Imikhiqizo

Ukulimala kwe-oxidative ezisekelweni ze-DNA kuvame ukuphumela ekwakhekeni kwama-purines ane-oxidized, ikakhulukazi i-7,8-dihydro-8-oxoguanine (8-oxoG) kanye ne-7,8-dihydro-8-oxoadenine (8-oxoA), eyake yaba umthombo wokuphila. i-mutagenic lesion eyaziwayo.Njengoba i-8-oxoG ingaphansi kwe-oxidation eyengeziwe ngokuqhathaniswa nezisekelo ezijwayelekile, ukufakwa kwesisekelo ngesikhathi sokuhlanganiswa kwe-DNA okuphambene nefomu le-oxidized ye-8-oxoG kwaphenywa ku-vitro.Isifanekiso sokwenziwa esiqukethe isilonda esisodwa se-8-oxoG saqale selashwa ngama-oxidant e-electron eyodwa noma ngaphansi kwezimo zomoya-mpilo we-singlett futhi sabe sesingaphansi kokunwetshwa kwe-primer okucushwe i-Klenow fragment exo- (Kf exo-), ithole le-thymus DNA polymerase alpha (pol alpha ) noma i-DNA polymerase beta yomuntu (pol beta).Ngokuvumelana nemibiko yangaphambilini, i-dAMP ne-dCMP zifakwa ngokukhetha ngokuphambene ne-8-oxoG nawo womathathu ama-polymerase e-DNA.Kuyathakazelisa ukuthi i-oxidation ye-8-oxoG itholakale yenza i-dAMP ne-dGMP ifakwe ngokuphambene nesilonda nge-Kf exo- ngokuvinjelwa kwesikhashana kwesandiso sokuqala o okwenzeka endaweni yesisekelo esilungisiwe.Ngaphezu kwalokho, isilonda sakha ibhulokhi ngesikhathi sokuhlanganiswa kwe-DNA nge-pol alpha ne-pol beta.Ukuhlolwa ngesifanekiso se-oligonucleotide esishintshiwe esingu-8-oxoA kubonisa ukuthi kokubili i-8-oxoA kanye nefomu elenziwe oxidized lika-8-oxoA lokufakwa ngokuqondile kwe-dTMP nge-Kf exo-.Ukuhlaziywa kwe-spectrometric enkulu yama-oligonucleotide aqukethe i-8-oxoG ngaphambi nangemuva kokufakwa kwe-oxidation nge-IrCl62-kuyahambisana ne-oxidation ngokuyinhloko yesayithi ye-8-oxoG, okuholela ekwakhekeni kwe-guanidinohydantoin moiety njengomkhiqizo omkhulu.Abukho ubufakazi bokwakhiwa kwezindawo ze-aasic obutholakele.Le miphumela ibonisa ukuthi uhlobo lwe-oxidized ye-8-oxoG, okungenzeka ukuthi i-guanidinohydantoin, lungaqondisa ukufundwa okungalungile kanye nokungafakwa kahle kwama-dNTP ngesikhathi sokuhlanganiswa kwe-DNA.Uma inqubo enjalo yenzeka ku-vivo, izomela iphuzu le-mugenic lesion eholela ekuguquleni kwe-G-->T kanye ne-G-->C.Kodwa-ke, ifomu elihambisanayo le-oxidized le-8-oxoA libonisa ngokuyinhloko ukufakwa okulungile kwe-T ngesikhathi sokuhlanganiswa kwe-DNA ne-Kf exo-.