Characterization of ethoxyresorufin O-de-ethylase in grey seal Halichoerus Grypus

Abstract

1. Ethoxyresorufin O-de-ethylase (EROD), a typical mixed function oxidase enzyme, was studied in liver and kidney of adult and pup grey seals, Halichoerus grypus. 2. EROD activity was present in most liver samples but was only barely detectable in a few of the kidney samples. 3. Liver EROD activity was greatest at pH 7.5–8.0; activity increased with temperature from 20°C to a plateau starting at about 33°C and extending to 37°C, and fell off sharply above 37°C. 4. K m values ranged from 3 × 10 −7 to 3 × 10 −6M; V max ranged from 5 ×l0 −12 to 1 × 10 −10moles product formed min −1mg protein −. 5. Liver EROD activity was not detectable in pups < 1 day old, and activity increased with age in pups up to 5–12 days old. Adults had greater EROD activity than did pups.