title: Mechanistic studies of phosphoenolpyruvate carboxylase from Zea mays utilizing formate as an alternate substrate for bicarbonate.
abstract: Formate is an alternate substrate for bicarbonate in the reaction with PEP catalyzed by phosphoenolpyruvate carboxylase from Zea mays, producing formyl phosphate and pyruvate. The Km for formate is 25 +/- 2 mM, and the maximum velocity is 1% of that for bicarbonate at pH 8.0. Use of [18O]formate produces inorganic phosphate containing 1 equiv of 18O, but no label is incorporated into residual phosphoenolpyruvate. PEP carboxylase catalyzes the hydrolysis of phosphoglycolate or L-phospholactate 2000 times more slowly and D-phospholactate 4000 times more slowly than the reaction between bicarbonate and PEP.
authors.affiliation: Institute for Enzyme Research, University of Wisconsin, Madison 53705.
authors.forename: J W
authors.initials: JW
authors.lastname: Janc
authors.forename: W W
authors.initials: WW
authors.lastname: Cleland
authors.forename: M H
authors.initials: MH
authors.lastname: O'Leary
mesh_terms: D001639:Bicarbonates / Q000378:metabolism*; D005561:Formates / Q000378:metabolism*; D006016:Glycolates / Q000378:metabolism; D006358:Hot Temperature; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D010103:Oxygen Isotopes; D010730:Phosphoenolpyruvate Carboxylase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism; D011773:Pyruvates / Q000378:metabolism; D013379:Substrate Specificity; D003313:Zea mays / Q000201:enzymology*
chemical_list: D001639:Bicarbonates; D005561:Formates; D006016:Glycolates; D010103:Oxygen Isotopes; D011773:Pyruvates; C017092:bromopyruvate; D010744:Phosphoric Monoester Hydrolases; D010730:Phosphoenolpyruvate Carboxylase; C013193:phosphoglycolate