Berg et al fig 242 tendency for secondary structure

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Unformatted text preview: ochemistry, 4th ed.) Loop Turn β turns (reverse turns) •  Nearly one ­third of residues are in turns or loops •  β ­turn is a four ­ residue region characterized by H ­bond between C=O of residue 1 and H ­N of residue 4 •  not all amino acid residues found in β ­turns due to steric constraints •  Many conformaHons possible at res. 2 and 3—different turn types Gly and Pro are quite common in turns. Why? Loops •  No regular periodic structures or parHcular paPerns of angles and hydrogen bonds—loops aren’t really secondary structures •  Longer “excursions” of backbone than simple reverse turns •  Usually at surface of protein •  Can be floppy (unstructured) •  Omen mediate interacHons with other molecules Loops in anHbodies: structure of one domain of an anHbody polypepHde (red loops involved in binding anHgen; flexible structures in loops interact with anHgen). Berg et al., Fig. 2 ­42 Tendency for Secondary Structure •  Depends on the properHes of AA •  Branched side chai...
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This test prep was uploaded on 02/25/2014 for the course BIOC 462A taught by Professor Ziegler,baldwin during the Spring '08 term at University of Arizona- Tucson.

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