The ATP-induced myosin subfragment-1 fluorescence intensity increase is due to one tryptophan.
The irradiation of skeletal muscle myosin subfragment 1 (S1) in the presence of 2,2,2-trichloroethanol (TCE) reduces S1 fluorescence intensity in two phases. In the first phase, there is an increase in MgATPase activity, and no significant change in the fluorescence intensity increase upon ATP binding. In the second phase, the activity remains elevated, but there is a complete loss of the ATP-induced intensity increase. Measurements on denatured S1 indicate that fluorescence intensity reductions of one fifth of the total occur during each of the two phases, consistent with the fluorescence intensity increase upon forming S1.MgADP.P(i) being due to one of the five heavy-chain tryptophans.
Department of Biochemistry, University of the Pacific School of Dentistry, San Francisco, CA 94115.
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Highsmith
D000255:Adenosine Triphosphate / Q000737:chemistry*; D000818:Animals; D017301:Ca(2+) Mg(2+)-ATPase; D005023:Ethylene Chlorohydrin / Q000031:analogs & derivatives; D005453:Fluorescence; D009132:Muscles / Q000737:chemistry; D015879:Myosin Subfragments / Q000737:chemistry*; D009218:Myosins; D014364:Tryptophan / Q000737:chemistry*
D015879:Myosin Subfragments; D005023:Ethylene Chlorohydrin; D014364:Tryptophan; D000255:Adenosine Triphosphate; C005849:2,2,2-trichloroethanol; D017301:Ca(2+) Mg(2+)-ATPase; D009218:Myosins