Difference UV-absorption spectrum of scallop adductor myosin induced by ATP

A difference UV-absorption spectrum induced by ATP was observed with scallop myosins purified from both striated and smooth adductor muscles. The difference spectra showed a positive peak at 289 nm with a shoulder around 295 nm, and two small negative troughs around 280 nm. Tryptophanyl movement similar to that in rabbit skeletal myosin is indicated. Some tyrosyl movements in scallop myosins, however, may be in the opposite direction.