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γ‐Amido‐ATP stabilizes a high‐fluorescence state of myosin subfragment 1
Author(s) -
Wray John,
Jahn Werner
Publication year - 2002
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(02)02654-6
Subject(s) - myosin , adenosine triphosphate , actin , chemistry , fluorescence , atp hydrolysis , biophysics , tryptophan , cleavage (geology) , dissociation (chemistry) , dissociation constant , stereochemistry , biochemistry , enzyme , biology , atpase , amino acid , paleontology , physics , quantum mechanics , fracture (geology) , receptor
On binding to myosin subfragment 1 (S1), the γ‐amido derivative of ATP (ATPγNH 2 ), an isomer of adenosine 5′‐[β,γ‐imido]‐triphosphate (AMPPNP), induces a larger increase in the intrinsic (tryptophan) fluorescence than is seen with ATP. A binding constant of 1.7×10 7 M −1 was measured for ATPγNH 2 , compared to 2.1–2.4×10 7 M −1 for AMPPNP. ATPγNH 2 was hydrolyzed only very slowly by S1. ATPγNH 2 appears to stabilize the ‘closed’ conformation of S1, and does so without cleavage of the β–γ phosphate bond. The dissociation of actin‐S1 by ATPγNH 2 and that of S1.ATPγNH 2 by actin are both strikingly slow.