Peptides hydrogen bond between

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). 

Pleated p sheet (Section 27.19) Type of protein secondary structure characterized by hydrogen bonds between NH and C=0 groups of adjacent parallel peptide chains. The individual chains are in an extended zigzag conformation. 

FIGURE 6.5 A hydrogen bond between the amide proton and carbonyl oxygen of adjacent peptide groups. 

The secondary structure of a protein is determined by hydrogen bonding between CDO and N—H groups of the peptide linkages that make up the backbone of the protein. Hydrogen bonds can exist within the same protein... 

Sapse, A.-M., L. M. Fugler, and D. Cowbum. 1986. An Ab Initio Study of Intermolecular Hydrogen Bonding Between Small Peptide Fragments. Int. J. Quantum Chem. 29, 1241-1251. 

It is the sequence and types of amino acids and the way that they are folded that provides protein molecules with specific structure, activity, and function. Ionic charge, hydrogen bonding capability, and hydrophobicity are the major determinants for the resultant three-dimensional structure of protein molecules. The a-chain is twisted, folded, and formed into globular structures, a-helicies, and P-sheets based upon the side-chain amino acid sequence and weak intramolecular interactions such as hydrogen bonding between different parts of the peptide... 

In balance, the small decrease in enthalpy (AH < 0) is more than offset by a large decrease in entropy (AS < 0) so that the overall reaction is unfavorable. Thus, one would not expect to see the formation of single hydrogen bonds between two peptides in water. This is what is found. 

Figure 2.7 (a) The P-bend or p-turn is often found between two stretches of antiparallel p-strands. (b) It is stabilized in part by hydrogen bonding between the C=0 bond and the NH groups of the peptide bonds at the neck of the turn... 

Addition of 81-SH to 80-SS-81 led to formation of the homodisulfide compounds and an equilibrium, with an exchange constant of 1.8, was established. The presence of the templating (D)Pro(L)Val(D)Val tri-peptide in this mixture, shifted the equilibrium dramatically and the formation of the homodisulfide 80-SS-80 was amplified with a Keq=32. Since the templating tri-peptide was supported on polymer beads, the isolation of receptor 80-SS-80 (in 97% purity) was achieved easily by extraction of the beads. The formation of multiple hydrogen bonds between the template and the components of the DCL, led to the isolation of the best possible receptor available from the building blocks present in the equilibrated mixture. 

Figure 11.2 The secondary structure of proteins. The simplest spatial arrangement of amino acids in a polypeptide chain is as a fully extended chain (a) which has a regular backbone structure due to the bond angles involved and from which the additional atoms, H and O, and the amino acid residues, R, project at varying angles. The helical form (b) is stabilized by hydrogen bonds between the —NH group of one peptide bond and the —CO group of another peptide bond. The amino acid residues project from the helix rather than internally into the helix.

Tight turns were first recognized from a theoretical conformational analysis by Venkatachalam (1968). He considered what conformations were available to a system of three linked peptide units (or four successive residues) that could be stabilized by a backbone hydrogen bond between the CO of residue n and the NH of residue n + 3. He... 

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