Unsaturated Fatty Acids as Reactivators of the Calcium‐Dependent ATPase of Delipidated Sarcoplasmic Membranes

Abstract

The reconstituting effect of unsaturated fatty acids whose chain length varied between C 6 –C 24 on delipidated sarcoplasmic membranes has been analyzed. The reconstituted sarcoplasmic ATPase requires 70–106 mol fatty acid per 100000 dalton for optimal activity. Half‐maximal activity of the reconstituted sarcoplasmic ATPase is reached between 0.2 μM and 0.6 μM ionized calcium. The ATPase activities of the reconstituted vesicular preparations show an identical steep decline at pH values > 7, whereas the native preparation still exhibits a considerable activity at pH 8.0. The most effective reactivating unsaturated fatty acids are those with a chain length of C 16 –C 18 and whose double bonds are in the middle of the chain.