Outline

Introduction

The Role of Enzymes

Chemical Reaction Rates and the Effects of Catalysts

> Reaction Rates and Reaction Order

> > First-Order Rates: The Rate Constant (Equations 11.1, 11.2, 11.3, 11.4a, 11.4b, Figure 11.1, Eqs. 11.5, 11.6a, 11.6b)

> > Second-Order Reactions (Equation 11.7)

> Transition States and Reaction Rates (Figure 11.2, Eqs. 11.8, 11.9, 11.10, 11.11, Figure 11.3, Eqs. 11.12, 11.13)

> What a Catalyst Does (Figure 11.4, Figure 11.5, Figure 11.6)

How Enzymes Act as Catalysts: Principles and Examples

> General Principles: The Induced Fit Model (Figure 11.7, Figure 11.8, Reaction)

> Triose Phosphate Isomerase (Reaction, Figure 11.9, Reaction, Reactions, Figure 11.10)

> Serine Protease (Table 5.4, Figure 11.11, Figure 11.12, Figure 11.13)

The Kinetics of Enzymatic Catalysis

> Reaction Rate for a Simple Enzyme-Catalyzed Reaction: Michaelis-Menten Kinetics
> (Reaction, Eqs. 11.14, 11.15, 11.16, Figure 11.14, Eqs. 11.17, 11.18, 11.19, 11.20, 11.21, 11.22, 11.23, 11.24, Figure 11.15, Eqs. 11.25, 11.26)

> Expressing Reaction Rates for Multistep Reactions (Reaction, Equation 11.27)

> The Significance of K M, k CAT, and k CAT/K M (Table 11.1, Eqs. 11.28, 11.29, Table 11.2)

> Analysis of Kinetic Data: Testing the Michaelis-Menten Equation (Figure 11.16, eqs. 11.30a, 11.30b, 11.31, 11.32, 11.33, Figure 11.17)

> Multisubstrate Reactions

> > Random Substrate Binding (Scheme #1, #2, #3, #4)

> > Ordered Substrate Binding

> > The "Ping-Pong" Mechanism

> A Closer Look at Some Complex Reactions (Scheme, Eqs. 11.34, 11.35a, 11.35b, 11.35c, Figure 11.18, Table 11.3)

Enzyme Inhibition

> Reversible Inhibition

> > Competitive Inhibition (Figure 11.19, Scheme, Eqs. 11.36, 11.37a, 11.37b, Figure 11.20, Figure 11.21)

> > Noncompetitive Inhibition (Figure 11.22, Scheme, Eqs. 11.38, 11.39, Figure 11.23)

> Irreversible Inhibition (Table 11.4, Figure 11.24)

Coenzymes, Vitamins, and Essential Metals

> Coenzymes and What They Do (Table 11.5, Structure, Figure 11.25, Figure 11.26)

> Metal Ions in Enzymes (Figure 11.27)

The Diversity of Enzymatic Function

> Classification of Protein Enzymes (Table 11.7)

> > 1. Oxidoreductases catalyze oxidation-reduction reactions.
> > 2. Transferases catalyze transfer of functional groups from one molecule to another.
> > 3. Hydrolases catalyze hydrolytic cleavage
> > 4. Lyases catalyze removal of a group from or addition of a group to a double bond, or other cleavages involving electron rearrangement.
> > 5. Isomerases catalyze intramolecular rearrangement.
> > 6. Ligases catalyze reactions in which two molecules are joined.

> Molecular Engineering of New and Modified Enzymes

> > Site-Directed Mutagenesis

> > Hybrid Enzymes (Figure 11.28)

> > Catalytic Antibodies

Nonprotein Biocatalysts: Ribozymes (Figure 11.29, Figure 11.30)

The Regulation of Enzyme Activity: Allosteric Enzymes

> Substrate-Level Control (Reaction)

> Feedback Control (Scheme #1, #2, #3)

> Allosteric Enzymes

> > Homoallostery (Figure 11.32, Figure 11.33)

> > Heteroallostery (Figure 11.34)

> Aspartate Carbamoyltransferase: An Example of an Allosteric Enzyme (Figure 11.35, Figure 11.36, Figure 11.37, Figure 11.38)

Covalent Modifications to Regulate Enzyme Activity

> Pancreatic Proteases: Activation by Cleavage (Figure 11.39, Figure 11.40)

> A Further Look at Activation by Cleavage: Blood Clotting (Figure 11.42)