title: Mouse mammary carcinoma porphobilinogenase and hydroxymethylbilane synthetase.
abstract: 1. Porphobilinogenase (PBGase) and hydroxymethylbilane synthetase (HMB-S) were investigated in crude extracts from mouse mammary carcinoma, normal mouse liver and tumor bearing mouse liver. 2. A Michaelis-Menten kinetics for both enzymes in either source was observed. Km values of 87 to 108 microM, Vmax of 1.57-1.83 nmol porphyrins/2 hr and a Hill coefficient of n = 1 were obtained for PBGase and Km values of 13 to 19 microM and Vmax of 2.6-4.8 were obtained for HMB-S. 3. Porphyrin synthesis was linear up to 180 min of incubation in all cases for PBGase and HMB-S, and greatly increased with higher incubation temperature being maximal at 60 degrees C and nil at 70 degrees C, optimal temperature was 37 degrees C for either enzyme in either source. 4. Uroporphyrinogen III synthetase was heat inactivated while HMB-S was a heat stable enzyme. Optimum pH was 8.2 for PBGase and HMB-S in either tissue.
authors.affiliation: Centro de Investigaciones sobre Porfirinas y Porfirias (CIPYP), CONICET-FCEN, UBA, Ciudad Universitaria, Buenos Aires, Argentina.
authors.forename: N M
authors.initials: NM
authors.lastname: Navone
authors.forename: C F
authors.initials: CF
authors.lastname: Polo
authors.forename: A L
authors.initials: AL
authors.lastname: Frisardi
authors.forename: A M
authors.initials: AM
authors.lastname: Batlle
mesh_terms: D000642:Ammonia-Lyases / Q000378:metabolism*; D000818:Animals; D006863:Hydrogen-Ion Concentration; D011163:Hydroxymethylbilane Synthase / Q000378:metabolism*; D007700:Kinetics; D008099:Liver / Q000201:enzymology; D008297:Male; D008325:Mammary Neoplasms, Experimental / Q000201:enzymology*; D051379:Mice; D008807:Mice, Inbred BALB C; D009368:Neoplasm Transplantation; D011166:Porphyrins / Q000096:biosynthesis; D013696:Temperature
chemical_list: D011166:Porphyrins; D011163:Hydroxymethylbilane Synthase; D000642:Ammonia-Lyases; C100132:porphobilinogenase