A fluorescence quenching study of tryptophanyl residues of (Ca2+ + Mg2+)-ATPase from sarcoplasmic reticulum.
The tryptophan intrinsic fluorescence of the (Ca2+ + Mg2+)-ATPase from sarcoplasmic reticulum was quenched by acrylamide at different temperatures. Sharp increases in the quenching constants were found in samples of ATPase reconstituted with dimyristoyl-phosphatidylcholine and dipalmitoylphosphatidylcholine at temperatures slightly below the Tc transition temperature of the pure phospholipid. It is suggested that acrylamide may diffuse more easily through proteins surrounded by a fluid phospholipid matrix than if they are in a rigid matrix, due to different states of protein fluidity.
Gómez-Fernández
J C
JC
Baena
M D
MD
Teruel
J A
JA
Villalaín
J
J
Vidal
C J
CJ
D000818:Animals; D017301:Ca(2+) Mg(2+)-ATPase; D000252:Calcium-Transporting ATPases / Q000378:metabolism*; D004134:Dimyristoylphosphatidylcholine / Q000494:pharmacology; D007700:Kinetics; D009132:Muscles / Q000201:enzymology; D011663:Pulmonary Surfactants / Q000494:pharmacology; D011817:Rabbits; D012519:Sarcoplasmic Reticulum / Q000201:enzymology*; D013050:Spectrometry, Fluorescence / Q000379:methods; D013816:Thermodynamics; D014364:Tryptophan / Q000032:analysis*
D011663:Pulmonary Surfactants; D014364:Tryptophan; D017301:Ca(2+) Mg(2+)-ATPase; D000252:Calcium-Transporting ATPases; D004134:Dimyristoylphosphatidylcholine