2.5 - A - Enzymes
Enzymes are a type of protein that catalyze (speed up) chemical reactions without being altered themselves. Each enzyme binds to a substrate, which is then converted to a product. The portion of the enzyme that binds to a substrate is called the active site and is specific to an enzyme. This is called enzyme-substrate specificity.
Each enzymes catalyzes a specific reaction in a cell. Since there are thousands of reactions that occur, it is necessary for cells to produce thousands of enzyme types. When an active site collides with the appropriate substrate, the catalyzed reaction will occur. The rate of each enzyme's activity is dependent on several factors which will be discussed later.
Immobilizing enzymes involves attaching them to materials or forming aggregates that prevent the enzymes from moving around. This allows them to be used in industrial processes ____. Advantages of this include:
Real-world uses of immobilized enzymes include:
Lactose is a disaccharide made up of a glucose and galactose and is naturally found in milk. Lactase is an enzyme that breaks lactose into its component parts. During digestion, lactose is normally broken down by lactase in the small intestine. However, many people cannot produce the enzyme and so are lactose-intolerance.
Lactose-free milk can be produced industrially by harvesting lactase from large yeast cultures and immobilizing it on alginate beads. Milk is then allowed to pass over the beads, which exposes the active sites to the lactose. (see right).
After the milk has passed, it is lactose-free and can be consumed by the lactose-intolerant. As a result of the increased sugar levels, it has a sweeter taste than normal milk.