Why 5'->3' and not 3'->5' ?
Jeffrey A. Cohlberg
cohlberg at csulb.edu
Tue Mar 31 16:44:48 EST 1998
> Yes, but why is the triphosphate group not off the 3' end? :)
> You evolutionist continually ignore the obvious design.
It may be relevant that nucleoside-3'-phosphates exist in solution as an
equilibrium mixture of 2' and 3' isomers. They interconvert through a
nucleophilic attack of the free hydroxyl on the phosphorus atom, with
the other hydroxyl as a leaving group. Nucleoside-3'-triphosphates, if
they existed, would undergo the same type of isomerization. On the
other hand, a nucleoside-5'-phosphate (or triphosphate) does not undergo
this sort of isomerization. One could argue that this fixed structure
would be better suited to be a precursor for evolution of nucleic acids.
Jeffrey A. Cohlberg, Professor
Department of Chemistry and Biochemistry
California State University, Long Beach
1250 Bellflower Blvd.
Long Beach, CA 90840
phone (562) 985-4944 fax (562) 985-8557
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