The sulfhydryl groups of the thiol-dependent cytolytic toxin from Bacillus alvei evidence for one essential sulfhydryl group |
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Authors: | C Geoffroy A M Gilles J E Alouf |
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Affiliation: | 2. Unité de Chimie des Protéines Institut Pasteur, 28, rue du Docteur Roux, 75724 Paris Cedex 15, France |
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Abstract: | Alveolysin, an extracellular protein toxin (Mr ? 63,000) excreted by Bacillus alvei and purified to homogeneity was shown to contain four cysteine residues. All thiol groups of the hemolytically active toxin preparation were free as found by direct titration by 5,5′-dithiobis (2-nitrobenzoic acid) and confirmed by the absence of disulfide bond. Toxin alkylation with tosyl lysine chloromethyl ketone resulted in the complete loss of hemolytic activity and the disappearance of only one thiol group with no modification of histidine residues. These results support the conclusion that one essential thiol group is implicated in the membrane-disrupting activity of alveolysin. |
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Keywords: | TLCK N-α-p-tosyl-L-lysine chloromethyl ketone DTT dithiothreitol HU hemolytic unit BAEE α-N-benzyl-L-arginine ethyl ester PBS phosphate-buffered saline DTNB 5,5′-dithiobis (2-nitrobenzoic acid) |
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