BIS 102 MT2 Fall 2010

BIS 102 MT2 Fall 2010 - lof3 BIS 102 Name KgJ Fall 2010...

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Unformatted text preview: lof3 BIS 102 Name KgJ Fall, 2010 Last First K. Hilt Second Midterm Score (100): Equations: pH = pK. + log {nu/[an <K.) (Kb) = 1 x 10'” Kb = x2/ (y-x) K. = My - x) pH = (pKal + pKa2)/2 F = (q1 qz) / e 1'2 AG = AH — TAS pKa’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) pKa of amino acid a-COOH (2.1); pKa of amino acid or-NHg,+ (9.6) pKa of oligopeptide N-terminus (7.4); pKa of oligopeptide C-terminus (3.6) pKa of NH4+ = 9.26 1. (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 fiom the following information: a) amino acid analysis yields one mole of E, T, P, S, W, F, K, and R per mole of peptide; b) treatment of the intact peptide with Sanger’s reagent, followed by acid hydrolysis, gives DNP-S; c) treatment of the intact peptide with chymotrypsin yields a tn'peptide containing K, T, and E; a tetrapeptide containing P, S, F, and R, and free W; d) the tripeptide, in part c, yields DNP-T after reaction with FDNB and acid hydrolysis. Note: trypsin will not cleave on the carboxyl side of R or K if the next amino acid (donating the amino group) is P. Give the one-letter sequence of the peptide here: 3 - R - P - E — VJ — T~ E - Si 2. (5 pts.) Which pg; of the following sequences is most likely to be involved in a a-helix? Circle the letter, i.e. a, b, c, or d of the correct answer. a) E-K-E-D-F @E-K—F—V—A c) E-G—F-V-A d) L—P-M-F-A 3. (9 pts.) Predict how the following environmental changes will affect the pKa of a E residue in a protein (circle the correct arrow): 4' 3 a) a H residue in the same protein is brought into close proximity +3 b) the B side chain shifts fi'om the outside of the protein to a nonpolar site inside 4' 3 c) an R residue in the same protein, that was close, moves away. pKaG Jr 4. (10 pts.) For question #3b above, explain how you came to that conclusion. +2 [5- W 5,; a w — in Mmag+mt {+5 5th m. The. nwpolar fiauafs Hg 0 wwaefls 111+ E 531701. chum Wait/1+5 +0 sfab \ l 2 a Hl'l ,n gala” +0 aniéb “Max. Hafiz, 4’3 QQAL Mve 4'5 20f3 Name 5. (5 pts.) This allosteric efi‘ector of Hb creates two salt bridges every time one effector binds. What is this effector and where does it bind in Hb? Be very specific. Limit your answers to the lines provided. BIS 102 Name of effector: Cl ‘ “7 we. 0L» SKLWH’ mcfl +1.; 2 0H“ oc-Sulawt‘rh Binding place: berm M Math“. 6. (8 pts.) This allosteric effector of Hb is the most important negative heterotropic allosteric effector. What is its name, where does it bind, and what is the experimental evidence that supports your assertion that it is the most important? Be very specific in your answers. Limit your answers to the lines provided. + 7. Name of effector: E?9 +' + 2. Binding place: No bet-ween M hue Experimental evidence: (mow! d BPS maul-s ‘m a \‘Ha binding chime fin,» Ozi’laai'isdm-l-OMELML, *3 ¢md cowl - “been i+$ 7. (25 pts.) Using the axes drawn below, carefully draw in the expected binding curves for the following situations. Label each curve with the appropriate letter of the situation, i.e. “a”, “b”, etc. a) Hb, pH 7.2 b) Hb, pH 7.6 c) Hb, pH 7.2 and 50% saturated with CO d) Hb, pH 7.6, where the C-terminal H of the B-subunit has mutated to an E e) Hb, pH 7.2, and 50% saturated with C02 100 % 02 Bound 100 0 p02 (torr) 8. (5 pts.) Explain why you drew the curve for part “d” of question #7 above, the way you did. What was yourreasoning? ‘H Mu+a+iw af, '4 +0 E «M- M C~4¢lem rw‘ns +W‘0 0"? “4?. 13 59.1)? bviiafia’ malt—int) H’ :49}, £0“ 02 4% “fiat. 44 +3 3of3 BIS 102 Name K 9. Amino acid analysis is done on protein “Z”. The following results are obtained: m“ “f - “W °f Residues in Residues in Protein “Z” Protein “Z” - - [-- _ 11 + 1 - I- 10 + IO — 23 — 12 — _ — — — (20 pts.) a) Calculate the net charge, to the nearest 0.01, of protein “Z” at pH 7.6. Appropriate pKa’s are given on page 1 of this exam. You may use the back of this page, if you wish. Show all calculations. Put your final answer here: - ‘1 . 3| H scan M c; 538.». JAM N—Wm. a Q“ 2 9K“ + \03 ha Pu 2: pk“. +-\tn) ‘EL 91*: QK¢+l “h “Lb-s 6.9 +lu-3 "lab = 8,3 dab-hr.) h; '7‘ -_—_ 7‘Lt +k‘ 3935's: it wear: 1:; [£5 -.-. in.“ W a M ‘ l I . 0.199!“ 05.: 4— _._ 0.3874 :1: 4-3;? 20.02% b‘” I. my " 0"“ 2.5“: If?“ (’0.02HS)(tzj=¢o/f2qq> (—0.15L)(12\: ‘ +5” rS' ”'°' = if“) 4' ” "” '0 -'2 +Tr~l+a2q9 ~t.qq +0.3874, 3‘— ~q.3l +5 (3 pts.) b) At pH 7.6, would you use a cation exchanger or anion exchange resin to bind protein Z, in order to do ion exchange chromatography? whim alder“? ...
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This note was uploaded on 04/03/2012 for the course BIS 102 taught by Professor Hilt during the Spring '08 term at UC Davis.

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BIS 102 MT2 Fall 2010 - lof3 BIS 102 Name KgJ Fall 2010...

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