Enzyme Kinetics - Background
Enzymes are among the most important biological substances present in living organisms. Without enzymes many of the chemical processes in the body would not proceed at a rate fast enough to support life. Enzymes are large organic molecules that act as biological catalysts which are capable of increasing the speed of a reaction. For some enzymes this means increasing the reaction rate by a factor of 1020.
Enzymes are highly selective in that they generally act on only one compound or class of compounds, called the substrate. Although enzymes with old names have various endings, new enzyme names are derived from the substrate name by adding an -ase ending. For example, an enzyme acting on lipids would be called lipase. Like all catalysts, enzymes function by reducing the activation energy of a particular process without being consumed in the process. They accomplish this by binding to the substrate. Since enzymes are usually larger than their substrates, the binding takes place on only part of the enzyme molecule called the catalytic site. Once bound to the substrate, the reaction occurs and the newly formed product is released.
enzyme + substrate 
enzyme-substrate complex enzyme + product
The resulting enzyme is then free to bind to another substrate molecule and the process is repeated. The number of substrate molecules that can be bound and reacted per minute is called the turnover number of the enzyme. Catalase, which decomposes hydrogen peroxide to water and oxygen gas, has a turnover number of five million. This means that in one minute, each enzyme molecule is capable of decomposing five million hydrogen peroxide molecules.
Continue and read about the factors that influence enzyme activity.
