CHEM 3P93 Lecture Notes - Lecture 2: Phosphodiester Bond, Hydrolysis, Electrophile
Document Summary
Stability of phosphate diesters (and that of dna/rna) Half life of hydrolysis at ph 7, 25(cid:1)c. Half-lives of hydrolysis in 1 m naoh, 25(cid:1)c. Answer lies in the mechanism for the hydrolysis. The intermediate is doubly negatively charged, and is more sterically congested than that of ester and amide hydrolysis. Of interest: half-life for dna from bone to degrade: 521 years (proc. Due to the presence of 2"-oh as a nucleophile that is in close proximity (proximity effect) to the electrophile (phosphodiester), intramolecular reactions become much more effective. Acceleration of hydrolysis of dna/rna by nucleases: up to 1018-fold rate acceleration: coli dna polymerase i. Beese and steitz, embo j 1991, 10, 25. Basic nucleic acid structure, chapter 5 voet & voet. Three components of nucleic acids: nucleobases, pentose sugar, and phosphate. Some tautomers were suggested to be responsible for spontaneous point mutations in dna (nature 1976, 263, 285 289)
