Glutamic acid has lower isoelectric point while glutamine `H_(2)N-overset(overset(O)(||))(C)-CH_(2)-CH_(2)- underset(underset(NH_(2))(|)) overset(overset(H)(|))(C)-COOH` has higher isoelectric `pH`. Explain ?

Answer

Glutamic acid undergoes deprotionation as :
`HOOC-CH_(2)-CH_(2)-underset(underset(NH_(3))(|)) overset(overset(H)(|))(C)-COO^(Theta) hArr .^(Theta)OOC -underset(+H^(+))(CH_(2))-CH_(2)-underset(underset(.^(oplus)NH_(3))(|)) overset(overset(H)(|))(C)-COO^(Theta)`
In order to supress the above ionization so that zwritter ion predominate, higher `[H^(+)]` will have to the maintaned and there for isoelectric `pH` will be lower. Glutamine is a monocarboxylic acid and hence no extra `H^(+)` is released to supress above type of ionization and hence isoelectric `pH` is higher.

Explanation

Glutamic acid undergoes deprotionation as :
`HOOC -CH_(2)-CH_(2)- underset(underset(NH_(3))(|))overset(overset(H)(|))(C)-COO^(Theta) hArr .^(Theta)OOC- underset(+H^(+))(CH_(2))- underset(underset(oplusNH_(3)"alanine")(|))overset(overset(H)(|))(C)-COO^(Theta)`
In order o supress the above ionixation so that predominate, higher `[H^(+)]` will have to be maintaned and there for isoelectric `pH` will be lower. Glutamine is a monocarboxyliv acid and hence no extra `H^(+)` os released to supress above type of ionization and hence isoelectric `pH` is higher.