PHOSPHOENOLPYRUVATE CARBOXYLASE FROM SOYBEAN NODULE CYTOSOL - EVIDENCE FOR ISOENZYMES AND KINETICS OF THE MOST ACTIVE COMPONENT

被引:51
作者
PETERSON, JB [1 ]
EVANS, HJ [1 ]
机构
[1] OREGON STATE UNIV,NITROGEN FIXAT RES LAB,CORVALLIS,OR 97331
基金
美国国家科学基金会;
关键词
(Soybean nodule; Kinetics); Isoenzyme assay; Phosphoenolpyruvate carboxylase;
D O I
10.1016/0005-2744(79)90130-X
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
Phosphoenolpyruvate carboxylase (orthophosphate:oxaloacetate carboxylase (phosphorylating), EC 4.1.1.31) from plant cells of soybean nodules was studied to assess its role in providing carbon skeletons for aspartate and asparagine synthesis. The enzyme was purified 119-fold by (NH4)2SO4 fractionation and DEAE-cellulose, BioGel A-1.5m, and hydroxyapatite chromatography. Five activity bands were resolved with discontinuous polyacrylamide gel electrophoresis. A small quantity of enzyme from the most active band was separated from the others by preparative electrophoresis. The apparent Michaelis constants of this enzyme for phosphoenolpyruvate and HCO3- were 9.4 · 102 and 4.1 · 10-1 mM, respectively. A series of metabolites tested at 1 mM had no significant effect on enzyme activity. These experiments indicate that the major factors directly controlling phosphoenolpyruvate carboxylase activity in vivo are phosphoenolpyruvate and HCO3- concentrations. © 1979.
引用
收藏
页码:445 / 452
页数:8
相关论文
共 21 条