Azocar O, Muñoz E. Molecular organization in bacterial cell membranes. Sulfhydryl groups and disulfide bridges in Streptomyces albus and Escherichia coli K 12 cytoplasmic membranes.
EUROPEAN JOURNAL OF BIOCHEMISTRY 1976;
68:245-54. [PMID:
786637 DOI:
10.1111/j.1432-1033.1976.tb10784.x]
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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.
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