title: Kinetic challenges facing oxalate, malonate, acetoacetate, and oxaloacetate decarboxylases.
abstract: To compare the powers of the corresponding enzymes as catalysts, the rates of uncatalyzed decarboxylation of several aliphatic acids (oxalate, malonate, acetoacetate, and oxaloacetate) were determined at elevated temperatures and extrapolated to 25 °C. In the extreme case of oxalate, the rate of the uncatalyzed reaction at pH 4.2 was 1.1 × 10(-12) s(-1), implying a 2.5 × 10(13)-fold rate enhancement by oxalate decarboxylase. Whereas the enzymatic decarboxylation of oxalate requires O(2) and Mn(II), the uncatalyzed reaction is unaffected by the presence of these cofactors and appears to proceed by heterolytic elimination of CO(2).
authors: Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, North Carolina 27599-7260, United States. water@med.unc.edu
authors: Richard
authors: R
authors: Wolfenden
authors: Charles A
authors: CA
authors: Lewis
authors: Yang
authors: Y
authors: Yuan
mesh_terms: D001412:Bacillus subtilis / Q000201:enzymology; D002262:Carboxy-Lyases / Q000378:metabolism*; D007700:Kinetics; D008314:Malonates / Q000378:metabolism; D010070:Oxalates / Q000378:metabolism
chemical_list: D008314:Malonates; D010070:Oxalates; C030290:malonic acid; D002262:Carboxy-Lyases; C071852:malonate decarboxylase; C021916:oxaloacetate decarboxylase; C021915:oxalate decarboxylase; C023743:acetoacetate decarboxylase