Synthesis and Enzymic Hydrolysis of Oligoribonucleotides Incorporating 3-Deazaguanosine: The Importance of the Nitrogen-3 Atom of Single Conserved Guanosine Residues on the Catalytic Activity of the Hammerhead Ribozyme

✍ Scribed by Frank Seela; Harald Debelak; Lori Andrews; Leonid Beigelman

• Book ID: 102255219
• Publisher: John Wiley and Sons
• Year: 2003
• Tongue: German
• Weight: 223 KB
• Volume: 86
• Category: Article
• ISSN: 0018-019X
• DOI: 10.1002/hlca.200390222

✦ Synopsis

Abstract

Four base‐modified hammerhead ribozyme/substrate complexes were constructed in which single guanosine (1) residues were replaced by 3‐deazaguanosine (2) in the positions G~5~, G~8~, G~L2.1~, and G~12~. The base‐modified ribozyme complexes were prepared by solid‐phase synthesis of oligoribonucleotides employing the novel phosphoramidite 3 derived from 2. Phosphoramidite 3 carried a phenoxyacetyl group at the amino function and a diphenylcarbamoyl residue at the oxo group of the nucleobase. The 2′‐hydroxy group was blocked with a triisopropylsilyl residue. Kinetic analysis of the phosphodiester hydrolysis showed a moderate decrease of the ribozyme catalytic activity when the residues G~5~ or G~8~ were replaced by 3‐deazaguanosine and a 200‐fold decrease when G~12~ was substituted. A 6‐fold catalytic increase occurred when 3‐deazaguanosine was replacing G~L2.1~ in the loop region. The data indicate that the N(3) atom of compound 2, in particular at position G~12~ is critical for the ribozyme activity.