are the fundamental biological components of skin, hair, muscles, connective
tissues, enzymes etc...
are defined as the biopolymers composed of α-amino acids linked by peptide
bonds. They are also known as polypeptides. Proteins are the major constituents
of all living organisms. They contain carbon, hydrogen, nitrogen, oxygen and
are classified into three main groups.
protein that yields only α-amino acids on hydrolysis is called a simple
protein. Examples: albumin and globulin
protein that yields α-amino acids and a non-protein part upon hydrolysis is
called a conjugated protein. The non-protein part is called as the prosthetic
the nature of prosthetic group, conjugated proteins are further classified as
with nucleic acids is called as nucleo protein.
containing phosphoric acid is called as phosphoprotein.
Example: casein (in milk).
containing carbohydrate moiety is called as glycoprotein.
Example: mucin (in saliva)
containing heterocyclic compounds like porphyrins is called as chromo protein.
Example: myoglobin (in muscle).
conjugated with lipids is called lipoprotein.
Examples: chylomicron (in small intestine)
containing metal ion is called as metalloprotein.
Examples: ceruloplasmin (in blood).
that is derived from simple or conjugated proteins by the action of acids,
alkalies or enzyme is called as derived protein. These are partially hydrolysed
is termed as the building block of the body. Protein is vital in the
maintenance of body tissue, including development and repair.
proteins acts as a hormones. Example: Insulin, a small protein, which regulates
blood sugar level.
the enzymes are proteins, they act as biocatalysts in chemical reactions taking
place in the body.
Protein is a major component in
transportation of certain molecules. For example, haemoglobin is a protein that
transports oxygen throughout the body.
Proteins are used to store certain
molecules. Ferritin is a protein which stores iron in the liver.
All antibodies are proteins.
Antibodies neutralize infection, illness and diseases.