BIOLOGY 2B03 Lecture Notes - Lecture 1: Amphiphile, Disulfide, Protein Structure
1 Sep 2020
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Document Summary
Secondary structure: conformation of a portion of the polypeptide due to local chemical interactions that will eventually fold a protein. Result of the polypeptide backbone interactions (n-terminus amino group and c-terminus carboxyl group) and does not involve any r side group interactions. Periodic folding of polypeptide chain into distinct, conserved, geometric arrangements. Beta-sheet: planar structure, composed of alignments of two or more beta strands. Turns/loops: connectors (bends in the polypeptide backbone) that lie between alpha helices and beta sheet strands. Secondary structures are defined by the patterns of hydrogen bonds occurring between non- variable side chains, the amino and carboxyl groups. Carbonyl oxygen of each peptide bond in the helix is hydrogen bonded to the amide hydrogen of the amino acid four residues away towards the c-terminus. These alpha helices are found with the exact same pattern and exact same shape/structure in all proteins because the variable r side groups are not involved in the formation of this structure.
