Exam3key - Exam 3 C485 Fall 2011 Name This exam contains...

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Unformatted text preview: Exam 3 C485 Fall 2011 Name This exam contains 100 points plus 18 pts extra credit and will be scored out of 100 points. 1. (12pts) Draw structures for THREE of the following four molecules and give a 1—2 sentence, specific description oftheir roles in nitroggcessing (degradation, biosynthesis, or both.) Clearly mark the one you do not want graded. x ‘ _ , a _ _ r , it .9 Idiom/ms w awaits We“ firm: “ii MW , A. glutamate N 0 . ‘ I l U . . , I.“ ‘. 5 , a .7 i ;, m ‘l‘Z’BtI/i’tcrmr‘ and Siffre]‘lpclt if“. (I)?! Ll‘fl‘quf-‘(ci '1‘. .5 ,ilfllf ‘ Mimosa). be? mlflir‘éfll ‘l’oi‘MWl UM“ “jolt? 'le ’Ofi’mll @ “Haj-Wt removal er (Mamie 44m lac? :alwf‘f‘f‘. ‘qu mil-e? e366" km I n . "l'o her/(flier: offimiaams )t-xfi‘l Vl‘+("'[email protected]‘ B. glutamine _ . p - ,_ 'J, J _ .‘H‘ ‘ “1713 mm dWfl/lmqiu nfarzxfl hay-fifl‘ :43”).va ,f’f: e3...l(’{/1..nel aim/Wat mil—row re: J =””’-’”7‘ “Wiser we (We issuers-.4 Am) C. aEanine l“ gin hmp‘gnfl Ami/Via ia/l ‘h'jbvlflfis if ,3, haMfi-Wdfii‘lf lro nil/I47: / n r l " ' A e' - 9 ll 'l/lrm leieczl '10 ‘l’l’l"‘" live—f, WWW? if deml’” Wax ‘lO “l‘b : rm . , , '- rb/EAZ; (\l‘w’ ‘l/lfltl’l' 5x441. W13- W [Kai {/7c’z/‘f" (pl-lln’lm "A “Hill/ng (typify!) 1% D. carbamovl phosphate @ areal 53%? fire chik‘y’li' Mia-mamth m‘lfl Wéf'éi “Wk/“45 l"‘"'77 Q 4. 7 1 \_ 1. n . 4 fl i?’ll‘lUVl-z sl’l'l’O Cur 45-mion flleJfl/Ha‘l‘? 5’0 iul am l0“? “(J'IMJ l," - eel-rim. 2. {10pts} Which of the following amino acids are derived from a—ketogluta rate? ill“) glutamate .7: glutamine " “ K proline X arginine cysteine X ornithine aspartate serine 3. 20pts The degradation of aspartate can be achieved by PLP mediated transamination to produce a common metabolic intermediate. Draw an arrow mechanism with intermediates for the PLP catalyzed removal of nitrogen from aspartate. (You don‘t have to draw full arrow mechanisms for imine formation and hydrolysis. It is ok to draw an abbreviated form of PLP, but you need to draw the whole electron . sink.) Start with PLP covalently bound to the enzyme; stop at the structures of the deaminated product of aspartate and the nitrogen—containing cofa r. a: , ' ‘Lizr -‘ a I I i} C235 “’ )V r F ‘ {L/ " L V‘s/$14145 _- if?“ 'W‘fi “B will. \. flaw- m: i i liar if =Jas: 1 ' p. yaw; Win 1 X?" “N r V l \/ u _ il§_/w1_ \’ vbwz‘ For PLP to be regenerated, it has to release the nitrogen atom. To what molecule is the nitrogen tr sQRred, and what compound is produced in this reaction? " ‘0' ' ' | HIM??? Cdol\/\ l M.» l l. Aim} Pill? -. J i’ l 4. (12pts) Provide a biosynthetic pathway (no arrows needed) for the synthesis of serine from 3- phosphoglycerate. List any necessary cofactors and/or cosubstrates for each step. Is this molecule overall oxidized, reduced, or neither? Explain. OH 69 NH3 PO 0 __,_ 0 OH .u " N’ a $3 \JAM’O a. (A; *5 l’lérfilfi l 3/? \vi 5 5. (10pt's) Describe the roles of the three enzymes (enzyme groups) involved in ubiquitination of proteins OR describe the structure of the proteasome and how the structure is linked to its function. “l El -' am Mia; war w'l-ul TWA»?qu “l1; {+50 ugh-h m Hmrhjobvoijéisl-v mg) v-b-mr NH a3: ’MW 5 W 5 52 -. Unbitbwih'h shuffled; +0 5; (mm spews-c fives) l BE?