title: Studies on the role of sulfhydryls in the myosin ATPase. Characterization of the site of modification by the bifunctional sulfhydryl reagent p-N,N'-phenylenedimaleimide.
abstract: Myosin has been modified with near stoichiometric amounts of the bifunctional reagent [14C]p-N,N'-phenylenedimaleimide (pPDM) in the presence of MgADP under conditions which abolish its ATPase activity. Subsequent carboxymethylation and CNBr cleavage results in the 14C label being associated with a single polypeptide of Mr approximately 10,000. Amino acid composition and partial sequence analysis of this peptide showed that it corresponded to the peptide containing -SH1 and -SH2 sequenced by Elzinga and Collins (Elzinga, M., and Collins, J.H. (1977) Proc. Natl. Acad. Sci. U.S.A. 74, 4281-4284) and to the peptide labeled at -SH1 or -SH2 by N-ethylmaleimide by Kunz et al. (Kunz, P.A., Walser, J.T., Watterson, J.G., and Schaub, M.C. (1977) FEBS Lett. 83, 137-140). These data indicating that pPDM does label the -SH1- and -SH2-containing region in myosin by covalently bridging them and shows that in the presence of MgADP these thiols can approach to within 12 to 14 A.
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D001665:Binding Sites; D003488:Cyanogen Bromide; D008297:Male; D008301:Maleimides; D009132:Muscles / Q000201:enzymology*; D009218:Myosins / Q000378:metabolism*; D010446:Peptide Fragments / Q000032:analysis; D011485:Protein Binding; D011817:Rabbits; D013438:Sulfhydryl Compounds
chemical_list: D000596:Amino Acids; D008301:Maleimides; D010446:Peptide Fragments; D013438:Sulfhydryl Compounds; C011328:N,N'-4-phenylenedimaleimide; D000251:Adenosine Triphosphatases; D009218:Myosins; D003488:Cyanogen Bromide