Mg2+ parameters

Aaron s_aarono at EDUSERV.ITS.UNIMELB.EDU.AU
Tue Mar 12 20:17:06 EST 1996


> Does anyone have any suggestions for parameters for Mg2+ using  the
> parhcsdx.pro forcefield?  We have been trying the parameters from
> parallhdg.dna  (eps 0.2 and sigma 2.8509) but this does not seem to work
> very well for a Mg bound at an active site and surrounded by waters. The Mg

In the file available at 

http://xplor.csb.yale.edu/tutorial/toppar/parameter.elements

the following are given for Mg:
 !                  eps     sigma       eps(1:4) sigma(1:4)
 !                  (kcal/mol) (A)
 !                  ---------------------------------------
 NONBonded  MG         .0450 2.564      .0450    2.564

> keeps getting refined out of density and the refined water-Mg distances are
> too long. Also, should a charge of +2 be used on the Mg or should it be
> kept neutral?  Is there anything else that needs to be defined?

Would introducing charge bias the refinement because of the
strong E(ELEC) interaction?

Hope this helps,

Aaron.



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