Kolinesteraze i oksimi kao pseudokatalitička čistila živčanih bojnih otrova

doctoral thesis

• Title (english): Cholinesterases and oximes as pseudo-catalytic bioscavengers of nerve warfare agents
• Author: Nikolina Maček Hrvat; MBZ: 00455629430
• Mentor: Zrinka Kovarik (mentor)
• Committee member: Ines Primožič (predsjednik povjerenstva)
• Committee member: Zrinka Kovarik (član povjerenstva)
• Committee member: Jasna Vorkapić-Furač (član povjerenstva); MBZ: 53001
• Granter: University of Zagreb; Faculty of Science; (Department of Chemistry); Zagreb
• Defense date and country: 2015-04-15, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Chemistry
• Universal decimal classification (UDC): 54 - Chemistry. Crystallography. Mineralogy

Abstract

Sažetak Organofosforni spojevi (OP), kao što su živčani bojni otrovi (tabun, soman, VX),ireverzibilno inhibiraju acetilkolinesterazu (AChE) i butirilkolinesterazu (BChE). Terapija u slučaju izloženosti OP spoju je nužna i uključuje primjenu antikolinergika atropina i oksima, reaktivatora AChE. Ta terapija je nedostatna pa se danas, između ostalog, istražujupseudokatalitička čistila enzimi dizajnirani s ciljem da se njihovom cikličkom inhibicijom i reaktivacijom razgradi OP spoj prije nego što on inhibira esencijalnu sinaptičku AChE. Ispitana je učinkovitost 17 oksima u reaktivaciji ljudske AChE, BChE, Y337A i Y337A/F338A inačica AChE, inhibiranih tabunom, VX-om i somanom. Prema određenimkinetičkim parametrima izdvojeni su najučinkovitiji oksim-enzim parovi za razgradnju spomenutih OP spojeva u ex vivo uvjetima. Pokazano je da neki od ispitanih oksimima u kombinaciji s navedenim enzimima čine učinkovit sustav pseudokatalitičkog čistila za razgradnju tabuna (1-heksil-2-(hidroksiiminometil)piridinijev klorid (JAR288C) i Y337A), VX-a (HI-6 i Y337A/F338A) te somana (HI-6 i Y337A/F338A). Značajne odlike ovih parova oksima i inačica AChE su maksimalna konstanta brzine reaktivacije viša od 0,2 min-1, disocijacijska konstanta oksim-enzim kompleksa oko 0,1 mmol dm-3, visoki postotak reaktivacije te konstanta brzine inhibicije barem reda veličine one za nativnu AChE. Ovi kinetički parametri predstavljaju nužne kriterije za razgradnju OP spojeva potpomognutu oksimom i enzimom, odnosno za učinkovita pseudokatalitička čistila živčanih bojnih otrova.

Abstract (english)

Organophosphates (OP) such as nerve agents (tabun, soman, VX) irreversibly inhibit acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). The treatment in case of exposure to OP compounds includes the administration of the anticholinergic drug atropine and an oxime reactivator. Since this therapy has proven insufficient, today, among other solutions, pseudo-catalytic bioscavengers, enzymes designed with the aim to degrade OPs with turnover before it interacts with synaptic AChE, are investigated as prophylactics. We tested 17 oximes as reactivators of human AChE, BChE, Y337A and the Y337A/F338A mutant of AChE inhibited by tabun, VX and soman. The most effective oxime-enzyme couples identified were further tested ex vivo for degradation of tabun, VX or soman by oxime-enzyme assisted hydrolysis. It was shown that among the studied oximes there were those that in combination with the investigated enzymes could serve as pseudo-catalytic bioscavengers of tabun (oxime 1-hexyl-2-(hydroxyimino)methylpyridinium chloride (JAR288C) and Y337A mutant), VX (oxime HI-6 and Y337A/F338A mutant) and soman(oxime HI-6 and Y337A/F338A mutant). The tested oximes and AChE mutant pairs reactivated a high percentage of enzyme activity, achieving reactivation rate constants above0.2 min-1, oxime-mutant dissociation constants about 0.1 mol min-1 dm-3 and a rate of enzyme inhibition within the range of native AChE inhibition. These catalytic parameters represent the necessary criteria for oxime-enzyme induced OP degradation, i.e. for effective nerve agent pseudo-catalytic bioscavengers.

• Keywords: acetilkolinesteraza; butirilkolinesteraza; inačice acetilkolinesteraze; organofosforni spojevi; reaktivatori
• Keywords (english): acetylcholinesterase; acetylcholinesterase mutants; butyrylcholinesterase; organophosphates; reactivators
• Language: croatian
• URN:NBN: urn:nbn:hr:217:354902
• Study programme: Title: Doctoral study in chemistry; Study programme type: university; Study level: postgraduate; Academic / professional title: doktor/doktorica znanosti, područje prirodnih znanosti, polje kemija (doktor/doktorica znanosti, područje prirodnih znanosti, polje kemija)
• Type of resource: Text
• Extent: 111 str. ; 30 cm
• File origin: Born digital
• Access conditions: Open access
• Created on: 2017-02-09 15:13:14