Physical and chemical properties of protein

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  1. Most protein are colorless amorphous substance with no definite melting points or boiling points. On heating they undergo decomposition. 
  2. They forms important part of buffer system of body fluid as they are amphoteric in nature. This is due to large number of ionizable R-groups. 
  3. Isoelectric Point : This is because of presence on the protein chain of additional acidic or basic groups that are not involved in peptide linkages. Most proteins show minimum solubility and stability at their Isoelectric Point. 
  4. Precipitation / coagulation : proteins are easily precipitated by certain agents. Many of the normal function in body are essential precipitation reaction example clotting of blood. Precipitation of protein is an irreversible change and precipitated protein is said to be denatured. 
  5. Colloidal nature : These form colloidal dispersion in water. The inability of proteins to pass through a membrane is of great importance in body. Protein present in bloodstream can't pass through membranes and should remain in the blood stream.  
  6. Oxidation : They oxidised on burning and putrefaction . The product include nitrogen, amines, carbon dioxide and water.  The bad smell produced during putrefaction of dead animals is largely due to formation of amines and other nitrogen products by the bacterial oxidation of body proteins.
  7. Denaturation : loss of biological functioning and tertiary structure by extreme changes in temperature, pH, chemicals.
  8. Hydrolysis : Proteins can hydrolysed by Acid,alkalies,enzymes.The final product of hydrolysis is amino acid. 
  9. Reactivity : These react with a variety of inorganic ions, chemical groups and organic molecules due to presence of different reactive groups on side chains of amino acids of proteins. 


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