The application of pesticides has facilitated thedevelopment and expansion of agriculture globally. Organophosphates belong to aclass of highly toxic neurotoxins that are commonly used as insecticides andchemical warfare agents (Surekha Rani et al. 2008).The continuous use of organophosphates in intensive quantities throughout theworld and their potential neurotoxicity to humans has led to the development ofvarious efficient and safe bioremediation strategies to deal with their widedispersal in the ecosystem. Enzymatic degradation by organophosphorus hydrolase(OPH) has received considerable attention since it provides the possibility ofboth eco friendly and in situ detoxification (Catherine et al. 2002). Thefocus of this work is organophosphorus hydrolase (OPH, E.
C. 220.127.116.11), whichcatalyzes the hydrolysis of many organophosphorus compounds and greatly reducesthe toxicity and even can completely mineralize them.
Identical opd genes coding for OPH were foundin two soil microorganisms, Pseudomonas diminuta MG and Flavobacteriumsp. (Sethunathan et al. 1998). AlthoughOPH hydrolyzes a wide range of organophosphates, the effectiveness ofhydrolysis varies dramatically.
Widely used organophosphorus insecticides likemethyl parathion, chlorpyrifos, and diazinon are hydrolyzed 30 to 1,000 timesslower than is the preferred substrate, paraoxon. This reduction in catalyticrate is due to the unfavorable interaction of these substrates with the activesites involved in catalysis and/or structural functions (Zheng et al. 2013).A number of enzymes are capable of hydrolysing abroad range of OP triesters into less or non-toxic compounds. These enzymes arepossible bioremediators because of their ability to decontaminate OP-containingwaters and soils. The most thoroughly characterized phosphotriesterases havebeen isolated from Flavobacterium sp.
ATCC 27551, Pseudomonasdiminuta (OPH) and Agrobacterium radiobacter (OpdA) (Fernanda et al.2010). These enzymes belong to the binuclearmetallohydrolase family and share high sequence and structural homology.Phosphotriesterases are highly promiscuous enzymes, hydrolysing a large rangeof substrates. The mechanism of phosphotriester hydrolysis by OPH has beenstudied extensively (Castro et al. 2016).
Ina proposed reaction scheme based largely on crystal structures with boundinhibitors, the phosphoryl oxygen of the substrate binds to the ?-metalion (Janet et al.2005).In the present research focuses on theinteraction and degradation of chlorpyrifos by OPH enzyme, as this isresponsible for detoxification. The molecular docking study was conducted underFlexX docking software package.