Need some help with this biochem hw packet pls! Given: vKm+Is) Km +IS] I. Which

Question

Need some help with this biochem hw packet pls! Given: vKm+Is) Km +IS] I. Which of the following is correct concerning the action of enzymes? a. An enzyme lowers the Energy of the products and thus makes the reaction more favorable. b. A I:l Enzyme-Substrate complex (ES) must be formed before the enzyme can convert the substrate to .) An enzyme speeds up a reaction by increasing the rate of the forward reaction and decreasing the rate d. All enzymes are so specific that each enzyme only acts upon one substrate. product. of the reverse reaction. A mutation that changes a Glycine to another residue in the active site of an enzyme has very little effect on the activity of the enzyme because Glycine is so small. Melatonin is a hormone that is produced in the pineal gland in animals and regulates sleep and wakefulness. The first step in the biosynthesis of Melatonin is catalyzed by the enzyme Tryptophan Hydroxylase. Consider the structure of L-Trp in the active site of this enzyme to answer the next three questions. Assume pH 7. 2. What type of residue might be located as a binding (recognition) residue at location 44? A polar noncharged residue that can form a Hydrogen bond. (salt bridge). interaction. a. b. A negatively charged residue that can form an ion-ion interaction c. A nonpolar residue that can be favorably involved in a hydrophobic d. 3. A positively charged residue that can form a salt bridge. e. Any type of residue since there is no significant feature on the substrate to bind to. what type of residue might be located as a binding (recognition) residue at location #3? a.) A polar noncharged residue that can form a Hydrogen bond. b. A negatively charged residue that can form an ion-ion interaction (salt bridge). c. A nonpolar residue that can be favorably involved in a hydrophobic interaction. d. A positively charged residue that can form a salt bridge. e. Any type of residue since there is no significant feature on the substrate to bind to. 3, which of the following might be a likely binding residue at location #2? a. Lys residue b. Ala residue c. Met residue 4, d. Asp residue e. Phe residue 5. Which of the following amino acid residue side chains would never be a catalytic residue in the active si of an enzyme? d. Glutamic acid e. Histidine a Serine Leucine c. Cysteine

Explanation / Answer

1. All enzyme are so specific that each enzyme acts upon one substrate.

2. A non polar residues that can form hydrophobic interaction.

3. A polar uncharged residue that can form a hydrogen bond.

4. Aspartate residue becouse it contain negative change.

5.Leucine is the amino acid never be catalitic residue of anu enzyme.

6. Km is equal to 1/2 Vmax.

7. Answer is B 3.2*103 mmole/min.

8. 1.68 mM/min

9. 3.50 mM

11. Alanine

12. Answer is option B ,This is an example of noncompetitive inhibition.

14. Km is the same in presence of inhibitor.

13. Answer is option B.

15. Pyridoxine is a coenzyme in biosynthesis of melatonin.

16. Answer B The active site of the pepsine probably have aspartic acid,and active form is protoneted.

17. Answer is option D

18. Answer is option A

19. Answer is option C

20. Answer is B Cellulose.

21. Answer is option C.

22. Glycogen is a branched homopolymer of D glucuse linked by -1,4-glycosidic bonds with -1,6 branched point.

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