341lecture05sept18sakai

341lecture05sept18sakai - Cell Biology 341 Last lecture:...

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Cell Biology 341 Friday, Sept. 18, 2009 Today: Examples of quaternary structure Finish chapter 2 on thermodynamic limitations on enzyme activity last section of chapter 3 on regulation of enzymes See your DVD for chapter 3 videos, especially α helix, β sheet, disulfide bonds, coiled-coil, SH2 domain, lysozyme I and II, oligomeric proteins, EF-Tu and Safe Crackers Also see video 25.2 on antibody structure Last lecture: chapter 3 the primary structure of a protein is the sequence of amino acids All four types of noncovalent forces participate in determining the 3- dimensional structure of a protein Nonpolar residues are usually found in the interior of a globular protein due to hydrophobic forces 2200 α helix and β sheet are secondary structures formed by hydrogen bonding between peptide bond atoms The R-groups contribute to tertiary structure Coiled-coil structures contain amphipathic α helices Quaternary structure occurs in proteins with more than one polypeptide chain
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The complete 3-dimensional conformation is called the tertiary structure . Tertiary structure includes the interactions of the amino acid side chains This enzyme breaks a peptide bond of another protein in the red active site Only proteins that contain 2 or more polypeptide chains have quaternary structure Neuraminidase is a tetramer of 4 identical subunits Figure 3-12, 21 Tamiflu inhibits the influenza virus neuraminidase from cleaving sialic acid from the surface of infected cells
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quaternary structure have two or more subunits (2 = dimer) Most tertiary and quaternary structures are dependent on the four types of noncovalent interactions One exception: proteins that are secreted from cells (extracellular) often contain covalent disulfide bonds for stability. These
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This note was uploaded on 12/05/2009 for the course BIO 341 taught by Professor Noris during the Fall '09 term at Rhode Island.

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341lecture05sept18sakai - Cell Biology 341 Last lecture:...

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