Ribozimi

undergraduate thesis

• Title (english): Ribozymes
• Author: Nikolina Zoko
• Mentor: Mirjana Kalafatić (mentor)
• Granter: University of Zagreb; Faculty of Science; (Department of Biology); Zagreb
• Defense date and country: 2009, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Biology

Abstract

Ribozimi su katalitičke molekule koje moraju biti savijene u visoko uređene tercijarne strukture, kao što to proteini rade da bi obavljali svoje funkcije. Glavni cilj je dovesti nukleofil i izrezujući fosfat u blizinu i aktivirati ih. Nukleolitički ribozimi imaju nukleofil i izrezujući fosfat unutar nukleotida, i imaju relativno jednostavne strukture, zbog čega su aktivne strukture brže formirane. Nukleofil i izrezujući fosfat velikih ribozima su ili razdvojeni većom udaljenošću ili se nalaze u različitim molekulama, stoga je njima složenije prepoznati izrezujuće mjesto i dovesti supstrat u aktivno mjesto. Metalni ioni i proteinski faktori su obično uključeni u savijanje velikih ribozima. Npr., Mg2+ je nužan za vezanje supstrata i rješavanje visoko nabijenog aktivnog mjesta RNaze P. Većina introna grupe II treba proteinske faktore da im pomognu u savijanju. Veliki ribozimi, kao što su RNaza P, ribozimi grupe I i grupe II, su metaloenzimi u kojima metalni ioni direktno sudjeluju u katalizi. Na temelju osnovne reakcije koju većina ribozima provodi, koja katalizira mjesno specifično cijepanje ili ligaciju ciljne RNA, i na temelju činjenice da veliki broj ribozima djeluje in trans, ribozimi se koriste u genskoj terapiji, uništavajući mRNA ciljnih gena ili spašavanjem defektnih gena. Postoji hipoteza o postojanju RNA svijeta na Zemlji koji je prethodio DNA i proteinskom svijetu. Obavljena su brojna istraživanja u posljednje vrijeme koja daju moguće dokaze za takvu hipotezu. Najvjerojatnije je nekakav replikaza ribozim predstavljao takav RNA svijet jer je imao mogućnost autoreplikacije i katalize. Unatoč tim istraživanjima još ne postoje sigurni dokazi koji bi potvrdili hipotezu o postojanju RNA svijeta.

Abstract (english)

Ribozymes are catalytic molecules, which must be folded into highly ordered tertiary folds, as the protein enzymes did to carry out their function. The ultimate objective is to bring the nucleophile and the scissile phosphate together and activate them. The nucleolytic ribozymes have inner-nucleotide nucleophile and scissile phosphate, and have relatively simple structures, thus the active structure is more readily formed. The nucleophile and scissile phosphate of large ribozymes are either remotely separated or in different molecules, thus it’s more complicated for them to recognize the splicing site and bring the substrate to the active site. Metal ions and protein factors are usually involved in the folding of the large ribozymes. For instance, Mg2+ is required in the substrate binding and the resolution of the highly charged active site of RNase P. The major-ity of group II introns need protein factors to assist their folding. More importantly, large ribozymes like RNase P, group I and group II ribozymes are metalloenzymes, in which metal ions directly participate in ca-talysis. Based on the fundamental reaction the majority of the ribozymes carry out, which catalyze site-specific cleavage or ligation of target RNA, and on the fact that many ribozymes function in trans, ribozymes are applied in gene therapy, by digesting the mRNA of target genes or by rescuing defective genes. There is a hypothesis about existance of a RNA world on Earth, which preceded DNA and protein world. Many experiments were made recently that give possible evidences for such hypothesis. Most likely there was some kind of a replicase ribozyme which represented that RNA world because it had features of autoreplication and catalysis. In spite of these experiments, there are no certain evidences which could prove this hypothesis about existance of a RNA world.

• Keywords: ribozimi
• Keywords (english): ribozymes
• Language: croatian
• URN:NBN: urn:nbn:hr:217:232588
• Study programme: Title: Molecular Biology; Study programme type: university; Study level: undergraduate; Academic / professional title: sveučilišni/a prvostupnik/prvostupnica (baccalaureus/baccalaurea) molekularne biologije (sveučilišni/a prvostupnik/prvostupnica (baccalaureus/baccalaurea) molekularne biologije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2018-03-20 13:04:03