BIOMOLECULES AND ENZYMES

Detailed explanation-1: -For the simplest amino acid, glycine, pKa1= 2.34 and pKa2 = 9.6, pI = 5.97. The pI will be at a lower pH because the acidic side chain introduces an “extra” negative charge.

Detailed explanation-2: -The isoelectric point (pI) is the pH of a solution at which the net charge of a protein becomes zero. 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.

Detailed explanation-3: -The isoelectric point is the pH at which a particular molecule is electrically neutral due to the equilibrium of positive and negative charges. In proteins and peptides, this depends on the dissociation constant (pKa) of charged groups of seven amino acids and NH+ and COO-groups at polypeptide termini.

Detailed explanation-4: -The isoelectric point (pI) of a protein is defined as the pH at which the net charge of a protein molecule is zero. Accordingly, proteins are positively charged at a pH below their pI and negatively charged at a pH above their pI.