Purification and properties of the phosphotriesterase from Pseudomonas diminuta. Academic Article uri icon

abstract

  • The phosphotriesterase produced from the opd cistron of Pseudomonas diminuta was purified 1500-fold to homogeneity using a combination of gel filtration, ion exchange, hydrophobic, and dye matrix chromatographic steps. This is the first organophosphate triesterase or organophosphofluoridate hydrolyzing enzyme to be purified to homogeneity. The enzyme is a monomeric, spherical protein having a molecular weight of 39,000. A single zinc atom is bound to the enzyme and is required for catalytic activity. Incubation with metal chelating compounds, o-phenanthroline, EDTA, or 2,6-pyridine dicarboxylate inactivate the enzyme. The kinetic rate constants, kcat and kcat/Km, for the hydrolysis of paraoxon are 2100 s-1 and 4 x 10(7) M-1 s-1, respectively. The enzyme is inhibited competitively by dithiothreitol, dithioerithritol, and beta-mercaptoethanol. In addition to paraoxon the phosphotriesterase was found to hydrolyze the commonly used organophosphorus insecticides, dursban, parathion, coumaphos, diazinon, fensulfothion, methyl parathion, and cyanophos.

published proceedings

  • J Biol Chem

altmetric score

  • 7

author list (cited authors)

  • Dumas, D. P., Caldwell, S. R., Wild, J. R., & Raushel, F. M.

citation count

  • 441

complete list of authors

  • Dumas, DP||Caldwell, SR||Wild, JR||Raushel, FM

publication date

  • January 1989