Basic structure of protein

The word protein is derived from Greek word, “proteios” which means primary. As the name shows, the proteins are of paramount importance for biological systems.

Amino acids are the building blocks of proteins. Amino acids can combine to form long linear chains known as polypeptides. Proteins are nothing more than long polypeptide chains.

Proteins are synthesized by polymerization of amino acids through peptide bonds. Two amino acids combined to form a dipeptide; three amino acids form a tripeptide; four will make a tetrapeptide; a few amino acids together will make an oligopeptide; and combination of 10-50 amino acids is a polypeptide.

Chains that are less than 40-50 amino acids or residues are often referred to as polypeptide chains since they are too small to form a functional domain. Larger than this size, they are called proteins.

Most organisms use 20 naturally-occurring amino acids to build proteins. The linear sequence of the amino acids in a protein is dictated by the sequence of the nucleotides in an organisms’ genetic code.

Proteins come in various sizes and shapes. Those with thread-like shapes, the fibrous proteins, tend to have structural or mechanical roles. Those with spherical shapes, the globular protein, function as enzymes, transport proteins, or antibodies. Fibrous proteins tend to be water-insoluble while globular protein’s tend to be water soluble.

The structure, function and general properties of a protein are all determined by the sequence of amino acids that make up its primary sequence.

Proteins are used for body building; all the major structural and functional aspects of the body are carried out by protein molecules. Abnormality in protein structure will lead to molecular diseases with profound alterations in metabolic functions.
Basic structure of protein