Amino Acids, Proteins and Porphyrins
Albumins and globulins are proteins
Classification of proteins
A. Simple proteins (on complete hydrolysis yield only amino acids)
a. Albumin: - coagulated by Heat and ppt by saturating (full saturation) with Nl-L (salt), deficit in
glycineeg. serum Albumin, Egg albumin, Lactalbumin (milk) Leucosin (cereals wheat) Legumelin
b. Globulins — coagulated by Heat, ppt. by half salt saturation insoluble in water. Eg. serum globulin
Legumin (pea) Tuberin
c. A. Glutamines — rich in glutamic acids egGlutenin (wheat) oryzenin (rice)
B. Prolamines→ soluble in 50-80% alcohol but insoluble in absolute alcohol * rich in proline but
poor in lysine egGliadin (wheat) Zein (maize)
d. Protamines Basic protein do not contains → cysteine Tryptophan and tyrosine but rich in Arginine. * Not coagulated by Heat Egsalmine, sardinine and cyprinine of fish (salmon) sperm and testies
e. Histones →eg globin of HbNucleohistone thymus histones
f. Scieroproteins (Albuminoids) eg Keratin collagen and Elastins
B. Conjugated proteins (simple proteins combines with prosthetic groups):-
a. Nucleoproteins — eg. Nucleoproteins and Nucleohistone
c. Glycoprotein →eg. Mucin,
d. Phosphoprotein→eg. caseinogen (milk), ovovitellin (egg yolk)
e. Metalloproteins→eg. siderophilin (Fe), ceruloplasmin (Cu)
f. Chromoproteins→contain porphyrineg. Hemoglobin (Fe) cyto. Oxidase, catalase, peroxidases.
g. Flavo protein, visual purple
C. Derived Proteins: -
a. Primary derivatives (denaturated protein in which peptide bonds remains intact): eg.
i. Proteins — in early stage of hydrolysis →eg. fibrin from fibrinogen
ii. Metaprotein: (in later stage) →eg. Acid and alkali metaproteins
iii. Coagulated proteins → cooked protein
b. Secondary Derivatives — Due to cleavage of peptides bonds.
i. Proteoses→by action of pepsin or trypsin Eg. Albumose from Albumin, globulose from
ii. B. Peptones →further stage of cleavage than the proteoseseg. proteins product by Enzymatic digestion.
iii. Peptides →eg. di-, tri, and polypeptides.