Comparative Kinetic Stabilities of Staphylococcal Enterotoxin Types A, B, and C1.

摘要

Staphylococcal enterotoxin types A and C1 were observed by viscometry and near-ultraviolet difference spectroscopy to unfold at concentrations of aqueous guanidine hydrochloride greater than 1M. Apparent rate constants of unfolding calculated from spectral curves differed markedly for the two enterotoxins. Rate constants for the unfolding of enterotoxin A in 2 or 3 M guanidine hydrochloride solution were 30- to 40-fold larger in value than those observed for enterotoxin C1. In contrast, rate constants for the unfolding of enterotoxin C1 in 4 or 5 M guanidine hydrochloride solution were only 4- to 5-fold larger than those previously reported for enterotoxin type B. In addition, the types B and C1 enterotoxins unfolded at nearly identical rates in 6 M guanidine hydrochloride and 8 M urea solution.