Catalytic efficiencies of directly evolved phosphotriesterase variants with structurally different organophosphorus compounds in vitro.
Arch Toxicol
; 90(11): 2711-2724, 2016 Nov.
Article
em En
| MEDLINE
| ID: mdl-26612364
ABSTRACT
The nearly 200,000 fatalities following exposure to organophosphorus (OP) pesticides each year and the omnipresent danger of a terroristic attack with OP nerve agents emphasize the demand for the development of effective OP antidotes. Standard treatments for intoxicated patients with a combination of atropine and an oxime are limited in their efficacy. Thus, research focuses on developing catalytic bioscavengers as an alternative approach using OP-hydrolyzing enzymes such as Brevundimonas diminuta phosphotriesterase (PTE). Recently, a PTE mutant dubbed C23 was engineered, exhibiting reversed stereoselectivity and high catalytic efficiency (k cat/K M) for the hydrolysis of the toxic enantiomers of VX, CVX, and VR. Additionally, C23's ability to prevent systemic toxicity of VX using a low protein dose has been shown in vivo. In this study, the catalytic efficiencies of V-agent hydrolysis by two newly selected PTE variants were determined. Moreover, in order to establish trends in sequence-activity relationships along the pathway of PTE's laboratory evolution, we examined k cat/K M values of several variants with a number of V-type and G-type nerve agents as well as with different OP pesticides. Although none of the new PTE variants exhibited k cat/K M values >107 M-1 min-1 with V-type nerve agents, which is required for effective prophylaxis, they were improved with VR relative to previously evolved variants. The new variants detoxify a broad spectrum of OPs and provide insight into OP hydrolysis and sequence-activity relationships.
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MEDLINE
Assunto principal:
Compostos Organofosforados
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Praguicidas
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Pseudomonas
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Proteínas de Bactérias
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Hidrolases de Triester Fosfórico
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Agentes Neurotóxicos
Idioma:
En
Ano de publicação:
2016
Tipo de documento:
Article