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

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Abstract
The reconstituting effect of unsaturated fatty acids whose chain length varied between C6–C24 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 C16–C18 and whose double bonds are in the middle of the chain.