上海交大Biochemistry Test(2010年二年级英文考试卷答案)

Biochemistry Test （Chapters 7 ~ 10）

II Multiple Choice (20 x 2.5 = 50)

1.

Inside red c e ll

s, increasing concentration of will not lower hemoglobin's oxygen affinity. (A) CO 2 (B) H + (C) 2,3 –bisphosphoglycerate (D) O H － 2. When free hemes are exposed to oxygen, will be formed.

(A) aggregation of hems (B) superoxide

(C) an oxo heme an oxo-bridged dimeric heme

3. Biotin is required for catalyzed reactions.

(A) protease (B) restriction enzymes

pyruvate carboxylase (D) protein kinase

4. When mitochondrial aldehyde dehydrogenase is deleted, the person is very sensitive to alcohol. The reason is .

(A) the person is devoid of aldehyde dehydrogenase completely.

(B) the person is unable to convert aldehyde to acetic acid.

(D) the person is unable to convert aldehyde to acetic acid at high concentration of alcohol.

5. Group specific reagents for serine are described in the textbook.

(B) lodoacetamide

(C) p-hydroxymercuribenzoate (D) 2,4-dinitrophenol

6. It is believed that the reason for sickle-cell anemiais caused by E6V mutation of hemoglobin β is .

(A) The mutant protein is not as stable as wild type.

(C) Oxygenated hemoglobin S can not release the bound oxygen.

(D) The balance of α subunits and β subunits are destroyed.

7. When phenylalanine residue of Tosyl-L -phenylalanine chloromethyl ketone (TPCK) is substituted with lysine residue, the

regent will block the activity of .

(A) chymotrypsin (C) elastase (D) pepsin

8.

N ,N -Diet hylproparg y lamine is a for m o noam i ne o xi d a s e. (A) transition-state analogs (B) group -specific reagent (C) affinity label 9. β-thalassemia is caused by of β-hemoglobin chain.

(B) the mutation.

(C) excess (D) none of above

10. Based on the structure-function relationships, D189K mutant of trypsin is likely to cleave the peptide bond after .

(A) Lys (B) Phe Glu (D) Gly

11. The distal histidine in the oxygen binding pocket offers to the bound oxygen molecule so that the superoxide

less likely to be released from myoglobin .

a hydrogen bond (B) a proton (3) a negative charge (4) a steric hindrance

12. The substrates for all NTP-dependent enzymes are .

(A) NTPs

(C) both a and b (D) only ATPs

13.One molecule of deoxyhemoglobin has site(s) for 2,3-BPG binding.

(A) 0 1 (C) 2(D) 3

14. A catalytically competent active site can be generated for only on substrate binding.

(B) all enzymes

(C) trypsin (D) non of enzymes

15.Effect of on ATCase catalyzed reaction makes the sigmoidal behavior of the kinetic profile less-pronounced.

(B) CTP (C) cAMP (D) non

16.In eukaryotic chromosome, histones are associated with genes that are being actively transcribed.

(A) without acetylation (B) with less acetylation

(C) with acetylation

17.Threonine residue in a target protein can be phosphorylated with kinase.

(B) threonine (C) tyrosine (D) polynucleotide

18.When procaspases are activated by various signals, the cell death is .

(A) avoided (C) completed (D) stopped

19.The accumulation and precipitation of free α-hemoglobin is prevented by .

(A) heat shock proteins (B) inhibitors of α-hemoglobin

AHSP (D) unidentified factors

20.The structural change of trypsin-inhibitor, or trypsin itself, take place when the enzyme and inhibitor form the

complex.

(A)does does not (C) must (D) may

III Fill in the Blanks (10 x 2.5 = 25)

1.In order to overcome the limit of diffusion and proton transfer in the hydration the hydration of CO2, carbonic anhydrase uses

Proton shuttle with His 64 mechanism to transfer proton

2.Antibodies that recognize transition state analogs should function as catalysts.

3.The oxyanion hole of subtilisin is constructed by amino groups from both in the backbone and in the side chain of an

amino acid described in the textbook.

4.In order to address stereochemistry of EcoRV catalyzed reaction, the researcher performed the reaction with the DNAs

labeled with phosphorothioate at cleavable site as substrates in water labled with 18O.

5.The enzymatic specificity of EcoRV is determined by the specificity of enzyme action rather than the specificity of

substrate binding.

6.P-loop has an amino acid sequence of the form Gly-X-X-X-X-Gly-Lys that is located between the first β- strand and the

first α- helix and interacts with phosphoryl groups on the bound nucleotide

7.PALA is tha analog of two substrates that is used for locating ATCase reactive site.

8.The increase in serum levels of H4 LDH relative to H3M one is an indication that a myocardial fraction, or heart attck,

has damaged muscle cells, leading to the appearance of some isozymes in the blood .

9.The regulator subunite of Protein kionase A contains the sequence Arg-Arg-Gly -Ala -I1e that serve a

pseudo-substrate to prevent the entry of protein substrates.

10.Pyrrole 2-carboxylate is a potent inhibitor of proline racemase.

IV Short Answer Questions (3 x 5 = 15)

1.According the supervisor’s direction, Miss Wang using glutaraldehyde to immobilize a novel enzyme ( the active form is

monomer) on glass beads coated with amino groups. Although all possible inactivation was prevented from, her immobilized enzyme was actually inactive. Propose what inactivate her enzyme and design a method to improve the immobilization. Answer: The active site of the enzyme may be big enough to permit glutaraldehye enter and modify an essential positive charged amino acid of the active site to block the enzymatic https://www.360docs.net/doc/111338521.html,ing

cross-linker with larger molecular backbone would be a better choice.

2.Mr Li has purified a nucleotide kinase and measured the kinetic parameters with different substrates (listed in table 1). Please

list your conclusion and state related reasons.

Answer: The optimal substrate should be GDP as the Vmax / Km is maximal. In another word, the enzyme is specific for GDP.

3.If your boss like to screen an inhibitor against a viral protease from extracts of Chinese herbs, could you propose a practical

research schedule.

Answer: (1) The enzymatic reactions are performed with N-acetyl-amino acid p-nitrophenyl ester carrying different amino acid residue in order to determine the optimal substrate for next screening.

(2) Screening reactions are performed with the optimal substrate in presence of the extracts you have made.

Extracts behave the most negative effects on the enzymatic reactions are potential drugs.