GRAPHICAL EVALUATION OF ALKYLATION OF MYOSINS SH1 AND SH2 - THE N-PHENYLMALEIMIDE REACTION

Previous assertions about the effect of alkylation of SH1 and SH2 on t he myosin high-salt calcium and EDTA ATPases have been summarized, and a simple procedure for obtaining the fractional labeling of SH1 and S H2 after treatment of myosin with alkylating agents has been derived. A simple graphical procedure for illustrating the degree of preference of a particular alkylating agent for SH1 over SH2 has also been devel oped. The procedures we developed were validated by applying them to t wo previously studied compounds, 4-(2-iodoacetamido)-TEMPO and 2,4-din itrofluorobenzine, and then were used to determine a procedure for max imizing the extent of labeling of SH1 alone by N-phenylmaleimide, a co mpound not previously studied in this manner. It was found that simila r to 80% of the SH1 sites could be alkylated without significant alkyl ation of SH2.