Question

A protease active site is shown in the figure below as a space-filled model and as a cartoon. which of the following amino acids would form specific interactions with the active site residue(s)? choose all that apply; all or nothing grading applies. question 18 options:

a) val
b) lys
c) glu
d) cys
e) arg

Answer 1

The amino acids that would form specific interactions with the active site residues are b) lys ,c) glu, and e) arg. Therefore , b) lys ,c) glu, and e) arg is correct .

Amino acids that would form specific interactions:

Lys (b): The positively charged side chain of lysine can form a hydrogen bond with the negatively charged oxygen atom of Asp102.

Glu (c): The negatively charged side chain of glutamate can form a hydrogen bond with the positively charged nitrogen atom of His57.

Arg (e): The guanidinium group of arginine can form a salt bridge with the negatively charged oxygen atom of Asp102.

Amino acids that would NOT form specific interactions:

Val (a): The side chain of valine is a small hydrophobic group that is unlikely to form any specific interactions with the active site residues.

Cys (d): The side chain of cysteine is also a small hydrophobic group that is unlikely to form any specific interactions with the active site residues.

Therefore, the correct answers are b, c, and e.

Here is a more detailed explanation of the specific interactions:

Lysine and Asp102: The hydrogen bond between lysine and Asp102 helps to stabilize the negative charge on Asp102, which is important for the catalytic activity of the protease.

Glutamate and His57: The hydrogen bond between glutamate and His57 helps to deprotonate His57, which is essential for its role as a base catalyst in the proteolytic reaction.

Arginine and Asp102: The salt bridge between arginine and Asp102 helps to position the substrate protein in the active site.