SERINE-CONTAINING ACTIVE CENTER OF ALKALINE PROTEINASE OF ASPERGILLUS FLAVUS

1. 1. From the soluble portion of the tryptic digest of oxidized diisopropyl [32P]-phosphoryl-derivative of alkaline proteinase of Aspergillus flavus a radioactive fragment was isolated and its amino acid composition determined to be Asp7, Met1, Thr5, Ser8, Glu4, Pro3, Gly7, Ala9, Val6, Ile5, Leu6, Tyr2 and Phe2. 2. 2. Four radioactive peptides were isolated from a partial acid hydrolysate of the slightly soluble portion of the tryptic digest. These peptides provides evidence of the amino acid sequence Gly-Thr-Ser-Met-Ala around the reactive serine residue of alkaline proteinase. This amino acid sequence represents a part of the large tryptic fragment. 3. 3. Similarities in the amino acid sequences of serine-containing active centers of microbial proteinases are discussed. © 1969.