CHARMM22 parameter set

The approach used in the parameterisation procedure means that once a force-field has been developed, it can only be used together with the selected water model. In principle, use of the Charmm22 parameter set with water models other than TIP3P may lead to inconsistencies because the water-protein and protein-protein intermolecular parameterisation may not be well balanced. However, whether this is actually the case has not yet been systematically investigated. 

Our Poisson-Boltzmann calculations are currently carried out with the atomic charges and radii of the PARSE parameter set, developed by Honig et al. or the CHARMM22 parameter set. ° The PARSE parameter set is attractive because when used with a solvation model based on the PB equation, it yields accurate solvation energies for a variety of small molecules. The CHARMM parameter set has the advantage of including parameters for more molecules and is also more easily accessible. Other possible charge/radii sets are from CVFF and OPLS. Use of nonstandard sets also has been reported. 

While not a complete list, a number of parameter sets appropriate for protein studies may be found in the following references.Finally, it should be noted that the intimacy of the author with the CHARMM22 all-hydrogen protein parameter set excludes a totally unbiased presentation of the aspects of protein force fields discussed below. 

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