Sod-Moriah G

References (6)

Title : The role of AChE active site gorge in determining stereoselectivity of charged and noncharged VX enantiomers - Ordentlich_2005_Chem.Biol.Interact_157-158_191
Author(s) : Ordentlich A , Barak D , Sod-Moriah G , Kaplan D , Mizrahi D , Segall Y , Kronman C , Karton Y , Lazar A , Marcus D , Velan B , Shafferman A
Ref : Chemico-Biological Interactions , 157-158 :191 , 2005
Abstract : The reactivity of human acetylcholinesterase (HuAChE) toward the chemical warfare agent VX [O-ethyl S-[2-(diisopropylamino)ethyl] methyl-phosphonothioate] and its stereoselectivity toward the P(S)-enantiomer were investigated by examining the reactivity of HuAChE and its mutant derivatives toward purified enantiomers of VX and its noncharged isostere nc-VX [O-ethyl S-(3-isopropyl-4-methyl-pentyl) methylphosphonothioate]. Stereoselectivity of the wild-type HuAChE toward VX(S) is manifested by a 115-fold higher bimolecular rate constant (1.4 x 10(8) min(-1) M(-1)) as compared to that of VX(R). HuAChE was also 12,500-fold more reactive toward VX(S) than toward nc-VX(S), demonstrating the significance of the polar interactions of the ammonium substituent to their overall affinity toward VX. Indeed, substitution of the cation-binding subsite residue Trp86 by alanine resulted in a decrease of three orders of magnitude in HuAChE reactivity toward both VX enantiomers, with only a marginal effect on the reactivity toward the enantiomers of nc-VX. These results demonstrate that accommodation of the charged moieties of both VX enantiomers depends predominantly on interactions with the aromatic moiety of Trp86. Yet, these interactions seem to limit the stereoselectivity toward the P(S)-enantiomer, which for charged methylphosphonates is much lower than for the noncharged analogs, like sarin or soman. Marked decrease in stereoselectivity toward VX(S) was observed following replacements of Phe295 at the acyl pocket (F295A and F295A/F297A). Replacement of the peripheral anionic site (PAS) residue Asp74 by asparagine (D74N) practically abolished stereoselectivity toward VX(S) (a 130-fold decrease), while substitution which retained the negative charge at position 74 (D74E) had no effect. The results from kinetic studies and molecular simulations suggest that the differential reactivity toward the VX enantiomers originates predominantly from a different orientation of the charged leaving group with respect to residue Asp74. Such different orientations of the charged leaving group in the HuAChE adducts of the VX enantiomers seem to be a consequence of intramolecular interactions with the bulky phosphorus alkoxy group.
ESTHER : Ordentlich_2005_Chem.Biol.Interact_157-158_191
PubMedSearch : Ordentlich_2005_Chem.Biol.Interact_157-158_191
PubMedID: 16289014

Title : Bifunctional compounds eliciting both anti-inflammatory and cholinergic activity as potential drugs for CNS disorders. -
Author(s) : Amitai G , Adani R , Rabinovitz I , Beit-Yanai E , Shohami E , Sod-Moriah G , Meshulam H
Ref : Cholinergic Mechanisms, CRC Press :277 , 2004
PubMedID:

Title : Poster (56) The bifunctional compound IBU-PO elicits prolonged anti-inflammatory and cholinesterase inhibition in vivo -
Author(s) : Amitai G , Adani R , Rabinovitz I , Shohami E , Sod-Moriah G , Meshulam H
Ref : In: Cholinesterases in the Second Millennium: Biomolecular and Pathological Aspects , (Inestrosa NC, Campos EO) P. Universidad Catolica de Chile-FONDAP Biomedicina :350 , 2004
PubMedID:

