hi... we're using nmode to estimate the entropy of a dna sequence with a
carcinogen binded. we took out the structure from dynamics trajectory, then
do minimization exclude water and ions but using a 4r dd to mimic solvent.
we found that after minimization using a drms of 0.0001 the structure is
extremely distorted to a kind of denatured state, especially at the end the
dna (the base paring are distorted...). it has a rms of 2.7 comparing to the
original structure from dynamics. we think this is an unrealistic state. we
tried to use a less rigorous way to do minimization using drms of 0.01 and
0.1, it turns out that the structure is perfectly well with a rms of 0.7 and
0.4 comparing to the original dynamics structure. but the entropy is kind of
sensitive to this. we want to find minimized structure which is similar to
the dynamics structure, so that we can estimate the entropic term of free
energy of the molecule. i would like to know what the mathematical error
will be if we use a drms of 0.1 or 0.01 in the minimization, then do normal
mode analysis. or is it reasonable to use a less rigorous criteria in
minimization, but to get a much more reasonable or similar structure
comparing to the dynamics structure to get better estimation of entropy.
thanks very much for any help... frank
______________________________________________________
Get Your Private, Free Email at
http://www.rosswalker.co.uk/adsense_alternatives/
Received on Thu Mar 16 2000 - 07:43:50 PST
