Carbon-oxygen bonds electrostatic repulsion

All protein atoms except hydrogens bonded to carbon were explicitly represented. Positions of polar hydrogens were calculated on the basis of coordinates of the heavier atoms (5) and standard geometric constraints (14). The non-bonded energy for the interaction of the water molecule and the protein was calculated as a sum of electrostatic and 6-12 Lennard-Jones attractive and repulsive contributions for the three atoms of the water molecule and all atoms of the protein within 6 X of the water oxygen s center. Empirical parameters were used for the 6-12 potentials (15,16,17), partial atomic charges were values obtained with molecular orbital calculations (1 ) for hydrogen-bonded interactions modified 6-12 parameters were used (18). 

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