Faculty of Science, IUG

`Faculty of Science, IUG

Dept. of Chemistry and Biochemistry

Mid-Term Exam.

Enzymes kinetics(Bioc4307)

Date: 30/11/2005Name:------, NO.------

Answer the following:

I- Starting from M.M. equation, prove that Ln[S]0/ [S] = /K t and about the first order kinetics, show plots of V, [S] and [P] vs. t. (10pts).

2-Close proximity of one enzyme to another in the Pyruvate dehydrogenase complex increases the overall rxn rate and minimizes the side rxns. Explain the mechanism of rxn catalyzed by the complex showing the role of each enzyme component and the role of the 5 different coenzymes involved (10pts).

3-Write the mechanism of action of the following serine enzymes: chymotyrpsin, tyrpsin and Elastase. Why specificity of these enzymes are different? (10pts).

Faculty of Science, IUG

Dept. of Chemistry and Biochemistry

Midterm Exam.

Chemistry of proteins and lipids(Bioc4308)

Date:10/12 /2005Name------& NO.------

Answer the following:

I) Compare between Cahill Cycle and Cori cycle (with respect of the mechanism and the condition of occurrence)(6 pts)

II)Adipose tissues utilize excess glucose for TAG biosynthesis. In other words, excess glucose intake causes obesity. Discuss by using suitable scheme.(10 pts).

III) Explain by structure gamma-glutamyl cycle (Alton Miester Cycle)? How many ATPs is required for each cycle? What is its purpose? (8 pts)

IV) Explain by structure trans-deamination reactions and why these vital reactions should continuously occur? (6 pts)

Faculty of Science, IUG

Dept. of Chemistry and Biochemistry

final Exam.

Chemistry of proteins and lipids(Bioc4308)

Date:January/2005Name------& NO.------

Answer the following:

I) Account (write reasons)(6pts)

1- Fatty acids are not Glucose source during starvation

2- Glutamate plays a central role in disposal of ammonia.

3- Although human cells have same chromatins number, there are ~200 different cell types.

II) Compare between

1-Cori cycle and Cahill Cycle (with respect of the mechanism and the condition of occurrence)(6 pts)

2-Malate–Aspartate shuttle and Glycerol shuttle and (6pts).

III)Prepare (24pts)

1-PRPP from ribose-5-Pi(2pts)

2-AMP from IMP (Show structure)(3pts)

3-AMP from A and PRPP(2pts)

4-CTP from UTP(2pts)

5-d-CDP from CDP(2pts)

6-d-TMP from d-UMP (Explain how can N,N-methylene THFA regenerated)(3pts)

7- Ser. from 3-PG(Show structure)(3pts)

8-Cys from MET (4pts)

9-Gln from Glu and V.v. (explain the importance of both reactions)(3pts)

IV) Compare between DNA replication and Transcription with respect of the following(8pts)

Bonus question: The following segment of RNA sequence is transcribed from the middle of the gene, but the correct reading frame by ribosomes is not known. What amino acid sequences would be encoded from each of the three possible reading frame? Comment which is the most likely of the three (5 pts).

5’–ACGGCUGAAAACUUCGCACCAAGUCGAUAG-3’

Faculty of Science, IUG

Dept. of Chemistry and Biochemistry

Final Exam.

Enzymes kinetics(Bioc4307)

Date: Name: NO:

Answer the following

I-Complete the following (8pts)

1-Kp= ------

2- Kp/Km (called -----) ≤ ------.

3-pyrovate dehydrogenase can be assayed at ----nm.

4-Vo/Vmax=------= ------.

5-E.U. = ----katal.6- ----in vivo ≤ Km.

II- At steady state of a M. M. enzyme prove that Vmax t = [P] and show plots of V, [S] and [P] vs. t. (13pts).

III-(a) What concentration of competitive inhibitor is required to yield 75% inhibition at a substrate concentration of 1.5x10-3 M if Km = 2.9x10-4 M and Ki = 2x10-5 M?(5 pts)

(b) To what concentration must the substrate be increased to reestablish the velocity at the original uninhibited value?(5 pts)

III- Assume that Chemotyrpsin can be inhibited un-competitively in acidic conditions.

a)Derive the rate equation(6pts).

b)Show by plotting, how you can determine Ka.(4pts)

c)Show the suitable plot that distinguish between NCI and irreversible inhibition(4pts).

IV- If an enzyme preparation (1mg/ml,360,000 Da) has a reaction rate 120 µM/min.

a)Calculate kp,1/Kp and explain your answers(9pts).

V)Given the following enzyme purification scheme. Determine % yield and purification factor(10pts).