Open AccessPurification and Characterization of the Isopenicillin N Synthase of Streptomyces lactamdurans
Author(s) -
José María Albertos Castro,
Paloma Liras,
Leonila Laíz,
Jesús M. Cortés,
Juan F. Martı́n
Publication year - 1988
Publication title -
microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.019
H-Index - 179
eISSN - 1465-2080
pISSN - 1350-0872
DOI - 10.1099/00221287-134-1-133
Subject(s) - streptomyces , atp synthase , chemistry , biochemistry , streptomycetaceae , enzyme , actinomycetales , stereochemistry , bacteria , biology , genetics
The isopenicillin N synthase (cyclase) of Streptomyces lactamdurans (syn. Nocardia lactamdurans) has been purified to near homogeneity as judged by SDS-PAGE and isoelectric focusing. This enzyme catalyses the oxidative cyclization of the tripeptide delta-(L-alpha-aminoadipyl)-L-cysteinyl-D-valine to isopenicillin N. The enzyme required DTT, Fe2+ and oxygen and it was greatly stimulated by ascorbic acid. It was strongly inhibited by Co2+, Zn2+ and Mn2+. Optimal pH and temperature were 7.0 and 25 degrees C (with the assay conditions used), respectively. The apparent Km of isopenicillin N synthase for delta-(L-alpha-aminoadipyl)-L-cysteinyl-D-valine was 0.18 mM. The enzyme is a monomer with an Mr of 26,500 +/- 1000 and a pI of 6.55.