetic material between the species. MEE analyses of isolates showed that there was a wide range of subspecies types within both C. jejuni and C coli in porcine livers. In certain cases, up to four phenotypically different strains of C coli were isolated from one liver, indicating multiple infections.
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PMID:Subspecies characterization of porcine Campylobacter coli and Campylobacter jejuni by multilocus enzyme electrophoresis typing. 1186 82