The active site of human paraoxonase (PON1).

D. Josse, Oksana Lockridge, W. Xie, C. F. Bartels, Lawrence M Schopfer, P. Masson

Research output: Contribution to journalArticle

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Abstract

Ideally we would like to treat people exposed to nerve agents with an enzyme that rapidly destroys nerve agents. The enzymes considered for such a role include human butyrylcholinesterase (BChE), acetylcholinesterase (AChE), carboxylesterase and paraoxonase (PON1). Success has been achieved in endowing BChE with the ability to hydrolyze organophosphates. The G117H mutant of BCHE hydrolyzes sarin and VX, whereas the double mutant G117H/E197Q hydrolyzes soman (Millard et al. Biochemistry 1995; 34: 15925-15933; 1998; 37: 237-247). However, the rates of organophosphate hydrolysis are slow and a faster organophosphate hydrolase is being sought. Native PON1 hydrolyzes paraoxon with a catalytic efficiency, of 2.4 x 10(6) M(-1) x min(-1), and our goal is to improve the organophosphate hydrolase activity of PON1. To achieve this we need to identify the amino acids in the active site of PON1. Using site-directed mutagenesis and expression in human 293T cells, we have identified the following eight amino acids as being essential to PON1 activity: W280, H114, H133, H154, H242, H284, E52 and D53. Fluorescence of PON1 complexed to terbium ion shows that at least one tryptophan is close to the calcium binding site.

Original languageEnglish (US)
JournalJournal of applied toxicology : JAT
Volume21 Suppl 1
StatePublished - Jan 1 2001

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Butyrylcholinesterase
Aryldialkylphosphatase
Organophosphates
Catalytic Domain
Terbium
Sarin
Soman
Paraoxon
Amino Acids
Carboxylesterase
Mutagenesis
Biochemistry
HEK293 Cells
Enzymes
Acetylcholinesterase
Site-Directed Mutagenesis
Tryptophan
Hydrolysis
Fluorescence
Binding Sites

ASJC Scopus subject areas

  • Toxicology

Cite this

The active site of human paraoxonase (PON1). / Josse, D.; Lockridge, Oksana; Xie, W.; Bartels, C. F.; Schopfer, Lawrence M; Masson, P.

In: Journal of applied toxicology : JAT, Vol. 21 Suppl 1, 01.01.2001.

Research output: Contribution to journalArticle

Josse, D. ; Lockridge, Oksana ; Xie, W. ; Bartels, C. F. ; Schopfer, Lawrence M ; Masson, P. / The active site of human paraoxonase (PON1). In: Journal of applied toxicology : JAT. 2001 ; Vol. 21 Suppl 1.
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