Open AccessCrosslinked myosin subfragment 1: a stable analogue of the subfragment-1.ATP complex.
Author(s) -
Joseph M. Chalovich,
Lois E. Greene,
Evan Eisenberg
Publication year - 1983
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.80.16.4909
Subject(s) - tropomyosin , myosin , atp hydrolysis , actin , pi , chemistry , adenosine triphosphate , adenosine diphosphate , biochemistry , crystallography , biophysics , stereochemistry , enzyme , biology , atpase , platelet aggregation , platelet , immunology
Myosin subfragment 1 (S-1) with its two reactive cysteine groups crosslinked by N,N'-p-phenylenedimaleimide (pPDM), is shown to be a stable analogue of S-1 X ATP and S-1 X ADP X Pi, the predominant complexes present during the steady-state hydrolysis of ATP by S-1. pPDM-S-1 binds to actin with about twice the affinity of S-1 X ATP or S-1 X ADP X Pi, whereas its affinity is 1/100th of that of S-1 X 5'-adenylyl imidodiphosphate and 1/1,000th of that of S-1 X ADP. pPDM-S-1 is also similar to S-1 X ATP and S-1 X ADP X Pi in that its binding to actin is not inhibited by troponin-tropomyosin. In contrast, the binding of S-1, S-1 X ADP, and S-1 X 5'-adenylyl imidodiphosphate to actin is markedly inhibited by troponin-tropomyosin in the absence of Ca2+ when actin is in large excess over S-1. This suggests that modifying S-1 with pPDM stabilizes a conformation which mimics that induced by the binding of ATP.