Question

Caesin of milk is

• A. Glycoprotein
• B. Lipoprotein
• C. Phosphoprotein
• D. Mucoprotein

Answer 1

The correct option is C Phosphoprotein

Many proteins such as the enzymes ribonuclease and chymotrypsinogen contain only amino acids and no other chemical groups; these are considered simple proteins. However, some proteins contain chemical components in addition to amino acids; these are called conjugated proteins. The non-amino acid part of a conjugated protein is usually called its prosthetic group. Conjugated proteins are classified on the basis of the chemical nature of their prosthetic groups, e.g., lipoproteins (like lipoproteins of blood) contain lipids, glycoproteins (like immunoglobulins) contain carbohydrates, phosphoproteins (like casein of milk) contain phosphorous and metalloproteins (like ferritin, alcohol dehydrogenase, calmodulin etc) contains metals like iron, zinc, calcium etc.