x. 105. and. the. desired. temperature. 37 C. Normal leukocytes showed a fairly constant behavior with respect to total ... Enzyme activity, assayed by the method of Chiu and Sung, began to ina crease sfter 18 days on 3a#39;aMDAB and ... template speca ificity, Mg2+ requirements, and responses to monovala ent ion concentrations. ... The former enzyme had maximum activity in 10 mM MgClz compared with the 15-25 mM MgCL2 required for the maximum activity of the 3- AS enzyme.