Activation of an alkaline proteinase from fish skeletal muscle by fatty acids and sodium dodecyl sulphate.

1. Fish skeletal muscle contains an alkaline thiol proteinase with a temperature optimum of 60 degrees C and undetectable activity below 50 degrees C. 2. The present study shows that fatty acids and sodium dodecyl sulphate (SDS) shifted the temperature-activity curve of the enzyme toward the lower temperature side. 3. All unsaturated fatty acids tested strongly stimulated proteolytic activity at 37 degrees C, whereas myristic acid was the only saturated fatty acid that produced an important degree of activation. 4. These effects could be observed at millimolar concentrations of the reagents.