HQ-CC-Scanner20091204131501

HQ-CC-Scanner20091204131501 - 3(‘ (CC). OSes-f V. (12) A...

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Unformatted text preview: 3(‘ (CC). OSes-f V. (12) A biochemistry graduate student isolated a peptide hormone from Gila monsters. He found its amino acid composition to be Ala, Aspz, Glng, Ile, Lys, Met3, Phez, Trp. Treatment with carboxy- peptidase A yielded Asp. By cleaving a sample of the peptide with chymotrypsin and performing the Edman degradation procedure on the resulting fragments, he produced the following peptides: Phe, Asp-Met-Gln-Phe, Lys-Gln-Met-Asp, Ile-Ala—Met-Trp, Treating another sample with CNBr, the student produced the following peptides: Asp, Asp-HSL (homoserine lactone), GIn-Phe-Ile-Ala—HSL, n] Trp-Phe-Lys-Gln-I—ISL. What is the sequence of the peptide hormone? In your answer briefly describe It the purpose of each step. , r’j._ -- ' K — I, u - \fi'l— f-Nntd ' iCV Btu. L , _rb\4vf~~1 vervhgl‘ EC (JOHJC' Asp“! P‘hfl M M. f ’1' / ’/ (Lb-1M0 WWW“ L‘Mfir Pike A30 ASYJ - Mel — (rln— ‘P‘n‘i A3? -HSL- trim" “Plumb—l LVI5— Giname Ola-l) Ila“ A\°\ “ Mel _T(Y’ 1"" _fki _L\15_ n (“Ch-J VIA/k we, AW- me+ —t,\n’ —W — (J-ln __ el‘ ASf’ ‘/ met» _. ex thw‘vw'fi“ b cm“ I .'7 ' A Mi. ' ~ ‘j- H’“ N_ Thur,“ We Lr.r\our‘1{’€r’ Hdwc‘ A \5 \J’J“K ‘0 [fl ‘ I WI umcd ’ I3?" dirt.) - 2 L1 wcl Tr:—-\"\"‘7 m Wax-m with tkwmvbw ‘ U‘” '“ J ‘” .‘HN X‘ w'nhn user} Lu‘)" \V‘c" \l and HM ‘Fmfll sul‘fi“ 66‘ I “ABA L; m r“ t . L (indium! 1w W; l0: )Urc “‘0 (karma brat it} {or « iljl (( A um! Anatvtv. 7 s a. tlice} \‘lI'VS‘ :5 Low 1 cvviVCx/l c l m7 kl «Eel-J‘xw. "L ffijf’ ' 77.“? EF’EO’A' ' K /\ THTC'CA {26'5" IV. (14) Short answer. Answer any two of the following three questions in several sentences. at. b. C. The mass of a newly purified protein was determined to be 60 kD by gel filtration chromatography. Chromatography in the presence of 6 M urea yields a 30 kD species. When the chromatography was performed in the presence of 6 M urea and 10 mM 2—mercaptoethanol, a single molecular species of 15 kD results. Describe the structure of the new protein. ./ /, / You are performing site-directed mutagenesis to test predictions about which residues are essential for a protein’s function. Which of each pair of amino acid substitutions listed below would you expect to disrupt protein structure the most? Explain your reasoning in several sentences for each case. (a) Gln replaced by Asn or Asp. (b) Val replaced by Ala or Phe pvt-M In Qua“ .2 C, lUiI-MIAG LIL-re repihttd H\ Asptxmj 1"? W Far-LE uh LUV“) “0" film—Ne Hui th“ HUH‘VCV IS" L, hmmv ' laced L, Ha ASP" R" J “W? IS rep . AL“) hQi' Gkarbé LL WC Fruit-"9% C‘hfilyl’r whiLi-fl would fidt)r'url# “Phe {){Ui‘ki'f‘s 5 ivu'Li'uV'E W“; six In CV30” Vah‘ne wbt'e. ('E (I \LLG pk L4 - H“ A i 6' nW‘Q 9W" HAG" (— Smurf R new") wuuid kmlflp(“- I": Hus-.4910? Van": U “P laced U‘ {'1‘ [mafia “I‘m'he ‘i‘JJ 3" 5W+ ‘ rvwdn )v t lmhr Elm—'7' [tr-J"? '1’ moor-6‘ 5‘14” ‘Lwi'WflVmu in“; Under the right conditions of pH poly-L-glutamate, a polypeptide consisting of