title: Pulmonary phosphatidic acid phosphohydrolase. Developmental patterns in rabbit lung.
abstract: 1. The developmental patterns of the phosphatidic acid phosphohydrolase activities in developing rabbit lung were determined using both aqueously dispersed phosphatidic acid (PAaq) and membrane-bound phosphatidic acid (PAmb) as the substrates. 2. The specific activities and the total activities of the PAmb-dependent phosphohydrolase activities in the microsomes and to a lesser extent in the homogenates increased between 26 and 30 days gestation (term 31), but decreased in the adult. The PAaq-dependent activities demonstrated a smaller increase during late gestation and a decrease in the adult. 3. There was little change in either the Paaq- or the Pamb-dependent activities in the cytosol between 25 and 30 days gestation. The total activities per g lung were increased in the adult. 4. Fractionation of adult cytosol on Bio-Gel A5m revealed PAaq-dependent activities in the void volume (Vo) (50% total), a peak with an apparent molecular mass (Mr) = 150 kdaltons (25% total) and a peak with Mr = 110 kdaltons (25% total). The PAaq-dependent peak with Mr = 150 kdaltons was not detected in the fetal cytosols. 5. Gel filtration revealed PAmb-dependent activity in the Vo (15% total), a major peak with an apparent Mr = 390 kdaltons (44% total) and minor peaks with Mr = 240 kdaltons (16% total) and Mr = 110 kdaltons (24% total). Little change was observed during development. 6. Thermal denaturation studies on he PAmb-dependent activities in the cytosols produced biphasic curves with a rapidly inactivated component and a relatively heat-stable component. The thermal denaturation profiles for the PAmb-dependent activities remained relatively unaltered throughout fetal development. The thermal denaturation profiles of the PAaq-dependent activities in the fetal cytosols were also biphasic. In contrast, the inactivation profiles of the PAaq-dependent activities in adult cytosol were monophasic.
mesh_terms: D000375:Aging; D000818:Animals; D003600:Cytosol / Q000201:enzymology; D005333:Fetus / Q000201:enzymology; D005865:Gestational Age; D007700:Kinetics; D008168:Lung / Q000201:enzymology* / Q000254:growth & development; D008970:Molecular Weight; D010711:Phosphatidate Phosphatase / Q000302:isolation & purification / Q000378:metabolism*; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism*; D011817:Rabbits
chemical_list: D010744:Phosphoric Monoester Hydrolases; D010711:Phosphatidate Phosphatase