Side hydrogen bonding

Figure 6 opposite) Hydrogen bonding between polypeptide main-chain CO and NH groups (a) formation of an a helix (b) formation of an antiparallel sheet and (c) formation of a parallel p sheet. The formation of P sheets occurs through side-by-side hydrogen bonding between -strands... 

Bruha A, Kincaid JR (1988) Resonance Raman studies of dioxygen adducts of cobalt-substituted heme proteins and model compounds. Vibrationally coupled dioxygen and the issues of multiple structures and distal side hydrogen bonding. J Am Chem Soc 110 6006-6014... 

Recent work on the alkaline hydrolysis of protolytic esters has considered the possibility of hydrogen-bond formation between some ammonium groups and the carbonyl carbon of the ester, e.g. 28 (see section V.A.2). However, when such esters contain a rigid acetylenic group in the alcohol side, hydrogen bonding is prevented and hydro-... 

By using an effective, distance-dependent dielectric constant, the ability of bulk water to reduce electrostatic interactions can be mimicked without the presence of explicit solvent molecules. One disadvantage of aU vacuum simulations, corrected for shielding effects or not, is the fact that they cannot account for the ability of water molecules to form hydrogen bonds with charged and polar surface residues of a protein. As a result, adjacent polar side chains interact with each other and not with the solvent, thus introducing additional errors. 

Ammo acids with polar but nonwmzed side chains Among ammo acids with polar side chains serine is the smallest it is not much larger than alanine With a —CH2OH side chain serine participates well m hydrogen bonding and often occurs m regions of a peptide that are exposed to water... 

As a p hydroxy derivative of phenylalanine tyrosine has properties similar to those of phenylalanine plus the ability to engage m hydrogen bonding via its —OH group Asparagine and glutamine are not amines they are amides The side chains of both O... 

Fig. 3. (a) Chemical stmcture of a synthetic cycHc peptide composed of an alternating sequence of D- and L-amino acids. The side chains of the amino acids have been chosen such that the peripheral functional groups of the dat rings are hydrophobic and allow insertion into Hpid bilayers, (b) Proposed stmcture of a self-assembled transmembrane pore comprised of hydrogen bonded cycHc peptides. The channel is stabilized by hydrogen bonds between the peptide backbones of the individual molecules. These synthetic pores have been demonstrated to form ion channels in Hpid bilayers (71). 

Hydrophilic Groups. Water solubiUty can be achieved through hydrophilic units in the backbone of a polymer, such as O and N atoms that supply lonepair electrons for hydrogen bonding to water. SolubiUty in water is also achieved with hydrophilic side groups (eg, OH, NH2, CO2, SO3 ). 

Fig. 2. Protein secondary stmcture (a) the right-handed a-helix, stabilized by intrasegmental hydrogen-bonding between the backbone CO of residue i and the NH of residue t + 4 along the polypeptide chain. Each turn of the helix requires 3.6 residues. Translation along the hehcal axis is 0.15 nm per residue, or 0.54 nm per turn and (b) the -pleated sheet where the polypeptide is in an extended conformation and backbone hydrogen-bonding occurs between residues on adjacent strands. Here, the backbone CO and NH atoms are in the plane of the page and the amino acid side chains extend from C ...

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