We have shown (J. Phys. Chem. A 2004, 108, 10923; 2007, 111, 5300) that the (CD alpha)-D-alpha stretch frequency, nu(CD), can discriminate between uniform alpha(R), beta, and polyproline II conformations of isolated peptides. Similar results for such peptides to which explicit waters are hydrogen bonded exhibit shifts in v(CD) from those of the isolated structures. We demonstrate that the main source of these frequency shifts is the formation of C-alpha-D-alpha center dot center dot center dot O hydrogen bonds to water. Taking into account C-H center dot center dot center dot O (water) hydrogen bonding, together with the traditional bonding of peptide groups to water, can be expected to increase our understanding of the interaction of proteins with their aqueous environment.