Activity patterns of several enzymes of liver, adipose tissue, and mammary gland of virgin, pregnant, and lactating mice.

Abstract

SummaryGlucose-ATP phosphotransferases (glucokinase and hexokinase), glucose-6-PO4 dehydrogenase, malic enzyme, and citrate-cleavage enzyme were assayed in the 100,000 × g supernatant fraction (Fraction III) of liver, inguinal fat pads cleared of mammary gland tissue, abdominal adipose tissue, and mammary gland excised from virgin, pregnant, and lactating mice of the C3H strain. In addition, the activity of glucose-ATP phosphotransferases in the 350 × g supernatant fraction (Fraction I) and that associated with mitochondria of these same tissues was measured. Mitochondria isolated from adipose tissue contained only a small quantity of glucose-ATP phosphotransferase activity. No evidence for such activity was detected in mitochondria isolated from livers of lactating mice. Mitochondria from the mammary glands of lactating mice contributed more than 60% of the total glucose-ATP phosphotransferase activity of the cell, whereas those from virgin and pregnant mice contributed less than 17%.The specific activit...