Enzymes are biological catalysts that increase the rate at which chemical reactions occur. Enzyme activity (ability of the enzyme to speed up chemical reaction) is dependent on the environment surrounding the enzyme and the amount of substrate present. This activity will demonstrate how temperature, pH, and substrate concentration affect the activity of the enzyme sucrase.

Sucrase, an enzyme found in the small intestine, catalyzes the splitting of the disaccharide (di= two, saccharide = sugar) sucrose into the monosaccharides glucose and fructose.

Review

Enzymes, large protein molecules produced by cells of the body, are biological catalysts acting on specific substrates to produce products. Enzymes speed up the rate of chemical reactions between substrates without becoming chemically changed in the reaction. Some enzymes anabolize (build) small substrate molecules into large product molecules such as macromolecules. Whereas other enzymes catabolize (breakdown) substrate macromolecules like carbohydrates, lipids, proteins, and nucleic acids into smaller product molecules.

Substrates bind to a specific area of an enzyme called the active site. The shape of the active site determines what substrates can bind to it, just as the shape of a lock determines which key can fit. Therefore, only specific enzymes can bind and act on specific substrates.

Each enzyme has optimal environmental conditions, such as temperature and pH, at which it is the most active.

The optimum pH and temperature for the enzymes in our body correlates with the pH values and temperature at which they work.

Extreme temperatures and pH (temperatures and pH far from optimum) can cause enzymes to become denatured. Denatured enzymes lose their shape and cannot catalyze chemical reactions.