logo.gif (3296 bytes)Introduction to Protein Structure

Hydrogen Bonding

Hydrogen bonding involves the interaction of a "non-bonded" (i.e. not covalently bonded) pair of electrons on one atom interacting with a hydrogen atom involved in a polar "H--X" bond.  In proteins "X" is almost always a nitrogen or oxygen.

The electronegativity of "X" relative to hydrogen causes the hydrogen atom to be electron deficient (this is sometimes shown as a partial positive charge, d+). A hydrogen bond is formed when this partially positive hydrogen is attracted to a lone pair of electrons on a nearby atom (again, in proteins this is almost always a nitrogen or an oxygen).

In proteins, X and Y are most commonly oxygen or nitrogen

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The group bearing the hydrogen is considered the hydrogen bond donor. The other group is considered  hydrogen bond acceptor.

Copyright 1998, 1999, 2007 by Frank R. Gorga;   Page maintained by F.R. Gorga;   Last updated: 12-Mar-2007