Katalitičke RNA - molekulski fosili RNA-svijeta

undergraduate thesis

• Title (english): Catalytic RNAs – molecular fossils of the RNA world
• Author: Natalia Mrnjavac
• Mentor: Ita Gruić-Sovulj (mentor)
• Granter: University of Zagreb; Faculty of Science; (Department of Biology); Zagreb
• Defense date and country: 2012, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Biology

Abstract

Katalitičke RNA se ubrajaju u skupinu bioloških katalizatora, u koju spadaju i mnogo rašireniji, efikasniji i mlađi proteinski enzimi. Okosnica molekule RNA je gusto negativno nabijena s vrlo fleksibilnim vezama, a funkcionalne skupine za katalizu su malobrojne i monotone. Ipak, RNA katalizira nekoliko centralnih staničnih reakcija koristeći najviše katalizu metalnim ionima i kiselinsko-baznu katalizu, ali i doprinos vezne energije, elektrostatsku katalizu, kovalentnu, te ponekad čak i organske kofaktore i sam supstrat kao pomoć u katalizi. Mali ribozimi (hammerhead, hairpin i HDV) cijepaju sami sebe koristeći kao nukleofil 2'-OH riboze na čijem se 3' kraju nalazi veza koja podliježe cijepanju. Veliki ribozimi (introni grupe I i II) koriste hidroksilnu skupinu riboze udaljenog ili vanjskog nukleotida kao nukleofil, a sudjeluju u procesu izrezivanja introna iz pre-RNA i ligaciji eksona. U stanici postoji i nekoliko ribonukleoproteinskih kompleksa gdje RNA ima katalitičku ulogu, među kojima je najbitniji ribosom. Činjenica da RNA može sadržavati genetički zapis i omogućavati njegov kontinuitet, s jedne strane, te katalizirati kemijske reakcije, s druge, ide u prilog hipotezi o RNA-svijetu prema kojoj je ova molekula, u počecima života na Zemlji, objedinila rani metabolizam i prijenos informacije.

Abstract (english)

Catalytic RNAs are biological catalysts, a group of molecules which also comprises a much bigger number of younger and more effective catalysts – the enzymes. The RNA backbone is highly negatively charged with very flexible bonds, and the functional groups are few and monotonous. However, RNA catalyzes a few biochemical reactions that are of central importance for cells, using mostly metal ion catalysis and acid-base catalysis, as well as the contribution of binding energy, electrostatic and covalent catalysis, and even sometimes using organic cofactors and the supstrate itself as a contributing factor in catalysis. Small ribozymes (the hammerhead, hairpin and HDV) are self-cleaving; they activate the 2'-OH group of the ribose adjacent to the scissile phosphate for nucleophilic attack. In large ribozymes (group I and II introns) the nucleophile is the –OH group of the ribose of a distant or even exogenous nucleotide; they catalyze intron splicing. There are also a few ribonucleoprotein complexes in the cell in which RNA is the catalytical entity. The most important is the ribosome. The fact that RNA is a molecule that can contain genetic information and allow genetic continuity, on one hand, and can catalyze chemical reactions, on the other, is supportive of the hypothesis of an RNA world in which, during the beginnings of life on Earth, RNA combined early metabolism and information transfer.

• Keywords: katalitičke RNA
• Keywords (english): catalytic RNAs
• Language: croatian
• URN:NBN: urn:nbn:hr:217:387061
• 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: 2018-04-19 10:55:10