Abstract

Ca²⁺-adenosine triphosphatase (ATPase) is an intrinsic membrane enzyme of muscle microsomes. The enzymic translocation of Ca²⁺ across the sarcoplasmic reticulum membrane is mediated by the formation of a phosphoenzyme intermediate in which the substrate is ATP. This procedure is believed to be accompanied by a conformational change in the protein molecule. Coupling between enzyme phosphorylation and the conformation of the Ca²⁺- ATPase has already received indirect support from certain biochemical experiments. In this paper, we report a new direct approach to investigate this coupling by monitoring laser-induced phosphorescence anisotropy from the triplet-label eosin bound covalently to the Ca²⁺- ATPase.

© 1992 IQEC