Mechanisms for the biodehalogenation of iodocompounds.

Received May 8,1978 SUMMARY: The in vitro deiodination of I1251]-4-iodobipheny1, [1251]-4iodonitrobenzene and [1251]-4-iodoaniline was investigated. No deiodination was detected in rat thyroid homogenates. However, at least three biodeiodination mechanisms were indicated for substrates in rat liver subcellar fractions. Microsomal dehalogenation occurred to a minor extent with increased dehalogenation taking place in the cytosol fraction. The cytosol deiodination was extensive for 4-iodonitrobenzene and was mediated by glutathione. A second cytosol deiodination mechanism, not mediated by glutathione, was evident when 4-iodobiphenyl was the substrate. This soluble enzyme system could be enhanced by Arochlor 1254 or 4-iodobiphenyl pretreatment.