Sodium dodecyl sulfate-induced conformational and enzymatic changes of multicatalytic proteinase.

Chymotrypsin-like activity of the multicatalytic proteinase (MCP) purified from eggs of the ascidian Halocynthia roretzi was activated by the addition of SDS. Complete activation was achieved simultaneously at the time of SDS addition, and this activity decreased as a function of time. Autonomous fluorescence of MCP also increased rapidly at the time of SDS addition and then decreased at a rate that depended on the SDS concentration. The decrease of autonomous fluorescence induced by SDS preceded that of the activity. These results suggest that a rapid conformational change of MCP induced by SDS results in the enhancement of chymotrypsin-like activity, followed by the decrease of this activity because of the lability of the activated conformation.