Rat placentae gamma-glutamyltransferase activity changes during pregnancy.

gamma-Glutamyltransferase (D-gamma-glutamyl transpeptidase, EC 2.3.2.2) activity in rat placentae changes during gestation. The enzyme activity reaches a peak during the second trimester on a per gram of tissue basis and coincides with the greatest placental growth (hyperplasia) period. However, the enzyme activity on a per placenta basis shows two peak activity periods. One coincides with the peak of activity determined on a per gram basis. The second peak occurs in the third trimester and appears to coincide with the period of greatest fetal growth. The occurrence of these enzyme changes supports the concept of a developmental role for gamma-glutamyltransferase in providing amino acids from glutathione to the placenta and fetus.