ISOLATION AND STRUCTURE ELUCIDATION OF 2 NEW CALPAIN INHIBITORS FROM STREPTOMYCES-GRISEUS

Two new peptides, a diketopiperazine of N-methyltyrosine (1) and a tet rapeptide containing N-methyltyrosine (2), were isolated from an actin omycete strain Streptomyces griseus. These compounds inhibit the enzym e calpain in the micromolar range and were characterized on the basis of spectroscopic analysis, amino acid analysis and sequencing. The str ucture of the tetrapeptide N-methyltyrosyl-N-methyltyrosyl-leucyl-alan ine (2), was also confirmed by total synthesis.