Variation of scallop sarcoplasmic reticulum Ca super(2+)-ATPase activity with temperature

Methods for preparing native scallop, Placopecten magellanicus , sarcoplasmic reticulum vesicles, largely purified membranous scallop sarcoplasmic reticulum Ca super(2+)-ATPase, and nonionic detergent-solubilized sarcoplasmic reticulum Ca super(2+)-ATPase are described. The effect of a range of polyoxyethylene-based detergents on the solubilized Ca super(2+)-ATPase was tested. Arrhenius plots of Ca super(2+)-ATPase activity, where the assays were carried out with the same pH at all temperatures (7.4), showed a region of nonlinearity at 10 degree C. The break in the Arrhenius plot and the activation energies for the scallop sarcoplasmic reticulum were very similar to those found for lobster sarcoplasmic reticulum.