- ivmsrus wbn‘gw'fiu‘v is - Pyoagsm £7“ “7‘ “9* WW Wham : 20$ cplz/Ljhc LM '5 a, H3 “flu/Mu? W g (’7 AW5LSG$ W M Ll passe/our mom; “5ch We 6. (12pts) Three coenzymes are involve in carrying activated one-carbon units. Match each of these units by writing the appropriate coenzyme next to it: THF, SAM, biotin, or more than one. Till: -CH3 “Till: {Hr -+l (incl/1 Ti‘ii: —CHO '2 iii: -CH=NH vi $0.» (.3th “T H l3 -CH= mic}, {02- Draw the structure of S-adenosylmethionine and explain why it has a high carbon transfer potential. n 0 “5t fan‘iwrly chafje; ' L/ /l\ r \h / 1 ii N A5 iii/lira“ mt’il‘é‘r‘fi jaw! 1 L19 [fiva {.10 C H - .3 7. (24pts) Answer two of the following questions. Clearly mark the ones you are answering. A. Although the degradation of the branched chain amino acids valine, leucine, and isoleucine are mechanistically similar, one is ketogenic, one is glucogenic, and one is both. Draw degradation pathways (intermediates) for the ketogenic and glucogenic degradations. Use the pathways to explain how mechanistically similar pathways can lead to different classifications. B. Draw histidine, and indicate in which metabolite each carbons ends up. Provide a degradation pathway that shows how these metabolites form. Include any necessary cofactors or cosubstrates. C. Draw the urea cycle with structures of all intermediates, including incorporation of ammonia into the cycle. Explain how this process typically clears ammonia from the body. Also explain how argininosuccinase deficiency can be treated by a low protein/high arginine diet. D. Threonine can be directly deaminated, leading to a citric acid cycle metabolite. Provide a pathway from threonine to this citric acid metabolite, including cofactors needed in each transformation. sudbmd Pm Mdfifmadfiié’) 8. (8 pts extra credit) The degradation of tyrosine results in the intermediate drawn below. A dioxygenase catalyzes the formation of a straight-chain intermediate through the cleaving of the indicated bond. This straight-chain intermediate can be hydrolyzed to common metabolic intermediates. Draw the structure of the straight chain intermediate and the hydrolysis products. Based on the hydrolysis products, is tyrosine ketogenic, glucogenic, or both? HO 9. (10pts extra credit) Thebiosynthesis of cysteine involves the PLP-catalyzed gamma- elimination of cystathionine (shown below.) A. Cystathionine can be made from the conjugationof what two sets of compounds? B. Draw an arrow mechanism for the gamma-elimination of cystathionine. C. What is the catabolic fate of the other compound formed from the gamma- elimination? G) NH3 9 e 002 020 s/fi/ —~—h- cysteine + 6') NH3 @ 66%.“: Awniyfi-iéflfl? cf g/l/[CVMO SQeMI’li-f’ @ m at ~ -- A: . M “r .—-— /\\J ‘A I‘ - q i”? Ora v .0” \RAS i" j 9‘0 Lit/39’? ‘ 33" W W365i \wa B J, 4 I Hi“ fl“? N143 (M M ._ /V “0}”wa r Cyéimw 0 C @ ~ ,t G) D ___________________ j y ,, m Co: 0,36 2% 2:; [OM/1% "’ i i SUCL‘Wji ...
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