Bidentate hydrogen bonds

Figure 6.8 Proposed modes of action of hydrogen-bonding catalyst 16 Bidentate hydrogen bonding coordination of the zwitterion derived from Michael-type DABCO attack to methyl acrylate (1) and Zimmerman-Traxler transition state for the reaction of methyl acrylate with benzaldehyde (2).

Figure 10. Bidentate hydrogen bonding between multidentate anions and the guanidinium moiety.

In the model cAPK with bound staurosporine inhibitor, the lactam amide group of the inhibitor functions as a bidentate hydrogen bond donor-acceptor... 

The use of the 6-amino group and N1 nitrogen of the purine base to model the pharmacophore, as seen with staurosporine, is not possible in two other adenine-type inhibitors. Both isopentenyl adenine, a nonspecific inhibitor of protein kinases, and olomoucin, a more specific inhibitor of Ser/Thr protein kinases, are modified only at the 6-amino group position. Thus, bidentate hydrogen-bond formation as seen in the ATP purine base is not possible. Furthermore, there are inhibitors that do not contain the chemical structure of adenine, for example des-chloro-flavopyridol, a potent inhibitor of cdc-2 cell cycle kinase. 

If the best donors and acceptors couple, and the common aminopyrimidine bidentate hydrogen bonds form, then the following acentric structure is conceivable. 

Bidentate hydrogen-bonding interaction with an aspartate sidechain and the 3 and 4 position hydroxyl groups of galactose... 

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