CH3(CONH)-CHR-(CONH)CH3. Note: the amino and carboxyl groups no longer exist --
ID: 846647 • Letter: C
Question
CH3(CONH)-CHR-(CONH)CH3. Note: the amino and carboxyl groups no longer exist -- they have been converted to amides (CONH represents the amide group). Also note: R represents the Tyr side chain. This compound, then, in this problem, is a substrate for an enzyme.
Recall the pKa of the Tyr side chain in answering this question. At pH 7, which of The Big Three interactions (H bonds; hydrophobic interactions; charge/charge interaction) could be involved in the binding of this compound (that is, of the modified form of Tyr as shown above) to the binding site of the enzyme for which the compound is a substrate?
A. charge/charge only
B. hydrophobic interaction only
C. charge/charge and hydrophobic interaction
D. H bonding and hydrophobic interaction
E. H bonding and charge/charge interaction
Explanation / Answer
E. H bonding and charge/charge interaction