Synthesis of 1-(1-D-car☐y-2-methylpropyl)3-L-(5-L-aminoadipamido)-4-L-mercaptoazetidin-2-one (seco-isopenicillin N), a potential intermediate in penicillin biosynthesis

A pure enzyme catalyzing penicillin biosynthesis

Isopenicillin N synthetase (cyclase) has been purified to homogeneity from Cephalosporium acremonium strain C-10. The enzyme has a molecular weight of 40,000 to 42,000 and yields a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The enzyme was purified in 10 percent yield by a combination of protamine sulfate and ammonium sulfate precipitations, gel filtration, and ion-exchange high-performance liquid chromatography. The purified enzyme can be stabilized with sucrose and stored at -20 degrees C for several weeks without any loss in activity.