A hydrophobic region on myosin light chains modulated by divalent cations.
A hydrophobic region was detected on several types of myosin light chain by enhancement of the quantum yield of 1-anilino-8-naphthalenesulfonate (ANS) fluorescence. The character of this non-polar region was altered by the binding of Ca2+ or Mg2+ to the light chain, the quantum yield of the ANS being increased, and its emission maximum undergoing a blue-shift. These changes enabled the binding of divalent cations to the myosin light chains to be monitored. When Ca2+ was bound to gizzard regulatory light chain, a biphasic enhancement of light-chain-bound ANS fluorescence occurred, the first phase taking place in the micromolar range and the second in the millimolar range of free Ca2+ concentration. Enhancement of protein-bound ANS fluorescence as divalent cations were bound was also observed with other types of myosin light chain.
Hardwicke
P M
PM
Department of Medical Biochemistry, Southern Illinois University, Carbondale 62901.
Huvos
P
P
D000817:Anilino Naphthalenesulfonates / Q000378:metabolism; D000818:Animals; D001665:Binding Sites; D002118:Calcium / Q000378:metabolism / Q000494:pharmacology*; D002645:Chickens; D005456:Fluorescent Dyes; D005895:Gizzard, Avian / Q000032:analysis; D008274:Magnesium / Q000378:metabolism / Q000494:pharmacology*; D008974:Mollusca; D009218:Myosins / Q000378:metabolism*; D013050:Spectrometry, Fluorescence
D000817:Anilino Naphthalenesulfonates; D005456:Fluorescent Dyes; C027132:1-anilino-8-naphthalenesulfonate; D009218:Myosins; D008274:Magnesium; D002118:Calcium