Temperature-induced ultraviolet absorption changes of heavy meromyosin. An application of a computerized...

The UV absorption of HMM (heavy meromyosin) was measured at various temperatures with a computerized spectrophotometer system. HMM showed temperature-induced absorption changes in the presence and absence of nucleotides. The temperature-induced absorption change at 293 nm, which is due to conformational changes around the tryptophan residues of HMM, was enhanced in the presence of nucleotides. The temperature-induced difference spectra of HMM + AMPPNP relative to HMM obtained by using a conventional spectrophotometer [(1977) J. Biochem. (Tokyo) 81, 313-320] could be reproduced by subtracting the temperature-induced spectral changes of HMM from those of HMM + AMPPNP.