Glucose-sensitive adenylate cyclase in toluene-treated cells of Escherichia coli B.

Toluene treatment of Escherichia coli B makes it possible to measure adenylate cyclase activity directly using [alpha-32-P]-ATP as substrate. In contrast to French press extracts, the activity of adenylate cyclase in toluene-treated cells shows many of the characteristics of the enzyme seen in the intact cell. In both toluene-treated and intact cells the activity of adenylate cyclase is inhibited at least 85% by glucose, while in French press extracts the enzyme activity is much lower and is not sensitive to inhibition by glucose. In toluene-treated cells, glucose inhibits at 10 muM, and the effect is rapid in onset and readily reversible. The activity is not inhibited by glucose 6-phosphate suggesting that glucose is responsible for the inhibition. The measurement of the activity and sensitivity to glucose of adenylate cyclase in toluene-treated cells requires the presence of potassium phosphate in the assay medium. Since it does not increase the activity or sensitivity of the enzyme in the French press extract, it is suggested that potassium phosphate is required for the maintenance of cellular integrity necessary for the activity and sensitivity of adenylate cyclase.