Title : Stereoselectivity toward VX is determined by interactions with residues of the acyl pocket as well as of the peripheral anionic site of AChE - Ordentlich_2004_Biochemistry_43_11255
Author(s) : Ordentlich A , Barak D , Sod-Moriah G , Kaplan D , Mizrahi D , Segall Y , Kronman C , Karton Y , Lazar A , Marcus D , Velan B , Shafferman A
Ref : Biochemistry , 43 :11255 , 2004
Abstract : The origins of human acetylcholinesterase (HuAChE) reactivity toward the lethal chemical warfare agent O-ethyl S-[2-(diisopropylamino)ethyl] methylphosphonothioate (VX) and its stereoselectivity toward the P(S)-VX enantiomer (VX(S)) were investigated by examining the reactivity of HuAChE and its mutant derivatives toward purified enantiomers of VX and its noncharged isostere O-ethyl S-(3-isopropyl-4-methylpentyl) methylphosphonothioate (nc-VX) as well as echothiophate and its noncharged analogue. Reactivity of wild-type HuAChE toward VX(S) was 115-fold higher than that toward VX(R), with bimolecular rate constants of 1.4 x 10(8) and 1.2 x 10(6) min(-1) M(-1). HuAChE was also 12500-fold more reactive toward VX(S) than toward nc-VX(S). Substitution of the cation binding subsite residue Trp86 with alanine resulted in a 3 order of magnitude decrease in HuAChE reactivity toward both VX enantiomers, while this replacement had an only marginal effect on the reactivity toward the enantiomers of nc-VX and the noncharged echothiophate. These results attest to the critical role played by Trp86 in accommodating the charged moieties of both VX enantiomers. A marked decrease in stereoselectivity toward VX(S) was observed following replacements of Phe295 at the acyl pocket (F295A and F295A/F297A). Replacement of the peripheral anionic site (PAS) residue Asp74 with asparagine (D74N) practically abolished stereoselectivity toward VX(S) (130-fold decrease), while a substitution which retains the negative charge at position 74 (D74E) had no effect. The results from kinetic studies and molecular simulations suggest that the differential reactivity toward the VX enantiomers is mainly a result of a different interaction of the charged leaving group with Asp74.
ESTHER : Ordentlich_2004_Biochemistry_43_11255
PubMedSearch : Ordentlich_2004_Biochemistry_43_11255
PubMedID: 15366935

Title : Oxidative biodegradation of phosphorothiolates by fungal laccase - Amitai_1998_FEBS.Lett_438_195
Author(s) : Amitai G , Adani R , Sod-Moriah G , Rabinovitz I , Vincze A , Leader H , Chefetz B , Leibovitz-Persky L , Friesem D , Hadar Y
Ref : FEBS Letters , 438 :195 , 1998
Abstract : Organophosphorus (OP) insecticides and nerve agents that contain P-S bond are relatively more resistant to enzymatic hydrolysis. Purified phenol oxidase (laccase) from the white rot fungus Pleurotus ostreatus (Po) together with the mediator 2,2'-azinobis(3-ethylbenzthiazoline-6-sulfonate) (ABTS) displayed complete and rapid oxidative degradation of the nerve agents VX and Russian VX (RVX) and the insecticide analog diisopropyl-Amiton with specific activity: k(sp) = 2200, 667 and 1833 nmol min(-1) mg(-1), respectively (pH 7.4, 37 degrees C). A molar ratio of 1:20 for OP/ABTS and 0.05 M phosphate at pH 7.4 provided the highest degradation rate of VX and RVX. The thermostable laccase purified from the fungus Chaetomium thermophilium (Ct) in the presence of ABTS caused a 52-fold slower degradation of VX with k(sp) = 42 nmol min(-1) mg(-1). The enzymatic biodegradation products were identified by 31P-NMR and GC/MS analysis.
ESTHER : Amitai_1998_FEBS.Lett_438_195
PubMedSearch : Amitai_1998_FEBS.Lett_438_195
PubMedID: 9827544

Title : Quaternary-Lipophilic Carbamates with Blood Brain Barrier Permeability as Potential Drugs for the Treatment of Diseases Associated with Cholinergic Deficiency -
Author(s) : Amitai G , Adani R , Rabinovitz I , Sod-Moriah G , Brandeis R , Rachaman E , Heldman E
Ref : In: Structure and Function of Cholinesterases and Related Proteins - Proceedings of Sixth International Meeting on Cholinesterases , (Doctor, B.P., Taylor, P., Quinn, D.M., Rotundo, R.L., Gentry, M.K. Eds) Plenum Publishing Corp. :277 , 1998
PubMedID: