title: Molecular organization in bacterial cell membranes. Sulfhydryl groups and disulfide bridges in Streptomyces albus and Escherichia coli K 12 cytoplasmic membranes.
abstract: Plasma membranes from Streptomyces albus had 5.2 mol of sulfhydryl groups and 6 mol of disulfide bridges/50 kg proteins whereas Escherichia coli membranes had 3.4 mol sulfhydryl groups and 4 mol disulfide bridges/50 kg protein. About 66% of the sulfhydryl groups of S. albus membranes and 22% of those of E. coli membranes were readily accessible to titration with 5,5'-dithiobis(2-dinitrobenzoic acid). o-[3 Hydroxymercuri-2-methoxypropyl)-carbamyl]-phenoxyacetic acid (mersalyc acid) and p-chloromercuribenzoate were effective in solubilizing membrane proteins from the two bacteria. Other sulfhydryl group reagents, such as N-ethylmaleimide, iodoacetamide and iodoacetic acid, were less effective. Dithiothreitol affected the dodecylsulphate gel electrophoresis patterns of S. albus membranes and soluble fractions. This effect resulted from the reduction of pre-existing disulfide intramolecular bridges and some interchain disulfide formed during solubilization and/or storage. Dithiothreitol also affected the dodecylsulphate gel electrophoresis patterns of E. coli membranes and their soluble fractions. These results suggest that sulfhydryl groups and disulfide bridges play a role in the structural organization of these prokaryotic membranes.
mesh_terms: D001426:Bacterial Proteins / Q000032:analysis; D001665:Binding Sites; D002462:Cell Membrane / Q000648:ultrastructure*; D003545:Cysteine / Q000032:analysis; D004220:Disulfides / Q000032:analysis; D004228:Dithionitrobenzoic Acid; D004229:Dithiothreitol; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000648:ultrastructure*; D046911:Macromolecular Substances; D011485:Protein Binding; D011487:Protein Conformation; D013302:Streptomyces / Q000648:ultrastructure*; D013438:Sulfhydryl Compounds / Q000032:analysis; D013439:Sulfhydryl Reagents
chemical_list: D001426:Bacterial Proteins; D004220:Disulfides; D046911:Macromolecular Substances; D013438:Sulfhydryl Compounds; D013439:Sulfhydryl Reagents; D004228:Dithionitrobenzoic Acid; D003545:Cysteine; D004229:Dithiothreitol