E3_+_A_scanned_copy

E3_+_A_scanned_copy - Tn addition to arninotmnsferase....

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( 10) 1. Tn addition to arninotmnsferase. another enzyme in the arnino acid metabolism which ;11so uses pyridoxn! phosphate as a cofactor is the threonine aldolase converts tlireonine to gIycine arid acetaldehyde. The I-eaction is shown here. Q Helow he relevant szructrtre of pyridoxnl phosphate. Propose a reasonable mechanism for the tlireoriine aldolase reaction. You will need to draw the chemical structures of the intermediates. and arratige them in tfle order proposed reactior~ steps. Use the structures provided here to work out the proposed strtlctures reaction intermediates. Remember to indicate the orientation of R key bond in the threonine moiety to the plnne of x-electrons in pyridoxal ring. 0- I+ ~'fj /F/I 'c cob- Y/ \- C - =LV - &&rc b l
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Name * P- 2 Give short answers to the rollowing questions: (2) 2. Name the enqme for the key regulatory step in cholesterol biosynthesis, to wllich several ~harmacologically important compounds (statin drugs) are targeting. (2) 5. How many carbons are there in cholcstcrol? 4. Cholesterol is made by assembling chemical moieties with 5 carbons. Give the number of carbons (multiples of 5's) in the following intermediates in the pathway of cholesterol biosynthesis (1) Farnesyl pytophosphate 15 (I) Dirnctl~plallyl pysophosphate 5 (1) Geranyl pyrophosphate (1) lsopentenyl pyrophosphate 5 30 (I) Squalene
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Cq) 5. DNA damage can occur without insults from outside of cells. Cytosine can undergo spon tnneaus rleamination. Write down the chemical structure of cytosirle (base only. no deoxyribose moiety). and that of the dearninated cytosine. Name tllc procluct of cytosine deanlinatiorl reaction. Briefly explain why this will lead to damage. to) 6. Same repair pathway by which above-mentioned damage can be repaired. 'I lie following diagram is used to denote the DNA damage site (base at the bulge). Use this as a starting point, illustrate the steps involved in the repair pathway.
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This note was uploaded on 10/27/2008 for the course BIO 118 taught by Professor Greenleaf during the Spring '08 term at Alabama.

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E3_+_A_scanned_copy - Tn addition to arninotmnsferase....

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