小鼠乳腺癌胆色素原酶和羟甲基胆色素原合成酶。

Mouse mammary carcinoma porphobilinogenase and hydroxymethylbilane synthetase.

Navone N M, Polo C F, Frisardi A L, Batlle A M

Centro de Investigaciones sobre Porfirinas y Porfirias (CIPYP), CONICET-FCEN, UBA, Ciudad Universitaria, Buenos Aires, Argentina.

Comp Biochem Physiol B. 1991;98(1):67-71. doi: 10.1016/0305-0491(91)90309-2.

Abstract

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.

摘要

对来自小鼠乳腺癌、正常小鼠肝脏和荷瘤小鼠肝脏的粗提物中的胆色素原酶（PBGase）和羟甲基胆色烷合成酶（HMB-S）进行了研究。2. 在任一来源中均观察到这两种酶的米氏动力学。PBGase的Km值为87至108微摩尔，Vmax为1.57 - 1.83纳摩尔卟啉/2小时，希尔系数n = 1；HMB-S的Km值为13至19微摩尔，Vmax为2.6 - 4.8。3. 在所有情况下，PBGase和HMB-S孵育长达180分钟时卟啉合成呈线性，且随着孵育温度升高而大幅增加，在60℃时达到最大值，70℃时为零，任一来源中任一种酶的最适温度均为37℃。4. 尿卟啉原III合成酶受热失活，而HMB-S是一种热稳定酶。任一组织中PBGase和HMB-S的最适pH均为8.2。