1 - TA Christine Feng [email protected] Section Mon 4-5...

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Unformatted text preview: TA: Christine Feng [email protected] Section: Mon 4-5 Center 205 OH: Wed 11-12 Geisel S&E Amino Acids Hydrophobic Non ­Polar: A Vegas PIMP(he) Likes Girls Polar Charged: [H]K RED Polar Uncharged: All others! Proteins Primary: AA sequence via peptide bond (rigid & planar) with free rotation about bonds to C(alpha) Peptide Bond Phi/psi Ramachandran plots *** glycine Secondary: fold so all hydrophilic groups can H bond to adjacent groups Alpha helix: wrap around imaginary axis with R groups sticking out (Right handed) Glycine too flexible so not stable, see Prolines in 1st turns (introduce kinks) Beta sheet: zig ­zag structure with H bonds between project segments not necessarily adjacent in primary structure, R groups point up or down out of sheet plane Tertiary: 3D arrangement in space, can be shown with ribbon, mesh, surface contour, etc Disulfide Bonds – cysteine S—S (+ reducing agent = break into –SH HS ­ ­) Quaternary: 3D structure of multi ­subunit proteins (prosthetic groups, polypeptides, etc) Water  ­ Hydrogen bonds: H ­ ­ ­[electronegative atom] i.e. NaCl in H2O  ­ Hydrophilic: dissolves easily in water, H2O ­ ­ H2O interactions replaced by H2O—solute interactions  ­ Hydrophobic effect: association of nonpolar groups with each other, driven by H2O molecules seeking most energetically favorable state (displace ordered H2O increase entropy) Van der Waals: far = attractive; close = repulsion Papers Why? Hypothesis How? Methods What? Findings So What? Importance of results ...
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