Activity under a gradient of increasingly oxidizing conditions to promote disulfide formation. Non-reducing SDS–PAGE reveals the relative abundance of disulfides (single measurement). Below each gel lane we show the HPLC traces indicating the corresponding activity of 50 M mini-cAMPase incubated with 200 M Mn 2+ and 250 M cAMP. The HPLC traces monitor the appearance of AMP (assayed by RP-HPLC) measured every 2 h for 24 h. The mutant C57A is included for comparison.
