Subject: CFF91 and Carbohydrates - Summary

From: [email-masked] (Jeffrey L. Nauss)
Date: Fri, 8 Mar 1996 16:03:22 -0500

Sometime ago, I posed the following question:

> The tutorial for InsightII optimizes an ligand for lysozyme using
> the CFF91 forcefield.  Has this forcefield been optimized for
> carbohydrates now.  If so, is there are reference available
> supporting the use of CFF91 with carbohydrates?

The quick answer is no.  Neither CFF91 nor its successor CFF93 are
parameterized for carbohydrates.  CFF95, however, is reported to be
parameterized for them.  Unfortunately, CFF95 is only available as a
separate purchase.  I will let you call your own Biosym/MSI sales
representative for the price.  The use of CFF91 in the insightII 95.0
tutorial was strictly for demonstration purposes.

An edited version of the individual replies is included below.  The
complete mail messages are available at
http://www.che.uc.edu/~nauss/cff91_carbohydrates.html

						Jeff Nauss

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From: "Dr. James Brown" <[email-masked]>

	The answer is no, CFF91 was no parameterized against carbohydrates.

From: [email-masked] (Marvin Waldman)

	The new CFF95 forcefield available from Biosym/MSI has
	parameters for carbohydrates (as well as peptides, nucleic
	acids, organics, metal ions, ...).  CFF95 is available as a
	separately sold product from Biosym/MSI.  Please contact your
	local sales representative for information on how to purchase
	this product....  Cff91 deals with carbohydrates by
	recognizing the oxygens and carbons using either alcohol or
	ether type parameters for which it is well parameterized.  The
	cff95 forcefield is specifically parameterized for
	carbohydrates with special atom types assigned for this
	functional group.  This (together with the functional form
	which includes important cross terms such as bond-torsion)
	enables cff95 to give a highly accurate representation of the
	conformational energetics of carbohydrates, in particular the
	anomeric effect is well treated which is not the case for
	cff91.

From: David Renouf <[email-masked]>

	Biosym have informed me that CFF95 is the version that has
	these parameters and that CFF95 has to be purchased in
	addition to the supplied forcefields.

-- 
						Jeff Nauss

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*  UU    UU             Jeffrey L. Nauss, PhD                         *
*  UU    UU             Director, Molecular Modeling Services         *
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