1. Which of the following pairs of residues forms a cystine group that helps def
ID: 301194 • Letter: 1
Question
1. Which of the following pairs of residues forms a cystine group that helps define the shape of the binding site for the guanidinobenzoyl group of the covalently bound intermediate?
A. Cys 42 and Cys 58
B. Cys 191 and Cys 220
C. Cys 128 and Cys 232
D. Cys 22 and Cys 157
2. As shown using Ligand Workshop (using the “Neighbor Residues” option), the side chain of which polar amino acid is likely present at the bottom of the binding site for the guanidinobenzoyl group?
A. Ser 217
B. Gly 226
C. Asp 189
D. Ser 190
3. As shown using the CPK rendering style in Protein Workshop, the orbitals of the Asp 189 side chain overlap with ________ to form __________.
A. atom NE of the substrate; an ion pair and/or hydrogen bonds
B. atoms NH1 and NH2 of the substrate; an ion pair and/or hydrogen bonds
C. atom NE of the substrate; only hydrogen bonds
D. atoms NH1 and NH2 of the substrate; only hydrogen bonds
Explanation / Answer
1. (A) Ser 195 nucleophilicaly attacks the substrate to form covalent bond. The Cystine group is formed by Cys 42 and Cys 58 that helps define the shape of the binding site for the guanidinobenzoyl group of covalently bound intermediate.
2. (B) The side chain of Gly 226 is likely to be present at the bottom of the binding site for the guanidibenzoylgroup.
3. (B) The orbitals of the Asp 189 side chain overlap with atom Nh1 and NH2 of the substrate to form an ion pair and/or hydrogen bonds
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.