( c ) Tertiary structure The folding and superimposition of polypeptide chains forms a compact globular shape , termed as tertiary structure . It is stabilised by covalent , ionic , hydrogen and disulphide bonds .
The precise arrangement constitutes the quaternary structure .
Classification on the Basis of Hydrolysis Products
( i ) Simple These yield only a-amino acids upon hydrolysis . e . g ., albumin .
( ii ) Conjugated proteins These yield α-amino acids and non-protein part , called prosthetic group .
Protein Nucleoproteins
Prosthetic group
Nucleic acid Phospho proteins Phosphoric acid Glycoproteins Metalioproteins
Carbohydrates Metals
Lipoproteins
Lipids
( iii ) Derived proteins These are obtained by partial hydrolysis of simple or conjugated proteins .
Proteins → Proteoses → Peptones → Polypeptides
Classification on the Basis Functions
1 . |
Structural proteins Fibrous proteins |
2 . |
Enzymes Serve as biological catalyst e . g ., pepsin , trypsin etc . |
3 . |
Hormones Insulin |
4 . |
Contractile proteins Found in muscles , e . g ., myosin , actin . |