Kinetic interactions of a neuropathy potentiator (phenylmethylsulfonyl fluoride) with the neuropathy target esterase and other membrane bound esterases
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- 作者：Iris Mangas (1)
Eugenio Vilanova (1)
Jorge Estévez (1) - 关键词：Phenylmethylsulfonyl fluoride (PMSF) ; Promotion of OPIDN ; Potentiation of OPIDN ; Organophosphate ; induced delayed neuropathy (OPIDN) ; Organophosphate ; induced delayed polyneuropathy (OPIDP) ; Serine esterases ; Brain ; Neuropathy target esterase (NTE) ; Organophosphorus compounds
- 刊名：Archives of Toxicology
- 出版年：2014
- 出版时间：February 2014
- 年：2014
- 卷：88
- 期：2
- 页码：355-366
- 全文大小：740 KB
- 作者单位：Iris Mangas (1)
Eugenio Vilanova (1)
Jorge Estévez (1)
1. Unit of Toxicology and Chemical Safety, Institute of Bioengineering, University “Miguel Hernández- Elche, Alicante, Spain - ISSN：1432-0738
文摘
Phenylmethylsulfonyl fluoride (PMSF) is a protease and esterase inhibitor that causes protection, or potentiation/“promotion,-of organophosphorus delayed neuropathy (OPIDN), depending on whether it is dosed before or after an inducer of delayed neuropathy, such as mipafox. The molecular target of the potentiation/promotion of OPIDN has not yet been identified. The kinetic data of phenyl valerate esterase inhibition by PMSF were obtained with membrane chicken brain fractions, the animal model and tissue in which neuropathy target esterase (NTE) was first described. Data were analyzed using a kinetic model with a multienzymatic system in which inhibition, simultaneous chemical hydrolysis of the inhibitor and “ongoing inhibition-(inhibition during the substrate reaction) were considered. Three main esterase components were discriminated: two sensitive enzymatic entities representing 44 and 41?%, with I 50 (20?min) of 35 and 198?μM at 37?°C, respectively, and a resistant fraction of 15?% of activity. The estimated constant of the chemical hydrolysis of PMSF was also calculated (kh?=?0.28?min?). Four esterase components were globally identified considering also previously data with paraoxon and mipafox: EPα (4-?%), highly sensitive to paraoxon and mipafox, spontaneously reactivates after inhibition with paraoxon, and resistant to PMSF; EPβ (38-1?%), sensitive to paraoxon and PMSF, but practically resistant to mipafox, this esterase component has the kinetic characteristics expected for the PMSF potentiator target, even though paraoxon cannot be a potentiator in vivo due to high AChE inhibition; EPγ (NTE) (39-8?%), paraoxon-resistant and sensitive to the micromolar concentration of mipafox and PMSF; and EPδ (10?%), resistant to all the inhibitors assayed. This kinetic characterization study is needed for further isolation and molecular characterization studies, and these PMSF phenyl valerate esterase components will have to be considered in further studies of OPIDN promotion. A simple test for monitoring the four esterase components is proposed.