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Copyright UC Regents Davis campus, 2005 - 18. Alll rights reserved. May not be re-distributed without prior written consent of course instructor. | of 3 BIS 102 Name Ker Spring, 2018 Last J First K. Hilt Second Midterm Score (100): Lquations: pH = pK, + log {[b]/[a B (Ky) (Ky) =1x 10 Kyp=x¥Q-x) K,=x7y-x) pH = (pKa, }pKy,V2F=(qiq@’)/er — AG=AH-TAS pK,’s of amino acid side chains: D (3.9), E (4.2), H (6.0), C (8.3), Y (10.1), K (10.5), R (12.5) pK, of amino acid a-COOH (2.1); pK, of amino acid &-NHs' (9.6) PK, of oligopeptide N-terminus (7.4); pK, of oligopeptide C-terminus (3.6) pK, of NH, = 9.26 (10 pts.) A protein was completely digested with trypsin and an internal peptide (i.e. not derived from the N- or C-terminals) was purified. Determine its sequence from the following information: a) amino acid analysis yields one mole of E, T, P, 8, W, F, K, and R per mole of peptide; b) treatment of the intact peptide with Sanger’s reagent, followed by acid hydrolysis, giveyDNP-S] c) treatment of the intact peptide with chymotrypsin yiclds a tripeptide containing K, T, and F; a tetrapeptide containing P, S, F, and R, and free W; d) the tripeptide. in part c, yields DNP-T afler reaction with FDNB and acid hydrolysis. Note: trypsin will not cleave on the carboxyl s} amino group) is P. le of R or K if the next amine acid (donating the Chaymeok pe ty eon \ ie Give the one-letter sequence of the peptide here: S- @-P — F-W - fon e-Kw kink tn @ DNe-T veverds, cleavage 2. (5 pts.) Which one of the following sequences is most likely to be involved in a a-helix? Circle the letter, i.e. a, b, c, d, or e of the correct answer. a) E-K-BAD-F oe C) E-G-F-V-A d) L-P-M-F-A °) A-M-$-Y-D 3. ( pts.) — Predict how the following environmental changes will affect the pK, of an E residue ina protein (circle the correct arrow): a) a H residue in the same protein is brought into close proximity pKa wv) b) the E side chain shifts from the outside of the protein to a nonpolar site at pK, (th c) an R residue in the same protein, that was close, moves away. pK, 4. (10 pts.) For question #3b above, give a detailed explanation of how you came to that conclusion. The inbevieor of ae grotein, \s nonpolar, voile Macrmedayanicodlly Savers no chawrie ow the side chat of E, For ek to be the, eure, Ye Con rh & netda 40 avab a WT to became cootl. 
