Effect of N-[N-(L-trans-3-carboxyoxirane-2-carbonyl)- L-leucyl]-3-methyl-butylamine (E64C), a Thiol- Protease Inhibitor, on Tyrosine Release from Skeletal Muscle Cells

Abstract

Low concentrations (μg/ml level) of N-[N-(L-trans-3-carboxyoxirane- 2-carbonyl)-L-leucyl]-3-methyl-butylamine (E64C), a thiol-protease inhibitor, inhibited tyrosine release from skeletal muscle cells in which tyrosine release had been enhanced. Increase in cytoplasmic Ca²⁺ concentration seemed to be one of the factors that promoted the tyrosine release. These findings were discussed in relation to the mode of the protein degradation in the cells by thiolproteases including calcium-activated neutral protease.