Segmental motion and rotational diffusion of the Ca2+-translocating adenosine triphosphatase of sarcoplasmic reticulum, measured by time-resolved phosphorescence depolarization.
We studied the rotational mobility of the Ca2+ + Mg2+-activated ATPase in skeletal-muscle sarcoplasmic-reticulum vesicles, using time-resolved measurements of the depolarization of laser-flash-excited phosphorescence of the extrinsic triplet probe erythrosin. Our results are in general agreement with those of others [Bürkli & Cherry (1981) Biochemistry 20, 138-145] obtained by linear dichroism methods. In addition, we directly observed fast depolarization in the 1-5 microseconds time range that can be attributed to limited motion of part of the protein (segmental motion). Temperature-dependent changes in phosphorescence anisotropy indicated the onset of a conformational change in structure of the Ca2+ + Mg2+-activated ATPase at 11-13 degrees C. We also describe the synthesis of 5-iodoacetamidoerythrosin.
D000251:Adenosine Triphosphatases / Q000378:metabolism; D000818:Animals; D017301:Ca(2+) Mg(2+)-ATPase; D000252:Calcium-Transporting ATPases / Q000378:metabolism*; D055598:Chemical Phenomena; D002621:Chemistry; D004923:Erythrosine / Q000031:analogs & derivatives; D066298:In Vitro Techniques; D017879:Isothiocyanates; D008163:Luminescent Measurements; D011487:Protein Conformation; D011817:Rabbits; D012519:Sarcoplasmic Reticulum / Q000201:enzymology*; D013997:Time Factors
D017879:Isothiocyanates; C022232:erythrosine isothiocyanate; C038909:iodoacetamidoerythrosin; D000251:Adenosine Triphosphatases; D017301:Ca(2+) Mg(2+)-ATPase; D000252:Calcium-Transporting ATPases; D004923:Erythrosine