CH339L.09.Test3.Key - /;' CH339L Test 3.09 Name Hi (1; 25...

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Unformatted text preview: /;' CH339L Test 3.09 Name Hi (1; 25 points) Presumably it did not escape your attention that we skipped over both histidine biosynthesis and degradation. If you were smart, you went ahead and figured out these pathways. If not, you get a chance to do some of that again, here. ‘CIOO COO f I N5-FormiminoH +':,-| 3 NH: H20 H20 “4 oate H4folate 3N—C—H 'l EH2 ##4## c:nz c .. G) Y ® @ x Q) .._..CH2. / HC/ \TNH l Formimino (a; 10 points) Based on your knowledge of folate chemistry, draw the intermediate ngiggundx. Hints: the atoms that will comprise the formimino group are circled on histidine. and while the red carbons (see Figure 18-26) are the same between the two compounds, the representation is inverted (top goes to bottom, bottom goes to top). I I __ i L_ .. t..- L_\ . _ I , - : { ill—r (b; 15 points) Assuming that the deamination in reaction 1 is mechanistically similar to a dehydration, draw the mechanism (push arrows) and draw the resulting compound Y. (2; 20 points) Below you will find cystathionine conjugated to a schematic of PLP. Carry out the reaction catalyzed by cystathione beta lyase, which will result in the production of homocysteine, pyruvate, and ammonia. There are at least two intermediates that you need to draw. At the end, show the compound, Z, that leads to the non-enzymatic deamination to produce pyruvate and ammonia. h r {I boo— s—Hzc—F—w/ NH3+ ‘CXDC +H3N intermediate 1 1 Intermediate 2 + Homocysteine H20 PL? + Z -' \ Pyruvate + ammonia (3; 40 points) The pathway shown below represents the biosynthesis of lysine in archaebacteria. It is one of the few amino acid biosynthetic pathways that substantially differs between organisms. The first three reactions mimic reactions from the TCA cycle, but no other cofactors or products are shown. On the following page draw Q, R, A, B, C, D, and E. Note that acetyl-CoA is added to B and acetate is later removed from E. Alpha-ketoglutarate + acetyl—CoA - r: ' -- v.2";- ' i i. -- _'—x.«fl ~.l S! [X r l A — .-_' Q J/ l l l l_!Lt-:\’/ \._\/. + 9,/ i ll 3 I r' If r/ f 1 ——— ‘— rim “’1 R R (0555’ { Hm“. [J Glu aKG O 6 x E {A NH: HOOC A l--l:'.3'I’_'-{', '_ - i,_,.L\ __ Ketoadipate Acetyl-COA I COASH ._:HJ 1. Pi L H ._ . . i H/ I . i" u . "- _ I J I D C ‘_____ B art”? __ '- ‘. 4-: 6: fl 4/ fl ' " " Glu NAD+ NADH + ADP ATP > H+ aKG NH2 r." / ANNE—w?- E 6 N m H2N COOH _ , l l‘J/V\' “Lair-H H90 Acetate Lysme .. (4; 10 points) Reactions B -) D in Queslton #3 are similar to what transformation(s) during amino acid biosynthesls in Chapter 22? Below, you need to name a compound analogous to B, and a compound analogous to D. N" {Ml-+5 gfléfl'nu pic? / : u “a ;.:I‘.-_- I I I .. '7 “a 5‘ (5; 10 points) The compound shown below is a stable, allosteric *activator* of an enzyme. Deficiencies in this enzyme lead to hyperammonemia in humans. Name the enzyme. H O H YNN‘H. O I O OH In contrast, in bacteria this same compound leads to inhibition of growth, by inhibiting a key enzyme in amino acid biosynthesis. Name the enzyme. 2‘ Lil {w "i’ y; a: a :‘tfeit fag/r? f I r; I; i" r '\ ' '3 If .\ - I (6; 15 points) As a doctor, you have a newborn exhibit the symptomology shown below. You quickly discern that they are suffering from a genetic disorder similar to methylmalonic acidemia (MMA), one of a number of organic acidemias. However, initial tests do not show excretion of methylmalonic acid, but of another compound. You realize that the deficiency is in [E/nzymername: r? (i/I'r‘é'mg')a:u:' and Immediately order a diet restricted inf__odd chain'fatt acids and four amino acids. Name two of the four amino acids: " \ _i .' . .-, -' Onset Presentation Outcome Neonates Similar to MMA neonates May die even with aggressive treatment or if prompt treatment is not instituted Some exhibit hepatomegaly or develop seizures. Acute encephalopathy. episodic ketoacidosis, or developmental retardation without metabolic decompensation may be seen Less severe form with episodes of vomiting. lethargy. failure to thrive. protein intolerance, seizures. or psychomotor abnormalities (e.g.. floppiness and hypotonia) Late onset — older children (>3 months) and adults ...
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This note was uploaded on 10/21/2009 for the course CH biochemist taught by Professor Kaplan during the Spring '09 term at University of Texas at Austin.

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CH339L.09.Test3.Key - /;' CH339L Test 3.09 Name Hi (1; 25...

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