drake5 - Biomolecules: Peptides and Proteins Lecture 5,...

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Biomolecules: Peptides and Proteins Lecture 5, Medical Biochemistry
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Lecture 5 Outline Overview of amino acids, peptides and the peptide bond Discuss the levels of protein structure Describe techniques used for analysis of proteins
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Planar nature of the peptide bond. The partial double bond characteristic prevents free rotation around the C-N bond; keeping it in the same plane with the attached O and H atoms. These planar bonds can pivot around the shared C α atom
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Levels of Protein Structure
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Protein Structure Levels PRIMARY: the linear sequence of amino acids linked together by peptide bonds SECONDARY: regions within polypeptide chains with regular, recurring, localized structure stabilized by H-bonding between constituent amino acid residues
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Protein Structure Levels (cont) TERTIARY: the overall three- dimensional conformation of a protein QUATERNARY: the three-dimensional conformation of a protein composed of multiple polypeptide subunits THE PRIMARY AMINO ACID SEQUENCE IS THE ULTIMATE DETERMINANT OF FINAL PROTEIN STRUCTURE
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Ex: INSULIN Disulfide bonds Form between two intra- or interchain cysteine residues, product called cystine - Stabilizes/creates protein conformation - Prevalent in extracellular/ secreted proteins
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Stabilizing Forces 1. Electrostatic/ionic 3. Hydrophobic interactions 2. Hydrogen bonds 4. Disulfide bonds
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2 o Structure: α -helix each oxygen of a carbonyl group of a peptide bond forms a H-bond with the hydrogen atom attached to a nitrogen in a peptide bond 4 amino acids further along the chain; very stable structurally; prolines will disrupt helix formation
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End-on view of α -helix
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This note was uploaded on 12/16/2011 for the course BIOLOGY 101 taught by Professor Mr.wallace during the Fall '11 term at Montgomery College.

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drake5 - Biomolecules: Peptides and Proteins Lecture 5,...

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