Understanding how Triclosan functions requires some rudimentary knowledge of biology, namely the interactions of cell membranes, fatty acids, and enzymes.
The cells of all organisms, including bacteria, require a cell membrane to survive. The cell membrane is a critical barrier that selectively allows oxygen, nutrients, and wastes to permeate and leave the cell (Campbell 106); it is the "edge of life, the boundary that separates the living cell from its nonliving surroundings" (Campbell 130). Without a permeable cell membrane, a cell would simply die. For example, wastes would not be transported out of the cell, causing toxins to accumulate and poison the cell. Curiously, it is precisely this function of the cell membrane that Triclosan is engineered to immobilize.
Cell Membrane Structure
The lipid bilayer holds the cell membrane together. Lipids, or fatty acids, are long hydrocarbon chains essential to cell membrane growth and function. Triclosan immobilizes the cell membrane by stopping the process that elongates these chains.
Triclosan stops the fatty acid elongation process by inhibiting a bacterial enzyme. An enzyme is a protein that catalyzes, or speeds up, a chemical reaction. In a catalyzed reaction, the reactant molecule is called a substrate. The substrate binds to the enzyme's active site, which is shaped like a pocket or groove. The binding can be thought of as a handshake, a key entering a lock (Campbell 93), or puzzle pieces fitting together. Competitive inhibitors are molecules that "steal" the spots of designated substrate molecules (Campbell 94). Once applied to the hands in the form of antibacterial soap, Triclosan acts as a competitive inhibitor, and a battle between Triclosan and bacteria for active sites ensues.
Competitive Inhibition
By stealing active sites from the natural substrate, Triclosan systematically kills bacteria by stopping fatty acid chain growth. This, in turn, stops the growth of the cell membrane and effectively kills the cell. The process is efficient, insidious and almost perfect, and when given the opportunity, Triclosan is extremely successful. The following description of how Triclosan works should be more meaningful now that relevant terms and processes have been introduced.
