Flashcards in Chapter 9.1 Terms Deck (10):
Is the free energy released in the formation of a large number of weak interactions between the enzyme and the substrate.
Structural changes in both the enzyme and the substrate that facilitate catalysis, upon binding.
The active site contains a reactive group, usually a powerful nucleophile, that become temporarily covalently attached to a part of the substrate in the course of catalysis. An example would be chymotrypsin.
A molecule other than water plays the role of a proton donor or acceptor. Chymotrypsin uses a histidine residue as a base catalyst to enhance the nucleophilic power of serine, whereas a histidine residue in carbonic anhydrase facilitates the removal of a hydrogen ion from a zinc-bound water molecule to generate hydroxide ion.
General acid-base catalysis
The reaction rate is considerably enhanced by brining the two substrates together along a single binding surface on an enzyme.
Catalysis by approximation
A metal ion may facilitate the formation of nucleophiles such as hydroxide ion by direct coordination. A metal ion may also serve as an electrophile, stabilizing a negative charge on a reaction intermediate.
Metal ion catalysis
The modification of a residue to determine reactivity and catalytic relationships. Was used to determine that serine residue plays a central role in the catalytic mechanism of chymotrypsin.
Chemical modification reaction
The constellation of Asp 102, His 57, and Ser 195 residues.
This structure stabilizes the tetrahedral intermediate of the chymotrypsin reaction.