Sawada Y, Hunt N A, Demain A L
J Antibiot (Tokyo). 1979 Dec;32(12):1303-10. doi: 10.7164/antibiotics.32.1303.
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.
利用抗生素阴性突变体顶头孢霉M-0198的原生质体裂解物将青霉素N微生物环扩展为去乙酰氧头孢菌素C的速率比我们早期的体系提高了约70倍。我们证实了Hook等人（《生物化学与生物物理学研究通讯》87: 258, 1979）所述硫酸亚铁和抗坏血酸盐的刺激作用；发现的最佳浓度分别为0.04 mM硫酸亚铁和0.67 mM抗坏血酸盐。三磷酸腺苷浓度降至0.83 mM；磷酸烯醇丙酮酸和丙酮酸激酶被去除。该反应的最佳pH值和温度分别为7.2和25℃。α-酮戊二酸和氯化锰对反应无明显影响，硫酸镁和氯化钾有轻微刺激作用，硫酸铜和硫酸锌有很强的抑制作用。青霉素N的最佳浓度为0.07 mM。比环扩展活性在生长停止后13小时达到峰值，然后迅速消失。
