Abstract:
Proteins are the building blocks of the living cell. They perform a wide range of
functions like enzymatic catalysis, gene regulations, signal transmission etc., and
form an important structural component of cells and tissues. The diversity of their
roles demands a diversity of structures, but each individual protein has a well defined
three dimensional structure.
Proteins are complex polymers composed of amino acids. Amino acids are organic
molecules and have different properties. There are twenty different amino acids. The
sequence of amino acids is unique for each protein. A single protein may contain
one type of amino acid (homopolymer) e.g. actin, or different types of amino acids
(heteropolymer). An amino acid consists of a backbone and a side group. The side
group of one amino acid is different from that of another amino acid. The number of
atoms in a side group of amino acids varies from 1 to 10 (excluding hydrogen atoms).
Hence the number of atoms in a protein depends on its composition and length. Since
the degrees of freedom of a system is proportional to the number of atoms, having a
larger number of atoms increases the complexity of a protein.
