BIBC 100 MT Fa'06 Montal

BIBC 100 MT Fa'06 - BIBC 100 Midterm Exam 1(24 Draw a diagram of the quaternary structure of immunoglobulin IgG including disulfide bridges and

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BIBC 100 Midterm Exam 1. (24) Draw a diagram of the quaternary structure of immunoglobulin IgG including disulfide bridges and antigen recognition site. (8 pts) a. Define a disulfide bridge. (4 pts) Covalent bond between Sulfur atoms on two different Cys residues of a polypeptide chain or between chains, stabilizes protein structure when under oxidizing conditions b. How many subunits make up an active molecule and what is the motif of the protein fold? (6 pts) 2 LC + 2 HC = heterotetramer fold is distorted β -barrel c. The antigen is recognized by what part of the IgG; which part of that motif specifically? (4 pts) Variable region of LC and HC recognition at the loops of the -barrel d. What is the smallest unit of an antibody molecule that can retain the specificity of the whole molecule? (2 pts) Fab fragment
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2. (14) Draw the helical wheel, and plot the eleven-residue α -helix: N-term…F-S-W-I-L-S-A-A-R-T-M…C-term(8 pts) a. Label the regions of the α -helix that are polar and hydrophobic. (4 pts) b. How many peptide bonds does this α -helix have? (2 pts) 10 3. (8) Identify the groups in a protein that can form hydrogen bonds or electrostatic bonds with an R side chain at pH 7.5. (8 pts) Asp (D) or Glu (E) — electrostatic bonds Asn (N) or Gln (Q) — Hydrogen bonds
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4. (2) Glycine is a highly conserved amino acid in the evolution of proteins; why? (2 pts) Because the R group is a proton the lack of steric hindrances allows unusual main chain conformations. 5. (2) Proline is often found in β -hairpin structures; why? (2 pts) Proline has a bent amino acid backbone that fits well into short loops. 6. (16) Draw a Zn
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This note was uploaded on 09/18/2010 for the course BIBC 100 taught by Professor Montal during the Fall '06 term at UC Merced.

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BIBC 100 MT Fa'06 - BIBC 100 Midterm Exam 1(24 Draw a diagram of the quaternary structure of immunoglobulin IgG including disulfide bridges and

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