Chemical classifications of proteins

1. Chemical ClassificationChemical Classification
ofof
ProteinsProteins
Class 6Class 6

2. ProteinsProteins
 Organic compoundsOrganic compounds
 Contains C, H,O, N, AND P ,SContains C, H,O, N, AND P ,S
 Mixed polymer of amino acidsMixed polymer of amino acids
 Linked together by peptide bondsLinked together by peptide bonds
N terminal
C terminal
H2N COOH
Polypeptide / Protein
n

3. Classification based on
Chemical
composition

4. Classification based on
Chemical composition
Simple proteins
Conjugated proteins
Derived proteins
Contains only amino acids
Contains amino acids and
non protein part called
prosthetic part
Hydrolysed, degraded or
denatured product of simple
or conjugated protein

5. Simple ProteinsSimple Proteins
 Composed of only amino acids, linked byComposed of only amino acids, linked by
peptide bondspeptide bonds
Albumins
Globulins
Albuminoids /Scleroprotein
Globins
Histones
Prolamines
Protamines
Glutelins

6. Simple ProteinsSimple Proteins
Albumins :
Soluble in water, Heat coagulated , Precipitated at
full saturation
EX: Serum Albumin, Ovalbumin, Lactalbumin
Globulins :
Soluble in water & in dilute salt solutions
Coagulated by heat, Precipitated at half saturation ,
EX: Serum Globulins, Ovoglobulin, Lactglobulin,
Legumin of pea
A
G

7. Simple ProteinsSimple Proteins
Albuminoids / Scleroproteins:
Insoluble in water, Salt solution, Acid, Alkali
Not coagulated by heat , not recipitated
EX: Collagen, Keratin, Elastin,
Globins :
Soluble in water, dilute acid and alkali
Soluble in neutral salt solutions
Not Coagulated by heat, Basic proteins
EX: Globins of Hemoglobin and Myoglobins
A
G

8. Simple ProteinsSimple Proteins
Histones:
Basic prteoins rich in histidine , Soluble
in water, mainly found in association with
nucleic acid and gives stability to the genetic
matterial, not coagulated
EX: Histones of nucleoproteins , Thymus
Protamine :
Soluble in water, Dilute alkali and dilute acid
Not Coagulated by heat Relatively small proteins rich
in Arginine and Lysine
EX: Zinc insulinate, Nucleo protein of sperm ,
Salmine
H
P

9. Simple ProteinsSimple Proteins
Prolamines:
Insoluble in water, soluble in dilute alcohol Not
coagulated by heat EX: Proline rich protein of
plants deficient in lysine
Glutelins :
Insoluble in water, Soluble in salt solutions
Coagulated by heat, Found in plants
EX: Zein of maize /Corn , Gliadin of wheat
P
G

10. Conjugated ProteinsConjugated Proteins
 Proteins linked to non-protein groups calledProteins linked to non-protein groups called
prosthetic groupsprosthetic groups
Glycoproteins
Phosphoproteins
Lipoproteins
Nucleoproteins
Chromoproteins
Metaloproteins
Flevoproteins

11. Conjugated ProteinsConjugated Proteins
Glycoproteins :
Carbohydrate as prosthetic group
EX: Ovomuvin, Ovomucoid, mucoprotein,
Blood group antigen, receptors on cell membrane
Phosphoproteins :
Phosphate / phosphorus as prosthetic group
EX: Casein, Ovo vitelline
G
P

12. Conjugated ProteinsConjugated Proteins
Lipoprotein:
Lipid in association of apoprotein
Lipid is prosthetic group
EX: Chylomicrone, VLDL, HDL, Membrane
lipoproteins, milk
Nucleoprotein :
Nucleic acid or nucleotide as the prosthetic
group
EX: Histones, nucleo protein of thymus & sperm
L
N

13. Conjugated ProteinsConjugated Proteins
Chromoproteins:
Protein in association with coloued prosthetic
group It impart colour to the proteins
EX: Hemoglobin , Visual purple,
Metaloproteins :
Protein in association with metal ions
Metal activates the protein enzymes
EX: Zinc insulinate, Hemoglobin, Myoglobin,
Cytochroome, Carbonic unhydrase, Tyrosinase
C
M

14. Conjugated ProteinsConjugated Proteins
Flavoproteins:
Riboflavin (Vitamin B2) in association with
proteins
EX: Riboflavin yellow (yellow enzyme of whey),
Flavanoids of liver and kidney
F

15. Functions of Conjugated ProteinsFunctions of Conjugated Proteins
HemoglobinHemoglobin HemeHeme Transport of O2 CO2Transport of O2 CO2
CytochromeCytochrome HemeHeme Electron transportElectron transport
RhodopsinRhodopsin RetinalRetinal VisionVision
CaseinCasein PhosphrousPhosphrous Complete proteinComplete protein
LipoproteinLipoprotein LipidLipid Lipid transport & cellLipid transport & cell
membranemembrane
FerritinFerritin IronIron Iron storageIron storage
TransferrinTransferrin IronIron Transport IronTransport Iron
CeruloplasminCeruloplasmin CopperCopper Transport copper, EnzymeTransport copper, Enzyme

16. Derived ProteinsDerived Proteins
 Products obtained by hydrolysis, degradation orProducts obtained by hydrolysis, degradation or
denaturation of simple or conjugated proteinsdenaturation of simple or conjugated proteins
Proteans
Meta-proteins
Coagulated proteins
Proteose
Peptones
Peptides
Primary derived Secondary derived