BIOMOLECULES AND ENZYMES

Detailed explanation-1: -In an electric field, the amino acid migrates towards cathode when pH is below the isoelectric point while it migrates towards ‘anode when pH is higher than isoelectric point.

Detailed explanation-2: -When pH is less than pI, there is an excess amount of H+ in solution. The excess H+ is attracted to the negatively charged carboxylate ion resulting in its protonation. The carbohydrate ion is protonated, making it neutral, leaving only a positive charge on the amine group.

Detailed explanation-3: -At low pH, the amino acid is protonated at both the amine and carboxyl functions. At this pH it carries a net positive charge and can be treated as a diprotic acid, an acid with two pKa’s. At high pH, both the carboxyl and amine groups are deprotonated.

Detailed explanation-4: -Cations move towards cathode and when pH < PI, thus cationic form dominates.

Detailed explanation-5: -At solution pH that is above the pI, the surface of the protein is predominantly negatively charged, and therefore like-charged molecules will exhibit repulsive forces. Likewise, at a solution pH that is below the pI, the surface of the protein is predominantly positively charged, and repulsion between proteins occurs.