Question 90949

The enzyme succinic dehydrogenase catalyses the conversion of succinate to
fumarate as given below. Which one of the following compounds would be a likely
competitive inhibitor of this reaction?
(COOH)H2C-CH2(COOH) → (COOH)HC=CH(COOH)
a. (COOH)HC=CH(COOH)
b. (COOH)C≡C(COOH)
c. CH3CH2CH2NH2
d. (COOH)-CH2-(COOH)
13. Treatment of a polypeptide by 2-mercaptoethanol yields two polypeptides that
have the following amino acid sequences:
X: Ala-Phe-Cys-Met-Tyr-Cys-Leu-Trp-Cys-Asn
Y: Val-Cys-Trp-Val-Ile-Phe-Gly-Cys-Lys
Chymotrypsin-catalyzed hydrolysis of the intact polypeptide yields polypeptide
fragments with the following amino acid compositions:
(Ala, Phe) (Asn, Cys2, Met,Tyr) (Cys, Gly, Lys) (Cys2, Leu,Trp2,Val) (Ile, Phe,Val)
Indicate the positions of the disulfide bonds in the original polypeptide. Cysteines are
numbered in order (C1, C2, C3 in X; and C4, C5 in Y).