Studies on synthesis of alpha-tyrosinase in E. intermedia were conducted in continuous culture with glucose as a carbon source and tyrosine as an inducer. Dynamic responses in the specific activity of the alpha-tyrosinase, RNA content in cells, cell and glucose concentrations were monitored. The specific synthesis rate of alpha-tyrosinase and its corresponding ribosomal efficiency, defined as the enzyme synthesis rate per unit weight of RNA, were estimated to study the kinetics and regulation of the enzyme synthesis in steady-state culture. Sustained oscillation in alpha-tyrosinase activity was observed for continuous culture at low dilution rates. This might be due to the interacting effect of the induction by tyrosine and of the repression by phenol formed endogenously from tyrosine assimilation on alpha-tyrosinase protein synthesis. The specific rate of the enzyme synthesis was found to be proportional to the specific growth rate of the cell. The ribosomal efficiency for enzyme synthesis increased linearly with the specific growth rate. Much more glucose metabolism might be required to achieve a high rate and efficient protein synthesis for extremely fast growing cells and, thus, resulted in a lower cellular yield. Synthesis of alpha-tyrosinase was repressed by glucose metabolism. Increasing the feeding glucose concentration led to a lowering in ribosomal efficiency and slight increase in RNA content in cells. The glucose effect on ribosomal efficiency was further elucidated by adding stimulator or inhibitor to regulate gene transcription.
