Abstract
The pregnancy-induced activity of diamine oxidase (DAOpr) disappears from blood plasma after parturition with a ‘half-life’ (T1/2) of 30 hours, whereas transfused DApr is eliminated with T1/2 about 20 hours. In contrast, the in creased plasma activity of DAO in heparinized subjects (DAOhep) has a T1/2 of about 1 hour in the eliminatory phase, and, when transfused, DAOhep is with drawn from circulation with a T1/2 of about 3 min. In vitro studies of DAOpr and DAOhep have shown very similar enzyme characteristics of DAOpr and DAOhep, whereas they differed in electrophoretic mobility. DAOhep and DAOpr may thus be regarded as diamine oxidase isoenzymes.