only L-glutamate 4 (“mi residues, will form an a-helix. Altering the pH causes the loss of helical structure to form what is am“ called a random coil. Predict the pH dependence of the helix-coil transition for poly-L-glutamatc. Explain your reasoning in several sentences. quuvt m “VWHW Wort. Dnde @\ Univ] 09 (r lui-umtie wesl'dufi SlAUr 9 \Ui—mek”? (J in? [fizfl‘gfibwakd {he ’6 H br- LU “(’5 i1) fin.le Urun Erecktnj dawn We (Flt/Mi?) would lead In) W? flm‘JUW‘ '40“ to r. to; pl lo a W 7 is» (Wm: 3c, (Col «05¢ l" III. (12) Describe how you would prepare 500 mL of a 250 mM glycine buffer at pH 9.0. Sodium glycinate (The sodium salt of glycine Na+ 'OOC-CHg—NHg+ , Formula Weight = 97.05 g/mol), 1.0 M HCI, and 1.0 M NaOH are available. Please show your work. A V 3: 800 ml- mull L/ N\: 150mm L \ 150w) 5M : W SOD-“L w\ Y0 1 f O l 0 300 ML 611.03 \j : \2 \3 3”“ 0‘ 5mm“ WW“ W 3090\98 - . L \d (“Null “N has way MDWM ' mew W“ @‘74 den\ gl- Wl 95 ncutké’cl Tlnm Null l‘ l'LllflJ lhtl \01 w Fo(m‘_,\¢. UE‘Dln\' 1 LOU‘J ‘n Mgr vauunl In 3w..wa needed *v (mu m “mun MW ml 1 mm com and of \puse as new wxlw'l L 550* m‘m PM Llka E,“ fuwvc 0" 3.0 ’— fl£c(/ r 7 ‘ 972147 442%.“? rd ['40 07Z EZV'A/L .E’wx/g’” k. ) ‘ .gff/Ld/ »%’(o/zz.uré/ (“3%- €th/ ,CT/{r/l‘ "Cd % Lafifé l C Q/é'r"'r% 7g, fl \ Zc/ N?!“ Na p Use the data in the table below to answer question 14 and 15. 1 Protein Molecular mass (kD) pl Lysozyme (hen) 14.3 11.0 ‘ Insulin (bovine) 5.7 5.4 S Myoglobin (horse heart) 16.9 7.0 3 Ribonuclease A (bovine) 13.7 9.45 2- GAPDH (subunit, rabbit) 36 6.55 '1 14. Which protein would elute first in a gel filtration experiment? ‘\ a. l GAPDH Myoglobin c. Insulin d. Ribonuclease A e. Lysozyrne 15. What would be the order of proteins, from cathode to anode, in an isoelectric focusing gel? a. GAPDH, Lysozyme, Myoglobin, Ribonuclease A, Insulin b. GAPDH, Myoglobin, Lysozyme, Ribonuclease A, Insulin c. Insulin, Ribonuclease A, Myoglobin, Lysozyme, GAPDH d. Insulin, GAPDH, Myoglobin, Ribonuclease A, Lysozyme @ Lysozyme, Ribonuclease A, Myoglobin, GAPDH, Insulin 16. Protomers of oligomeric proteins are related by rotational symmetry. T . What symmetry is illustrated in the figure to the right? : D4 , ‘ . C2 , ' , ' . ' '- bgqti r <4) none of the above. V II. (14) Draw the structure of the predominate ionic form of the tetrapeptide Arg-Cys—Asp-His as it would appear at pH 9.0. 0‘ 1" H 1" H Hi fill U/igfiF‘-NA—d~uue d—N’F“C”@i£m I H awe. ? \ l l / 0* r\ (H - , (“L (‘01,, c1 2. L “6* CW6, uwul 1 r", —' . - (“A ’ ’C\\ “~31? bk ‘1 1 (H1. l @L 7 , 2/ E” / } H+ Nr/i my TQVQC‘ flow.“ 6. Three buffers are made by combining a l M solution of acetic acid with a l M solution of sodium acetate in the ratios shown in the table. Which statement below is true? 1 M acetic acid 1 M Na+ acetate Buffer 1 10 mL 90 mL W” ‘3‘“ Buffer 2 50 mL 50 mL Buffer 3 90 mL 10 mL 3.. 