MBB 222 Study Guide - Midterm Guide: Leucine Zipper, N-Terminus, C-Terminus
20 Dec 2018
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Recognize the n-terminus and c-terminus of a polypeptide, and know the convention which is to write sequences from n to c. Describe the flexibility of the polypeptide chain in terms of and . Be able to recognize and describe -helices, -sheets and -turns, including their hydrogen bond patterns, the general location of the side chains in these secondary structures. Secondary structures are stabilized by hydrogen bonding, between main chain atoms (i. e. , not side chains). Thus, they are somewhat independent of the amino acid sequence. Type i and type ii turns differ in the orientation of the peptide plane between the second and third amino acid residues in the turn. a. Structure of a type i turn showing that the carbonyl oxygen is oriented inward. b. Structure of a type ii turn showing that the carbonyl oxygen is oriented outward. The carbons are numbered relative to the amino-terminal residue (c 1).
