Hello.
which one have more hydrogenic bond,alpha helix or beta sheet?
iappreciate your comments.
It is always intramolecular H-bonding stronger than intermolecular ones.
In contrast to the alpha helix, hydrogen bonds in beta sheets form in between N-H groups in the backbone of one strand and C=O groups in the backbone of the adjacent strands. This is the main difference between Alpha Helix and Beta Pleated Sheet.
In an α helix, the carbonyl (C=O) of one amino acid is hydrogen bonded to the amino H (N-H) of an amino acid that is four down the chain. (E.g., the carbonyl of amino acid 1 would form a hydrogen bond to the N-H of amino acid 5.) This pattern of bonding pulls the polypeptide chain into a helical structure that resembles a curled ribbon, with each turn of the helix containing 3.6 amino acids. The R groups of the amino acids stick outward from the α helix, where they are free to interact.
In a β pleated sheet, two or more segments of a polypeptide chain line up next to each other, forming a sheet-like structure held together by hydrogen bonds. The hydrogen bonds form between carbonyl and amino groups of backbone, while the R groups extend above and below the plane of the sheet. The strands of a β pleated sheet may be parallel, pointing in the same direction (meaning that their N- and C-termini match up), or antiparallel, pointing in opposite directions (meaning that the N-terminus of one strand is positioned next to the C-terminus of the other).
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