This lecture covers the fundamental concepts of enzymes, including enzymatic catalysis, Michaelis-Menten model, and transitional states. It explores examples of enzyme-catalyzed reactions, such as isomerization and hydration, highlighting the role of enzymes in accelerating biochemical reactions. The lecture delves into the calculation of equilibrium constants and free energy changes in enzymatic reactions, emphasizing the importance of enzyme-substrate interactions. Additionally, it discusses enzyme inhibition and the specificity of antibodies, shedding light on the catalytic strategies employed by enzymes to regulate biological processes.