The pesticides have facilitated the development and
also expansion of agriculture in world wide. Organophosphate belong to a class
of highly toxic neurotoxins that are commonly used as pesticides and chemical
warfare agent (Surekha Rani et al. 2008).
The continuous use of organophosphate in intensive quantity throughout the
world and their potential neurotoxicity to humans has wind to the development
of various efficient and safety scheme of bioremediation to plenty with their
wide dispersal in the ecosystem (Cho et al. 2002). Enzymatic degradation by
organophosphorus hydrolase (OPH) has received considerable attention. This
attention provides the possibility of both eco friendly and in situ
detoxification (Catherine et al. 2002). The focussing of this study is
organophosphorus hydrolase (OPH, E.C. 220.127.116.11), which catalyzes the hydrolysis
of many organophosphorus compounds and highly reduces the toxicity of organophosphate
pesticide and it can completely mineralize the organophosphate componds.
The OPH enzyme was coded by opd gene, were found
in two soil microorganisms namely Pseudomonas diminuta MG and Flavobacterium
sp. (Sethunathan et al. 1998). Although
OPH hydrolyzes a wide range of organophosphate componds, the effectiveness of
hydrolysis varies dramatically for differnt componds. Widely used
organophosphorus insecticides like methyl parathion, chlorpyrifos, and diazinon
are hydrolyzed slowly than 30 to 1,000 times is the preferred substrate,
paraoxon (Cho et al. 2002). This reduction in catalytic rate is due to the
unfavorable interaction of these substrates with the active sites involved in
catalysis and/or structural functions (Zheng
et al. 2013).
A number of enzymes are capable of hydrolysing a
number of organophosphate triesters into less or non-toxic compounds. These
enzymes are possible bioremediators because of their ability to decontaminate
OP-containing waters and soils (Zheng et al. 2013). The most thoroughly
characterized phosphotriesterases have been isolated from Flavobacterium sp.
ATCC 27551, Pseudomonas diminuta (OPH) and Agrobacterium radiobacter (OpdA)
(Fernanda et al. 2010). These enzymes belong
to the binuclear metallohydrolase family and share high sequence and
structural homology. Phosphotriesterases are highly promiscuous enzymes,
hydrolysing a large range of substrates. The phosphotriester hydrolysis by OPH
has been studied extensively (Castro et al. 2016).
In a proposed reaction scheme, based on largely crystal structures with bound
inhibitors, the phosphoryl oxygen of the substrate binds to the ?-metal
ion (Janet et al.2005; Laothanachareo et al. 2008).
In the present research focuses on the
interaction and degradation of chlorpyrifos by OPH enzyme, as this is
responsible for detoxification. The molecular docking study was conducted under
FlexX docking software package.