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Unformatted text preview: s. In solution, there are ~10.5 base-pairs per turn. To find whether the two strands are parallel or antiparallel, Kornberg
synthesized DNA enzymatically from labeled nucleoside triphosphates
1. Synthesize DNA from a mixture of ATP, GTP, CTP & TTP in which one of the
four nucleotides is labeled with 32P in the α position (e.g., pppA).
2. Hydrolyze the DNA with a DNase that releases the 3’-mononucleotides.
3. Measure the amount of 32P transferred to various nucleotides.
pppA + pppT
+ pppG + pppC DNA polymerase 5’ ... pGpApTpCpApGp ... 3’
3’ ... pCpTpApGpTpCp ... 5’ ... Gp + Ap + Tp + Cp + Ap + Gp ... H2O
DNase ... Cp + Tp + Ap + Gp + Tp + Cp ...
4. Repeat the experiment starting with the label in other nucleotides.
If the strands are antiparallel: A C = G T and A G = C where the arrows indicate the transfer pf the radioactive phospate/
What if the chains are parallel? High-resolution structures of small
DNA molecules have been obtained by
x-ray crystallography and NMR NMR
NMR structure of a duplex DNA
dodecamer in the DNA-binding
site of an interferon promotor.
J. R. Huth et al., Nature Struct. Biol.
4: 657 (1997). 2eze.pdb The two strands of the double helix
separate reversibly at...
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This note was uploaded on 02/17/2012 for the course CHEM 212 taught by Professor Staff during the Fall '10 term at Rutgers.
- Fall '10