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Chemical and conformational events in regions of the myosin

1975; Wiley; Volume: 3; Issue: 4 Linguagem: Inglês

10.1002/jss.400030406

1547-9366

Andrew G. Szent‐Györgyi,

Ion channel regulation and function

Abstract Structural changes in myosin may take place within the heavy chains, or may represent rearrangement of subunits. Changes induced by ATP and possibly restricted to the heavy chains are indicated by several different optical studies, including changes in absorbence of aromatic residues (1), changes in the fluorescene of dyes coupled to myosin (2), changes in electron spin resonance spectrum (3), and changes in the intrinsic fluorescence of tryptophan residues (4, 5). A calcium dependent subunit rearrangement in scallop myosin is indicated by fluorescene depolarization studies (Cheung and Szent‐Györgyi, unpublished observations). In scallop muscles, calcium regulates contraction by directly reacting with myosin (6), and the changes in the quaternary structure of myosin are likely to be related in the way calcium control works. At first I will disucss the changes of fluorenscene that Drs. Weber, Fasman, and I have described several years ago (4). Then I will speculate on the implications of a subunit rearrangement on the mechanism of regulatory light chain funciton.