ALPPHA HELIX - with another chain that runs in the same or opposite direction Once again the hydrogen bonding involves the C=O group of one peptide

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
ALPPHA HELIX Imagine the polypeptide backbone as winding in a coil on the surface of a cylinder, with the side-groups protruding from the cylindrical surface. The a helix is stabilized by hydrogen bonds formed between the C=O group of one peptide bond and the NH group of the peptide bond four residues farther along the polypeptide chain. So, one turn of helix for ~ every 4 amino acids. Remember, interactions are not between side chains in this case. In fact if reactive side chains are present in the polypeptide this will interfere with the helical structure. Polyglycine which has only H as an R group forms an helix its entire length. See Figure in Text The alpha helix is a common component of protein secondary structures. Individual segments of alpha helix may be quite short. beta sheet A polypeptide chain can be extended into a sheet-like structure by hydrogen bonding
Background image of page 1
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: with another chain that runs in the same or opposite direction. Once again, the hydrogen bonding involves the C=O group of one peptide bond and the NH group of another. Beta-sheet structure. See Figure in text As well as occurring between two different polypeptide chains, this type of structure can be formed between two sections of a single polypeptide chain arranged so that the adjacent regions are in reverse orientation. Discuss principle of parallel vs anti-parallell Tertiary Structure Refers to the organization in three dimensions of all the atoms in the polypeptide chain, including the R groups as well as the polypeptide backbone. In a protein consisting of a single polypeptide chain, this level describes the complete structure. Proteins can be divided into two general types on the basis of their tertiary structure:...
View Full Document

This document was uploaded on 11/03/2011 for the course BIOLOGY MCB2010 at Broward College.

Ask a homework question - tutors are online