Isopenicillin N synthetase of Penicillium chrysogenum, an enzyme that converts delta-(L-alpha-aminoadipyl)-L-cysteinyl-D-valine to isopenicillin N.
AUTOR(ES)
Ramos, F R
RESUMO
The tripeptide delta-(L-alpha-aminoadipyl)-L-cysteinyl-D-valine, an intermediate in the penicillin biosynthetic pathway, is converted to isopenicillin N by isopenicillin N synthetase (cyclase) of Penicillium chrysogenum. The cyclization required dithiothreitol and was stimulated by ferrous ions and ascorbate. Co2+ and Mn2+ completely inhibited enzyme activity. Optimal temperature and pH were 25 degrees C and 7.8, respectively. The reaction required O2 and was stimulated by increasing the dissolved oxygen concentration of the reaction mixture. Purification of the enzyme to a single major band in polyacrylamide gel electrophoresis was achieved by protamine sulfate precipitation, ammonium sulfate fractionation (50 to 80% of saturation), DEAE-Sephacel chromatography, and gel filtration on Sephacryl S-200. The estimated molecular weight was 39,000 +/- 1,000. The apparent Km of isopenicillin N synthetase for delta-(L-alpha-aminoadipyl)-L-cysteinyl-D-valine was 0.13 mM. The enzyme activity was strongly inhibited by glutathione, which acts as a competitive inhibitor. A good correlation was observed between the isopenicillin N synthetase activity in extracts of four different strains of P. chrysogenum (with widely different penicillin-producing capability) and the amount of penicillin production by these strains.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=176281Documentos Relacionados
- Isopenicillin N Synthetase of Penicillium chrysogenum, an Enzyme That Converts δ-(l-α-Aminoadipyl)-l-Cysteinyl-d-Valine to Isopenicillin N
- Cell-free cyclization of delta-(L-alpha-aminoadipyl)-L-cysteinyl-D-valine to isopenicillin N.
- Glucose represses formation of delta-(L-alpha-aminoadipyl)-L-cysteinyl-D-valine and isopenicillin N synthase but not penicillin acyltransferase in Penicillium chrysogenum.
- Purification and partial characterization of delta-(L-alpha-aminoadipyl)-L-cysteinyl-D-valine synthetase from Streptomyces clavuligerus.
- Presence of δ-(l-α-Aminoadipyl)-l-Cysteinyl-d-Valine in Fermentations of Penicillium chrysogenum