6% 0mm . pH of Buffer 1 = pH of Buffer 2 > pH Buffer 3 . pH of Buffer l < pH of Buffer 2 < pH Buffer 3 . pH of Buffer 2 > pH of Buffer l > pH Buffer 3 @ pH of Buffer l > pH of Buffer 2 > pH Buffer 3 b c d e. none of the above 7. Which amino acid is not a polar, uncharged amino acid? a. Tip b. Tyr c. His d. Cys both a and c 8. In what order will the following amino acids be eluted from a DEAE-cellulose column by a buffer at pH 6: Arg, Asp, His, Leu? “,3 n : {0.1 5' a. 1.Arg, 2. Asp, 3. His, 4. Leu A 1 : 1.51.; b. 1. Asp, 2. Leu, 3. His, 4. Arg 5" " G) LHis, 2. Arg,3.Asp,4. Leu Hm pl 1 T“ l. Asp, 2. Arg, 3. His, 4. Leu L2,, (,1: (0.0% Arg, 2. His, 3. Leu, 4. Asp 9. Which reagent would you use to alkylate thiols after reduction by 2-mercaptoethanol? a. HI b. acetic acid © iodoacetate d. acetamide c. both c and d 10. Which amino acid would most likely be found on the surface of a globular protein? a. Met b. Tyr fl Ser @ Lys e. Val Questions 11 -— 13 are based on the 18 residue peptide whose one-letter sequence is given below l 4" O " 4- «-4-- Wflfiromfimr PSDK 11. What is the net charge of the peptide at pliysrological pH (pH 7&? 3 a. -l b. 0 2 e. 4 12. How many fragments are produced after treatment with trypsin? a. 5 © 4 c. 3 d. 2 e. 1 13. If this peptide forms an ot-helix then the carbonyl carbon of alanine hydrogen bonds to the backbone N—H of histidine b. glycine c. prolinc d. lysine e. none of the above -. n v. Tm: ‘12»;ka Chemistry 3785 First Hour Exam Name I t 1 4 Summer 2009 100 points Mon. June 1, 2009 Points Score Points Score I 48 , IV 14 u 14 ‘ V n 111 12 1 Total 100 A table of pKa values is found on page 7. l. (48) Multiple Choice. Circle the letter corresponding to the best choice. Three points each. The titration curve for the glycolytic intermediate 3-phosphoglycerate is shown below with numbered points. The pKa values for the ionizable phosphate hydrogens are 1.2 and 6.8. and the pl'x’a for the carboxyl group is near 4.0. Answer questions 1. 2. and 3 based on this information. iI: coon ‘ ' H—e—on (H) throne—0H 01-1 3-Phosphoglycerate t I i ‘ 3 Equavalcnts Na()H 1. At what point is the major species the dianionic form '? a. 2 3 1 c. 4 d. 5 e. 6 2. At what point is [R—COOH] = [R—COO']? @ 3 b. 4 c. 5 d. 6 e. 7 a Atwhmpomtmabmn9h%cd3PGindw‘OOCJLOPOf'mnn? a. 3 b. 4 c. 5 6 e. 7' 4. Based on Coulomb’s Law what factor or factors would decrease the attractive force between charged particles? a. an increase in the charge ofthe particles. cg. the ions of MgSO4 should have a stronger attractive interaction. all things being equal. than the ions ofNaCl. b. decrease the distance between charged particles. ' "1. 1.; c. decrease the dielectric constant ofthe medium. i 3 "’6’ d.bmhbmmc. ‘ ' @ none of the above. 5. What percentage ofthe thiols of cysteine are deproronatcd at physiological pH (le 7.4)? a. 90.996 (:9 9.195 c. 9994 d. 194 e. 095 art 1 7%: H ‘“1g—T' m493a0~flstoih1ma ...
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This note was uploaded on 11/24/2011 for the course BIO 400 taught by Professor Raganbower during the Winter '10 term at Drexel.

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HQ-CC-Scanner20091204131501 - 3(‘ (CC). OSes-f V. (12) A...

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