19F nuclear magnetic resonance studies of selectively fluorinated derivatives of G- and F-actin.
G-Actin is a globular protein (Mr 42 300) known to have three cysteine residues that are at least partially exposed and chemically reactive (Cys-10, -284, and -374). When G-actin was reacted with 3-bromo-1,1,1-trifluoropropanone, three resolvable 19F resonances were observed in the 19F NMR spectrum. This fluorinated G-actin derivative remained fully polymerizable, and its 31P NMR spectrum was not significantly different from that of unmodified G-actin, indicating that the chemical modification did not denature the actin and the modified residues do not interfere with the extent of polymerization or the binding of adenosine 5'-triphosphate. One of the three 19F resonances was assigned to fluorinated Cys-374 on the basis of its selective reaction with N-ethylmaleimide. This resonance was dramatically broadened after polymerization of fluorinated G-actin, while the other two resonances were not markedly broadened or shifted. Thus, Cys-10 and -284 are not involved in or appreciably affected by the polymerization of G-actin, while the mobility of the 19F label at Cys-374 is markedly reduced.
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D000096:Acetone / Q000031:analogs & derivatives; D000199:Actins; D005033:Ethylmaleimide; D005461:Fluorine; D007202:Indicators and Reagents; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D011485:Protein Binding; D013329:Structure-Activity Relationship
D000199:Actins; D007202:Indicators and Reagents; D000096:Acetone; D005461:Fluorine; C004269:bromotrifluoroacetone; D005033:Ethylmaleimide