BIO130H1 Lecture Notes - Lecture 4: Alpha Helix, Coiled Coil, Opioid Peptide
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Note: the order of the aa"s is just as important as their presence e. g. leu-enkephalin is a natural opioid peptide which down modulates the perception of pain. If you change the order of the aa sequence, the pentapeptide would have no function in the body. The alpha helix: example of secondary structure, found in skin, hair, the r groups are not involved in hydrogen bonding, alpha helix vs dna helix, alpha helix is single stranded, whereas the dna helix is double stranded. In the alpha helix, the r groups are facing outwards. Another super secondary structure recognition helix: recognizes bases, found in the major groove, helix-turn-helix dna binding protein, 2 alpha helices joined by a short chain of aa (the turn) Tertiary structure rhodopsin: 3d overall structure of a protein, held together by, hydrophobic forces, non-covalent bonds, covalent disulphide bonds, tertiary structure is predictable by the primary structure (aa sequence, tertiary structure is dynamic.