Marked enhancement in the reductive dehalogenation of hexachloroethane by a Thr319Ala mutation of cytochrome P450 1A2.

Mutation of the conserved Thr319 residue to Ala of cytochrome P4501A2 (CYP1A2) increased the value of Vmax 9-fold for reductive dehalogenation of hexachloroethane in the reconstituted system under anaerobic conditions. The Thr319Ala mutation also increased the elimination over substitution product ratio by 5-fold. The addition of aliphatic alcohols increased by 22-fold the activity obtained with the wild type and varied the elimination over substitution product ratio. Increasing pH increased the ratio of elimination over substitution by primarily affecting the rate of elimination.