Answer Happy

• pKa of the side chain R-groups: D (3.9), E (4.2), H (6.0)' C (8.3), Y (10.1), K (10.5), and R (12.5). •pka of amino acids a-amino group (9.6) and a-carboxyl group (2.1). • pKa of N-terminal oligopeptide a-amino group (7.4) and C-terminal a-carboxyl group (3.6).
1. If the Asp ¹02 is replaced with Asn in trypsin, the enzyme activity is reduced by 10,000-fold. • a) On the basis of your knowledge of the catalytic triad structure in trypsin, suggest a structure for the "uncatalytic triad" of Asn-His-Ser in this mutant; • b) Explain why the structure you have proposed explains the reduced activity of the mutant; • c) Discuss the importance of histidine of the catalytic triad in enzyme; • d) State the specificity exhibited by the serine proteases trypsin, chymotrypsin, and elastase, and explain how this specificity is determined by the protein.