ABSTRACT
Enzymes are biological catalysts. They are found both inside and outside of cells,
and these fascinating molecules dramatically accelerate chemical reactions, often
by many orders of magnitude compared to the uncatalyzed reaction. Enzymes are
protein molecules and are very complex. A protein consists of a linear chain of
hundreds of amino acid building blocks, which are produced in the cell, like
beads on a string. Each chain of amino acids folds up into a very specific
compact form, dictated by its linear amino acid sequence. Proteins are composed
of 20 different types of amino acids, and it is the chemical properties of these
amino acids and the interactions between them that dictate the particular
compact form the amino acid sequence will adopt. In this manner, the linear
sequence of the amino acid chain dictates the three-dimensional shape of a
protein and consequently its function. The three-dimensional structure of a
protein determines the location of crucial amino acids and puts them in position
to carry out the function of the protein, such as catalysis of a chemical reaction or
recognition and binding to such molecules as DNA, proteins, hormones, meta-
bolites, or drugs. Some enzymes are composed of multiple protein molecules
that are associated noncovalently in a specific arrangement.