Regulation of thymidine metabolism in Escherichia coli K-12: optimal conditions for the assay of 1,5-phosphodeoxyribomutase in ultrasonic extracts.

Assay conditions have been established which allow maximum expression of phosphodeoxyribomutase activity in ultrasonic extracts of Escherichia coli K-12. The enzyme requires 2-mercaptoethanol, manganous ions, and glucose 1,6-diphosphate for optimal activity. When cells are grown in minimal medium with glycerol as the carbon source and supplemented with 10(-3)m thymidine, phosphodeoxyribomutase is induced three- to four-fold. Cell pellets may be frozen for 24 hr before sonic disruption without loss of enzyme activity. The assay is highly reproducible.