Open AccessAlfalfa Root Nodule Carbon Dioxide Fixation
Author(s) -
Carroll P. Vance,
S. Stade
Publication year - 1984
Publication title -
plant physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.554
H-Index - 312
eISSN - 1532-2548
pISSN - 0032-0889
DOI - 10.1104/pp.75.1.261
Subject(s) - phosphoenolpyruvate carboxylase , polyacrylamide gel electrophoresis , biochemistry , pyruvate carboxylase , gel electrophoresis , phosphoenolpyruvate carboxykinase , root nodule , chromatography , chemistry , isozyme , sodium dodecyl sulfate , size exclusion chromatography , enzyme , carbon fixation , agarose , photosynthesis , nitrogen fixation , organic chemistry , nitrogen
A nonphotosynthetic phosphoenolpyruvate carboxylase (EC 4.1.1.31) was partially purified from the cytosol of root nodules of alfalfa. The enzyme was purified 86-fold by ammonium sulfate fractionation, DEAE-cellulose, hydroxylapatite chromatography, and reactive agarose with a final yield of 32%. The enzyme exhibited a pH optimum of 7.5 with apparent K(m) values for phosphoenolpyruvate and magnesium of 210 and 100 micromolar, respectively. Two isozymes were resolved by nondenaturing polyacrylamide disc gel electrophoresis. Subsequent electrophoresis of these isozymes in a second dimension by sodium dodecyl sulfate slab gel electrophoresis yielded identical protein patterns for the isozymes with one major protein band at molecular weight 97,000. Malate and AMP were slightly inhibitory (about 20%) to the partially purified enzyme. Phosphoenolpyruvate carboxylase comprised approximately 1 to 2% of the total soluble protein in actively N(2)-fixing alfalfa nodules.