β-Galactosidase from Termination and Deletion Mutant Strains

摘要: beta-Galactosidase fragments were isolated from strains of Escherichia coli with mutations in the lacZ gene. The polypeptide obtained a termination mutant (lacZNG125) appeared to be intact gene product, containing first half beta-galactosidase amino acid sequence. From an internal deletion strain (lacZU163), aggregate was several partially degraded polypeptides. Each these smaller than predicted genetic data for fragment. Introduction lacZU163 mutation into protein degradation-deficient (Deg(-)) resulted protection amino-terminal region protein. Some BrCN peptides U163 polypeptides separated and identified. such experiments it shown that both Deg(-) Deg(+) COOH-terminal is rapidly degraded. This indicates complete product has not been detected. use genetically defined enzyme studying structure-function relationships determination primary structure discussed.