349609-57-0Relevant academic research and scientific papers
Substrate Analogues for the Enzyme-Catalyzed Detoxification of the Organophosphate Nerve Agents—Sarin, Soman, and Cyclosarin
Bigley, Andrew N.,Harvey, Steven P.,Narindoshvili, Tamari,Raushel, Frank M.
, p. 2875 - 2887 (2021/10/01)
The G-type nerve agents, sarin (GB), soman (GD), and cyclosarin (GF), are among the most toxic compounds known. Much progress has been made in evolving the enzyme phosphotriesterase (PTE) fromPseudomonas diminutafor the decontamination of the G-agents; however, the extreme toxicity of the G-agents makes the use of substrate analogues necessary. Typical analogues utilize a chromogenic leaving group to facilitate high-throughput screening, and substitution of anO-methyl for theP-methyl group found in the G-agents, in an effort to reduce toxicity. Till date, there has been no systematic evaluation of the effects of these substitutions on catalytic activity, and the presumed reduction in toxicity has not been tested. A series of 21 G-agent analogues, including all combinations ofO-methyl,p-nitrophenyl, and thiophosphate substitutions, have been synthesized and evaluated for their ability to unveil the stereoselectivity and catalytic activity of PTE variants against the authentic G-type nerve agents. The potential toxicity of these analogues was evaluated by measuring the rate of inactivation of acetylcholinesterase (AChE). All of the substitutions reduced inactivation of AChE by more than 100-fold, with the most effective being the thiophosphate analogues, which reduced the rate of inactivation by about 4-5 orders of magnitude. The analogues were found to reliably predict changes in catalytic activity and stereoselectivity of the PTE variants and led to the identification of the BHR-30 variant, which has no apparent stereoselectivity against GD and akcat/Kmof 1.4 × 106, making it the most efficient enzyme for GD decontamination reported till date.
Stereoselective detoxification of chiral sarin and soman analogues by phosphotriesterase
Li, Wen-Shan,Lum, Karin T.,Chen-Goodspeed, Misty,Sogorb, Miguel A.,Raushel, Frank M.
, p. 2083 - 2091 (2007/10/03)
The catalytic activity of the bacterial phosphotriesterase (PTE) toward a series of chiral analogues of the chemical warfare agents sarin and soman was measured. Chemical procedures were developed for the chiral syntheses of the SP- and RP-enantiomers of O-isopropyl p-nitrophenyl methylphosphonate (sarin analogue) in high enantiomeric excess. The RP-enantiomer of the sarin analogue (kcat = 2600 s-1) was the preferred substrate for the wild-type PTE relative to the corresponding SP-enantiomer (kcat = 290 s-1). The observed stereoselectivity was reversed using the PTE mutant, I106A/F132A/H254Y where the kcat values for the RP- and SP-enantiomers were 410 and 4200 s-1, respectively. A chemo-enzymatic procedure was developed for the chiral synthesis of the four stereoisomers of O-pinacolyl p-nitrophenyl methylphosphonate (soman analogue) with high diastereomeric excess. The RPRC-stereoisomer of the soman analogue was the preferred substrate for PTE. The kcat values for the soman analogues were measured as follows: RPRC, 48 s-1; RPSC, 4.8 s-1; SPRC, 0.3 s-1, and SPSC, 0.04 s-1. With the I106A/F132A/H254Y mutant of PTE the stereoselectivity toward the chiral phosphorus center was reversed. With the triple mutant the kcat values for the soman analogues were found to be as follows: RPRC, 0.3 s-1; RPSC, 0.3 s-1; SPRC, 11 s-1, and SPSC, 2.1 s-1. Prior investigations have demonstrated that the SP-enantiomers of sarin and soman are significantly more toxic than the RP-enantiomers. This investigation has demonstrated that mutants of the wild-type PTE can be readily constructed with enhanced catalytic activities toward the most toxic stereoisomers of sarin and soman.
