Abstract
The HDV ribozyme is proposed to catalyze its self cleavage reaction by a proton transfer mechanism wherein the N3 of its C75 acts as a general acid. The C75 to U mutation, which raises the N3 pKa from about 4 to almost 10, abolishes all enzymatic activity. To test if a U analogue with a neutral pKa can restore ribozyme function we incorporated 6-azauridine (n6U), a uridine analogue with histidine-like N3 pKa, into the genomic HDV ribozyme active site by 2′-O-ACE oligoribonucleotide protection chemistry. The resulting ribozymes were analyzed for their ability to undergo the HDV ribozyme cis-cleavage reaction. Incorporation of n6U at nucleotide position 75 did not restore ribozyme function compared to the U75 mutant. This suggests that the HDV ribozyme reaction mechanism involves more than positioning of a neutral nucleobase at the active site and implies that the exocyclic amino group of C75 participates in establishing the proper active site fold.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
