Classification of protein according to structure, function ,solubility.

1. Classification of
Proteins
Presented by- Shalini Singh
Roll Number- 09
Session- 2020-22
M.Sc. Biotechnology (1st Semester)

2. Definition of Proteins
• Proteins are the macromolecules that carry out virtually all the cell activities, it is
polymers made of amino acid.
• The term protein was coined by Dutch chemist G.J Mulder and is derived from
Greek word “proteios” which means of first rank
• Proteins are the most versatile macromolecules in living systems and serve crucial
functions in essentially all biological processes.
• They are the molecular tools and machines that make things happen. As
enzymes, proteins vastly accelerate the rate of metabolic reactions; as structural
cables, proteins provide mechanical support both within cells.

3. Classification of Proteins
• Classification based on biological function:-
1. Structural protein- includes keratin and collagens
2. Dynamic or functional protein- include enzymes and respiratory pigments
• Classification based on shaped on protein:-
1. Fibrous protein- water insoluble thread like proteins. Example- Collagen, Keratin, Fibrin
2. Globular protein- Water soluble. Example- Microfilaments and tubulins

4. Classification of Proteins
• Classification based on solubility characteristics:-
1. Simple proteins:- contains only amino acid.
i. Albumins- found in all body cell and blood stream. Example- lactalbumins(found in milk), serum albumin(
found in blood).
ii. Scleroprotein- insoluble in all neutral solvent. Example- Keratin and Collagen.
iii. Histone protein- water soluble which are rich in basic amino acid such as arginine and lysine.
2. Conjugated protein:- contains simple proteins in combination with some none protein components.
i. Glycoproteins- contains various amount of carbohydrates. Example- Glucose and galactose
ii. Lipoproteins- lipid containing proteins.
iii. Nucleoproteins- combination with nucleic acid. Example- DNA and RNA
iv. Phosphoproteins- combination with phosphate group. Example- Casein of milk.

5. Classification of Proteins
• Classification based on structure:-
1. Primary protein - defined as particular sequence of amino acids
found in the proteins. Example- insulin
2. Secondary protein- regular repeating organization of polypeptide
chain. Example- collagen
3. Tertiary protein- refers to more compact structure in which the
helical and non helical regions of polypeptide chains.
4. Quaternary protein- protein that are comprised of two or more
polypeptide chains. Example- hemoglobin

6. Proteins based on structure