Chymotrypsin

• Chymotrypsin is one of the serine proteases.

• Chymotrypsin is selective for peptide bonds with aromatic or large hydrophobic side chains, such as Tyr, Trp, Phe and Met, which are on the carboxyl side of this bond. It can also catalyze the hydrolysis of easter bond.

• The main catalytic driving force for Chymotrypsin is the set of three amino acid known as catalytic triad. This catalytic pocket is found in the whole serine protease family.

Properties of an Active Site

• A shape that fits a specific substrate or substrates only

• Side chains that attract the enzyme particular substrate

• Side chains specifically positioned to speed the reaction

The Catalytic Triad

Chymotrypsin Protein HydrolysisStage #1

Chymotrypsin Protein HydrolysisStage #2

Chymotrypsin Protein HydrolysisStage #3

Chymotrypsin Protein HydrolysisStage #4

Chymotrypsin Protein HydrolysisStage #5

Chymotrypsin Protein HydrolysisStage #6

Transition State Stabilization

Chymotrypsin Kinetics

The initial "burst" in chymotrypsin-catalysed hydrolysis of the p-nitrophenyl acetate