AMP-deaminase from human preterm placenta--kinetic regulatory properties of enzyme

Abstract

During pregnancy the isoform composition of human placental AMP-deaminase changes. This may reflect the adaptation of enzyme to changing metabolic requirements of the growing fetus. In this paper kinetic and regulatory properties of AMP-deaminase purified from human preterm (∼ 25 week of gestation) placenta were described and compared with these of the enzyme purified from term placenta. AMP-deaminase from preterm placenta was less sensitive to pH changes and in contrast to the enzyme from the term organ, at low range of substrate concentrations was not inhibited but activated by physiological concentrations of orthophosphate. This may significantly improve the catalytic efficiency of enzyme at early phase of the pregnancy.