Naslov
Reactivation of tabun inhibited AChE investigated by two oximes and mutagenesis

Autori
Katalinić, Maja ; Kovarik , Zrinka

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Book of Abstracts of the 10th Congress of the Croatian Society of Biochemistry and Molecular Biology with the international participation "The secret life of biomolecules", HDBMB 2010 / Kovarik, Zrinka ; Varljen, Jadranka - Rijeka : Hrvatsko Društvo za Biotehnologiju, 2010

Skup
10th Congress of the Croatian society of Biochemistry and Molecular Biology with international participation "The secret life of biomolecules", HDBMB 2010

Mjesto i datum
Opatija, Hrvatska, 15.09.2010. - 18.09.2010

Vrsta sudjelovanja
Poster

Vrsta recenzije
Domaća recenzija

Ključne riječi
acetylcholinesterase; tabun; oxime; reactivation; K048; K033

Sažetak
A high toxicity of nerve agent tabun arises from the irreversible inhibition of acetylcholinesterase (AChE ; EC 3.1.1.7), important enzyme in neurotransmission. The inhibition of AChE activity results in accumulation of neurotransmitter acetylcholine at vital cholinergic sites, which in turn leads to life-threatening toxic manifestations. Currently used therapy with anticholinergics (atropine) and reactivators of tabun-inhibited AChE (oximes) still has its limitations. Employment of scavenger capable of neutralizing tabun rapidly before it reaches targeted synaptic AChE, is now being considered as an alternative approach in therapy. For these purpose, we investigated the reactivation of tabun-inhibited AChE site-directed mutants assisted by two bispyridinium oximes, K048 [1-(4-hydroxyiminomethylpyridinium)-4-(4-carbamoylpyridinium) butane dibromide] and K033 [1, 4-bis(2-hydroxyiminomethylpyridinium) butane dibromide] to see if such mutant-oxime pair could act as a pseudo catalytic scavenger of tabun and be applied in detoxification or decontamination. AChE was modified within the acyl (Phe295Leu, Phe297Ile) and choline (Tyr337Ala) binding site of the active site gorge by replacing the aromatic amino acid residues with the aliphatic ones. The active site catalytic triad (Ser-His-Glu) was intact. Results show that introduced mutations affected both the affinity of phosphorylated enzyme for oximes and the rate of nucleophilic displacement of phosphoryl moiety from the catalytic serine, all compared to the wild type AChE. However, mutations significantly lowered the overall reactivation efficacy of K048, but slightly enhanced the potency of K033 to reactivate tabun-inhibited AChE. It seems that the replacement of aromatic residues at the acyl and choline binding site greatly interfered with the stabilization of the oxime’s pyridinium ring(s) within the active site gorge needed to obtain the proper orientation of the oxime group toward the phosphorylated active site serine. Since there was no significant improvement obtained in reactivation compared to the w.t. AChE, these mutant-oxime pairs could not be considered for improvement of therapy of tabun poisoning.

Izvorni jezik
Engleski

Znanstvena područja
Kemija, Temeljne medicinske znanosti, Farmacija

POVEZANOST RADA