Purification of mouse liver cytosolic epoxide hydrolase

Cytosolic epoxide hydrolase was purified from male Swiss mouse liver cytosol by passing it sequentially through CM-cellulose, DEAE-cellulose, phenylsepharose, DEAE-cellulose, and hydroxyapatite. The overall yield was ca. 10% with a 180-fold purification, and a final specific activity of 1.5 mumol/min/mg protein as monitored with trans-stilbene oxide. The purified epoxide hydrolase was apparently homogenous as determined by SDS-PAGE and it appears to exist as a dimer in its native form as evidenced by a monomeric molecular weight of 59,000 by SDS-PAGE and a reported native molecular weight of 130,000 by gel filtration.