TABLE 3.

Purification of halomethane:bisulfide/halide ion methyltransferase from cell extracts of the methylotroph strain CC495

Stage of purification	Vol (ml)	Total enzyme activity (U)a	Yield (%)	Protein (mg/ml)	Sp act (U/mg of protein)
Cell extract	2	267b	100	46.3	2.88b
Anion-exchange chromatography and dialysis	2	209	78.3	4.4	23.7
Gel filtration on Superose 12	5	124	46.4	0.42	58.9

^aOne unit of enzyme activity is defined as the amount of fully activated enzyme required to catalyze the formation of 1 nmol of CH₃I min⁻¹ at 25°C in 50 mM phosphate buffer (pH 7.0) with 3 mM KI, 0.5 mM DTT, and 0.5 mM CH₃Cl. 

^bEnzyme activity measured after dialysis against 50 mM phosphate buffer (pH 7.0) containing 0.5 mM DTT.