Segmental motion and rotational diffusion of the Ca2+-translocating adenosine triphosphatase of sarcoplasmic reticulum, measured by time-resolved phosphorescence depolarization.
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ABSTRACT: 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.
SUBMITTER: Speirs A
PROVIDER: S-EPMC1152091 | biostudies-other | 1983 Jul
REPOSITORIES: biostudies-other
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