SERUM LEVELS AND BIOCHEMICAL CHARACTERIZATION OF OESTRADIOL-17β DEHYDROGENASE IN UMBILICAL CORD BLOOD

: The properties of the enzyme oestradiol-17 beta dehydrogenase from human umbilical cord serum have beem compared with those of oestradiol-17 beta dehydrogenase present in the maternal peripheral blood. On the basis of studies on stability, specificity, optimum pH, rate of enzymic reaction and Km determinations it can be concluded that oestradiol-17 beta dehydrogenase in the umbilical cord arteries has an activity between 5 and 15 times higher than in the umbilical cord vein and about 65% of the activity of the enzyme present in the maternal peripheral blood. The present results strongly suggest that in pregnancy the enzyme oestradiol-17 beta dehydrogenase is elaborated not only by the placenta but also by the foetus.