Streptomyces griseus Aminopeptidase (SGAP)

From Proteopedia

Streptomyces griseus Aminopeptidase (SGAP)

Biological function

S. griseus Aminopeptidase (SGAP; E.C. 3.4.11.-) cleaves the N-terminal amino acid from a peptide or protein, and is specific for larger hydrophobic acids, especially leucine. No cleavage occurs if the next residue is proline.

Reaction catalyzed by SGAP; scissile bond is shown in red.

Biological Context

SGAP is one of the many proteinases present in the extracellular fluid of cultures of Streptomyces griseus, and can be isolated from Pronase, the commercial preparation of the extracellular fluid from this organism. SGAP is a monomeric, 30KDa, heat stable enzyme requiring two Zn²⁺ ions for activity, and is activated by Ca²⁺.

Historical Context

The proteolytic activity contained in the extracellular fluid of cultures of Streptomyces griseus was first identified by Nomoto and Narahashi (1959a), who obtained a highly purified preparation of this activity from the K-1 strain of this bactreria. A large scale version of their procedure was used to preparre commercial quantities of this preparation (Pronase). Various physicla criteira showe dthat Pronase was homogeneous (Nomoto and Narahashi, 1959b), yet displayed both exopeptidase and endopeptidase activity, with a wide range of side chain specificities (Nomoto and Narahashi, 1959b, 1959c; Nomoto et al., 1960a, 1960b; 1960c). The