title: Further studies on microbiological ring-expansion of penicillin N.
abstract: The rate of microbiological ring-expansion of penicillin N to deacetoxycephalosporin C using protoplast lysates of the antibiotic-negative mutant Cephalosporium acremonium M-0198 has been increased some 70-fold over that of our earlier system. We confirmed the stimulatory effects of FeSO4 and ascorbate described by Hook et al. (Biochem. Biophys. Res. Commun. 87: 258, 1979); the optimum concentrations found were 0.04 mM FeSO4 and 0.67 mM ascorbate. Adenosine triphosphate concentration was lowered to 0.83 mM; phosphoenolpyruvate and pyruvate kinase were eliminated. The optimum pH and temperature for the reaction were 7.2 and 25 degrees C, respectively. Alpha-ketoglutarate and MnCl2 showed no marked effect on the reactions, MgSO4 and KCl were mildly stimulatory, and CuSO4 and ZnSO4 were very inhibitory. Penicillin N was optimal at a concentration of 0.07 mM. Specific ring-expansion activity reached its peak 13 hours after growth ceased and then disappeared rapidly.
mesh_terms: D000164:Acremonium / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000494:pharmacology; D001711:Biotransformation; D006863:Hydrogen-Ion Concentration; D010406:Penicillins / Q000378:metabolism*; D010728:Phosphoenolpyruvate / Q000494:pharmacology; D011506:Proteins / Q000378:metabolism; D011550:Pseudomonas aeruginosa / Q000378:metabolism; D011770:Pyruvate Kinase / Q000494:pharmacology; D013696:Temperature; D013997:Time Factors
chemical_list: D010406:Penicillins; D011506:Proteins; D010728:Phosphoenolpyruvate; D000255:Adenosine Triphosphate; D011770:Pyruvate Kinase