Aspects on diamine oxidase activity and its determination

Abstract
Homogenate of guinea pig liver and human placenta, tissues known to be rich in diamine oxidase [EC 1.4.3.6], were incubated with 14C-putrescine and the metabolites formed were determined. In the incubate of guinea pig liver, the major metabolites were GABA and some unidentified compound(s); .DELTA.1-pyrroline and 14CO2 were also obtained. In both the maternal and fetal parts of human placenta, radioactive GABA and the unidentified compound(s) as well as .DELTA.1-pyrroline were found. GABA is an important intermediate in putrescine metabolism. Determination of the amount of .DELTA.1-pyrroline is thus not well suited as a measure of the diamine oxidase activity in tissues.