Protein-Carbohydrate Interaction Fundamental Considerations

Nikki F. Burkhalter, Sarah M. Dimick, and Eric J. Toone 

Throughout, we endeavor to relate energetic issues directly to protein-carbohydrate interaction. We stress, however, that a tremendous body of literature pertaining to the very issues central to protein arbohydrate interaction exists in the context of other binding systems. Where appropriate, we draw on the lessons and experience of these adjacent disciplines in our consideration of the biophysical aspects of protein-carbohydrate interaction. 

Two species combine to form a complex in water if the sum of the intermolecular forces between them more than olfsets the sum of the loss of favorable interactions with solvent and any unfavorable interactions that develop between solutes during complex formation. Collectively the interactions between non-bonded species are referred to as cohesive forces, defined as those forces lost when the species are transferred to infinite separation in the gas phase. While it is common to classify chemical forces as covalent or non-covalent, the interactions are fundamentally the same only the magnitude of the interactions varies. Cohesive, non-specific forces are weak compared to covalent interactions typically we consider cohesive forces as those forces with strengths less than 1% of covalent bond strengths. We will see, however, that this definition is somewhat arbitrary and in fact a continuum of interaction energies exists. 

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