What an enzyme is, the active site and the lowering of activation energy. Then how temperature, pH, substrate and inhibitors change the rate, the six classes of enzyme, and cofactors, coenzymes and prosthetic groups.
3 lessons, about 1 h 25 min3 simulations10 problems3 practice questionsPython in every lesson
Created by StemPy LabEnzymes are biological catalysts, almost all of them proteins. A substrate fits the active site, forms an enzyme-substrate complex and passes through a transition state to the product. The enzyme lowers the activation energy and is not used up.
Each enzyme has an optimum temperature and pH. Cold makes it inactive but heat denatures it. The rate rises with substrate up to a maximum, Vmax, and Km is the substrate level at half Vmax. A competitive inhibitor looks like the substrate and blocks the active site.
Enzymes fall into six classes: oxidoreductases, transferases, hydrolases, lyases, isomerases and ligases. Many enzymes need a non-protein cofactor: a prosthetic group, a coenzyme or a metal ion. The protein part is the apoenzyme, and apoenzyme with cofactor is the holoenzyme.
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