GRID Maps from a Small Molecule

The blue contours (C) in Fig. 1.9 were generated by the N3-i- cationic amine probe which makes good hydrogen bonds to the (red) carboxy oxygen atoms of the target. When generating these blue contours GRID takes account of the fact that 

It is important to give careful consideration to apparently small details in a GRID map. The carboxy group in Fig. 1.9 may appear to be symmetrical, but the blue contours are stronger round the oxygen at the bottom of the figure. This difference between the oxygens may be caused by two quite distinct influences  

The upper oxygen is closer to the cationic nitrogen N3-r of the leucine, and so the cationic N3-r probe may experience an unfavorable electrostatic repulsion when it is dose to the leudne nitrogen s cationic charge. 

The bottom oxygen in the figure is partly shielded from bulk water by the hydrophobic moiety (yellow spheres) of the target, and so its dielectric environment may tend to favor the electrostatic attraction of a cationic probe. 

To print a list of the teachers and colleagues who have helped me would occupy too much space here. My debt to all of them is immense, and is only matched by my gratitude to each one for their generosity, and to my wife for all her support 

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