tokens: For wild type MutT and its E53D and E44D mutants , plots of log ( k ( cat ) ) versus pH exhibited a limiting slope of 1 on the ascending limb and then a hump , i.e. , a sharply defined maximum near pH 8 followed by a plateau , yielding apparent pK ( a ) values of 7.6 + /- 0.3 and 8.4 + /- 0.4 for an essential base and a nonessential acid catalyst , respectively , in the active quaternary MutT-Mg ( 2+ ) - dGTP-Mg ( 2+ ) complex .
folded_tokens: for wild type mutt and its e53d and e44d mutant , plot of log ( k ( cat ) ) versus ph exhibit a limit slope of 1 on the ascend limb and then a hump , i.e. , a sharply define maximum near ph 8 follow by a plateau , yield apparent pk ( a ) value of 7.6 + /- 0.3 and 8.4 + /- 0.4 for a essential base and a nonessential acid catalyst , respectively , in the active quaternary mutt-mg ( 2+ ) - dgtp-mg ( 2+ ) complex .