615 or 660? Average MW of a DNA base pairAverage MW of a DNA bas
Posted 21 November 2012 - 02:05 AM
Thanks for help
Doležel J, Bartoš J,Voglmayr H, Greilhuber J (2003). "Letter to the editor: Nuclear DNA Content and Genome Size of Trout and Human". Cytometry 51A (2): 127–128. doi:10.1002/cyto.a.10013. PMID 12541287.
Posted 21 November 2012 - 07:15 AM
But thanks for your reply
Posted 21 November 2012 - 02:41 PM
GC: 347.2207+307.1966-(4x1.0079+2x15.9994)-(2x1.0079)= 616.3711
AT: 331.2213+322.2079-(4x1.0079+2x15.9994)-(2x1.0079)= 615.383
Note that this reflects the loss of water and a proton from both strands.
Without accounting for the masses lost from the 2 waters or the 2 protons lost from the backbone phosphate, the masses end up being 654.4173 for GC and 653.4292, so an average of 653.9233. So I could see your original estimate of 660 roughly matching the value obtained if you just counted DNA as if it were a chain of AMP, TMP, GMP and CMP.
So yeah, that paper looks right.
edit: I have found references to masses of DNA with salt bound giving an average mass for a base-pair at roughly 660, so perhaps that's where your number comes from.
Edited by John Forsberg, 21 November 2012 - 02:42 PM.