N-ethylmaleimide modification of the SH1 and SH2 groups appears to be
a frequently used method to convert the myosin S1 subunit into a
strong-binding but inactive (ATPase-wise) form of the S1. This seems
to have been a useful tool to investigate the regulatory properties of
the muscle thin filament activation and cooperativity.
Can anyone comment on the modification process? Is the actin/NEM-S1
binding constant well characterized? Is it always the same? Does NEM-
S1 precipitate out of solution over time?