Principles of Biochemistry

5.1.3.2 Classification based on Chemical Nature of Protein

a)Simple Proteins

Many proteins such as the enzymes contain only amino acids and no other chemical groups and they are called simple proteins.

e.g Ribonuclease and Chymotrypsinogen

b)Conjugated Proteins

Some kinds of proteins on hydrolysis yield some other chemical component in addition to amino acid, and they are called conjugated proteins. Conjugated proteins are classified on the basis of the chemical nature of their prosthetic groups.The Prosthetic groups of a protein plays an important role in its biological function.The non amino acid part of a conjugated protein is usually called its prosthetic group.

Types of Conjugated Proteins

Type of proteins	Prosthetic group	Example
Lipoproteins	Lipids	Lipoprotein of blood
Glycoproteins	Carbohydrates	Globulin of blood
Phosphoproteins	Phosphate groups	Casein of milk
Hemoproteins	Heme(iron porphyrin)	Hemoglobin
Flavoproteins	Flavin nucleotides	Succinate dehydrogenase
Metalloproteins	Iron Zinc	Ferritin Alcohol dehydrogenase