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BIS102 Hilt F05 MT2 KEY

# BIS102 Hilt F05 MT2 KEY - lof4 BIS 102 Name Fall 2005 Last...

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Unformatted text preview: lof4 BIS 102 Name . Fall, 2005 Last Flrst K. Hilt Second Midterm Score (100): Equations: pH = pKa + log {[b]/[a]} (K3) (K1,) = 1 x 10’14 pH = - log [If] F = (q1 qz) / 8 1'2 Kb = x2/ (y-x) AG = AH - TAS Ka = 2/(y - x) pH = (pKal + pKa2)/2 —— __ _— _-x_ __ _-m_-x- —_ OliwotideN-tcrminal amino 9 .u. 2of4 4:— \p t m 1. Imagine that you have puriﬁed protein “Z”. Let’s assume that it‘é typical (i.e. average) protein. H 'H a-r but/HM (2 pts.) a) Protein Z’s molecular weight is probably about (a 0, 0170 5l"“"(?give units). 1 (2 pts.) b) Protein Z probably has subunits. This means that protein Z has ﬁoul-or ”59+ structure. (ﬁll in the blank with one word). I.“ (10 pts.) c) There are thousands of protein Z molecules in solution, in a test tube. The “solution” is made up mostly of buffer and some mercaptoethanol. Why is the buffer pH critical to the biological activity of protein Z? Be detailed and speciﬁc in your answer (i.e. do not just say that the pH has to be correct for protein Z to have activity; instead explain why the pH has to be controlled in terms of protein structure). Then explain why the addition of mercaptoethanol was important to the proper functioning of protein Z. Wh the correct buffer H? ~ ‘ y 1M: M3 Wang; emu ma +0 k» ma-mmeot. *0 BOA—(4 aye, itmﬂdfm “m, QV‘O\*<:W\ 30“”). Lia‘ffyf'rucj'U-rﬂ. (‘4'me are, a&&J\HWJ.,QLaj .UM-SWM in 2° Wu&wr€_\. To taco? ”5w\#fA-L bun ~ , , ‘ ‘ H Ear m —5 S *"\ 3.0 not MM AMSuW-wﬁz, Jaw-514, injwnd' rt, cm 69/ n0(mo—Q 3° aha/w Li" 5+Vuu~+wrt (10 PtS.) d) An internal piece of protein Z was separated and is shown below: M :0, H i‘ “6" H M aw» ~> *rﬁ9‘r A 01 at o g 01 H a! H! o a: s n \ ‘\ ‘ gt ‘ 1—. ‘””"Cc“c“"’r"‘z”‘-*':’”%““WE“WW‘VWD H £3: CHI H L“; H {c R I?) V“ («q Riﬂe H ' —— 1 -- ~ .. «m \ L \ a. '2: ., Q a. .1... .2» m («hm R t" (CK an; x ‘0- L: ““2 ENE/L +2. +3093 ‘ (c, N“; “‘- «C.— \"(’H H Careﬁilly mark with labeled arrows where the various protein sequencing cutting tools would cut (e.g. an arrow drawn to the bond that is cut by chymotrypsin, etc.). If a cutting tool makes more than one cut, then show all of the places where the cuts are made. (8 pts.) e) Referring to the internal piece of protein Z shown in part “(1” above, draw a rectangle about the region in the above peptide that is most likely to be involved in protein misfolding. Then explain why this is likely and how a cell can ﬁx the problem. "V' . +3 . . “”223 Pro\in€$can» ha gowMD. ‘m. Hun, <L\5 Wﬂjuvwhm ‘ wax-W “mm, m “(odd m ewe-iaurai'l‘m. An emu/rm) proﬁne. vmemm' cam ‘eiﬁ “It—V». 4'2, 3of4 BIS 102 Name Kg? 2. The results of a limited carboxypeptidase A and B reaction on an unknown peptide gave the following results when the released amino acids were spotted on a TLC plate: 0 S t L 1 0“ *’ solvent 0 L‘ if?“ sample origin The student used a polyamide TLC plate. Polyamide is a nonpolar material (polyamide is a nylon type material). (5 pts. ) a) What type of solvent would you use? Explain why you are using thistyp e of solvent. Qohw 250mm C cwwpawul +0 Web-1Q) wa M +L¢ A W “ WMM ﬁsVd1mnj 90‘ ‘Hrw 630.11.. *0 "make. a. (June. bet-W M «M 9 0-4-44 (6 pts. ) b) Appropriate standards were run and the spots were determined to be L, S, and A Label each spot on the above diagram with the appropriate designation, i e. “L”, “S”, or “A”. (6 pts. ) c) What do you conclude about the sequence of the unknown peptide? Explain how you carne+ to this conclusion. M C Rrwna’Q. SW 15 grch-Jollj W... 5 - A _. L H M 5‘51" WiHm H—n. Srquﬁd' mound— rt M6734 1‘“ 4490-4 C442— 1..“ ’ 3 yaw ram g'ud’r 0»qu hence, is ng Inc M [MW :1me 3. (26 pts. ) Please ﬁll out the following table, concerning allosteric effectors of Hb: H +1 ex ead’es /$4701“ Central cavity of tetramer 4of4 BIS 102 Name % 4. A histidine residue in a protein has a side chain pKa of 6.3. Due to a conformational shift, an amino acid residue moves into close proximity of this histidine, shifting the histidine pKa to 5.7. (10 pts.) a) If the protein that has the above histidine residue in it was in a solution of pH 6.5, what is the change in the net charge of this histidine side chain, due to the conformational change? Show all calculations. -\-\ as: 6'3;‘%%\ 65= 57+l'j/km- o z =lu1’19; 0.?5 [W21 l-SS’ ~ 3; 4.30 c *2: \ t J'— : *3 a.= 5936’" 0.397 *3 ,. a»: 790 0"?" warm—W =- a (5 pts.) b) What is the likely identity of the residue that caused the pKa shift for the above histidine residue? If there is more than one possible candidate, then give them all. Explain why these candidates caused the shift in the histidine pKa. a“. lid/I"- U") a, o; 4 we M‘m v: + \ 4.0.; ’Efm m “" “(3" “34‘? UK) +0.; fnzlweﬂ \‘l’ +0 \M N—Wmiﬂe‘o- ”H34. ”9‘5 a» pro-FM . 5. (10 pts.) What is this all about? Give a detailed explanation of what is happening in each picture. mod ? emu“ #owwa,“ L4)? 69*“ " 6“"3’3 ”6‘?“ for egg) shims? :4:— am weumdim no»ch CH) (’ﬂw“ 4° Q “a “v.3. gelding _ eak- win ‘V\ {5793? (Mal-We: Luuﬁvw gum“: Ml” MW‘B .. ...
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