BCH 261 Lecture Notes - Lecture 5: Aromaticity, Nucleobase, Signal Transduction
6 Mar 2017
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Neutral at ph = 7: sensitive to ph changes. *** carbon-h bonds are not good donors or acceptors. Tautomers: isomers of each nucleobase that differs only in the position of the hydrogen and double bonds. Guanine, thymine, cytosine and adenine can undergo conversion between keto and enol (tautomeric forms) Absorption of uv light at 250-270 nm. Excited states of common nucleobases decay rapidly via radiation-less transitions: effective photoprotection of genetic material, no fluorescence from nucleic acids. Joining the base to the pentose- the n-gycosidic bond: The pentose ring is attached to the nucleobase via a n-glycosidic bond. The anomeric carbon of the sugar is in beta configuration. It forms a bond with position nitrogen 1 in pyrimides and position nitrogen 9 in purine. Joining the phosphate to the pentose- the phosphoester bond: Connection between two monomer units in nucleic acid.
