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help for DNA to RNA

huizenga at Frodo.MGH.Harvard.EDU huizenga at Frodo.MGH.Harvard.EDU
Tue Nov 8 17:57:32 EST 1994


In post 1778 Sreyas is looking for experiments which i think could possibly
transform RNA into DNA (if that is incorrect sorry).  anyways to my
knowledge all modern day organisms use a ribonucleotide reductase enzyme
which i believe is B12 dependent to transform biotically synthesized RNA
into DNA.  Inother words modern day organisms to my knowledge all
start with ribonucleotide (not strand) molecules and reduce these 
into deoxynucleotides.  The fact that there are no known organisms which
synthesize deoxyribonucleotides denovo so to speak (all coming from ribos
has been invoked as evidence that there most likely was a 
ribonucleotide reductase activity existent in the RNA world.  Meaning
that at some point in an RNA world (no protiens,just RNA catalysts) 
that there existed an RNA molecule which would actually act as an RNAS
ribonucleotide reductase.  This molecule (if we stretch the evolutionary
arguement) most likely would have worked on mononucleotides not oligo
nucleotides.  Kind of a babbling answer,sreyas, to say that rather
then attempting to transform oligonucleotides RNAto DNA, you might
think about looking at some sort of experiment involving, mononucleotides,
v B12 and some sort of invitro selection experiment in which you 
look within a random pool of oligonucleotides for one that catalyses
the reaction you want (see Bartel and Szostak, (1993) 261, 141
pg 1411) tha t is supposed to be science (1993) vol 261, pg1411.
anyways, just my two cents worth and good luck with your thesis
					David



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