PHOSPHOPYRIDINE NUCLEOTIDE LINKED DEHYDROGENASES, ALDOLASE AND FUMARASE IN MOUSE BREAST

Abstract

Methods are presented for measuring five enzymes in 1 to 5 gamma frozen-dried samples of mouse mammary duct, fat or connective tissue. Effects of incubation temperature, pH, and substrate and pyridine nucleotide concentrations on activity of the five mammary enzymes are reported. Lactic, malic and isocitric dehydrogenases are stable for at least 49 days in mouse mammary gland when stored frozen and dried at -20[degree]C. Aldolase and fumarase activities decline after 21 days. Activities of these five enzymes and of glucose-6-phosphate dehydrogenase do not significantly change from estrus to diestrus in mouse mammary duct. Levels of lactic, malic and glucose-6-phosphate dehydrogenases and aldolase and fumarase are greatly increased in duct of lactating mammary gland as compared to that from pregnant breast. Isocitric dehydrogenase does not significantly increase during lactation. This paper presents validation of methods which are useful for the study of five enzymes of breast. The glucose-6-phosphate dehydrogenase method is presented in a companion paper. The activities of these enzymes and of glucose-6-phosphate dehydrogenase are measured in mammary duct of mice in four hormonal states estrus, diestrus, pregnancy and lactation. These methods and observations may provide the basis for study of enzymes during carcinogenesis, hormonal alterations, and other physiological and pathological processes in breast.