Chemistry 340 Quiz 6
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Answer with only one choice even if more than one is correct. Use a choice only once.

1-4 are about chymotrypsin. 1-2 are about the reaction; 3-4 are about the active site and mechanism.

1-2. Use these choices: (A) substrate 1; (B) substrate 2; (P) product 1; (R) product 2.

     B         H2O

     A     the peptide bond next to an aromatic
             ring

     P      the protein with a new N-terminus

     R         the protein with a new C-terminus

3-4. Use these choices: (D) aspartate; (H) histidine; (O) oxyanion hole; (S) serine;

     O       stabilizes an O intermediate

     S       forms a covalent bond to the substrate

     H         accepts H+ from serine

     D         stabilizes His+ with an ionic
              interaction

     H         donates H+ to the substrate

     O         consists of two α–NH groups in the
             chymotrypsin backbone

     H         accepts H+ from H2O

     O         in the active site but not the catalytic
           triad

5-8. Use these enzymes:
(Y) chymotrypsin; (X) hexokinase; (E) enolase; (N) carbonic anhydrase.

      Y        a hydrolase

      E        has lysine in the active site

      E N        a lyase

   E N       has glutamate in the active site

      X        a transferase

      Y        has aspartate in the active site

      Y E        uses acid-base catalysis

      N        has Zn2+ in the active site

      Y N        uses covalent catalysis

      E X        has Mg2+ in the active site

      E N X        uses metal ion catalysis

      Y        does not require a co-factor

      X        uses induced fit catalysis

   Y E N     does not require a coenzyme

   Y N     has histidine in the active site

      X        requires a co-substrate
                 coenzyme

9. The R conformation of Hb is stabilized when ( O2 / CO2 ) binds
( globin / heme ).

Underline the correct choice inside each set of parentheses.

10. Draw isoleucine at pH 7.

I'm not including amino acid structures in this key. Basically 0.5 point for having the backbone with the correct charges and 0.5 point for the side chain.

9. The T conformation of Hb is stabilized when ( O2 / CO2 ) binds
( globin / heme ).

Underline the correct choice inside each set of parentheses.

10. Draw proline at pH 7.

9. The sequence of amino acid residues is the
( primary / secondary ) level of protein structure. This is stabilized by
( covalent bonds / hydrophobic interactions ).

Underline the correct choice inside each set of parentheses.

10. Draw valine at pH 7.

9. The local arrangement of the backbone is the (primary / secondary ) level of protein structure. This is stabilized by
(ionic interactions / hydrogen bonds ).

Underline the correct choice inside each set of parentheses.

10. Draw leucine at pH 7.

 

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