Table 1.

The enzymatic activity of Cys to Ser mutants of bovine MsrA

Cysteines replaced	Activity, %
	DTT	Thioredoxin
None (WT)	100	100
72	0	0
107	114	96
218	35	22
227	89	19
72, 218	0.7	0
107, 218	22	6
107, 227	96	14
218, 227	42	4
72, 107, 227	0	0
107, 218, 227	39	8

Activity of 100% represents 580 and 1,250 pmol of N-Ac-l-[³H]Met produced in the DTT and thioredoxin assays, respectively. Each value represents the average of three independent measurements at two enzyme concentrations (SD range 5–10%).