Why is Tyrosine more acidic than Serine, even though they both are alcohols? Solution Answer: Both the tyrosine and serine are alocohols. They resembles due to the presence of hydroxyl group. Tyrosine Pka value is 9.7 whereas serine Pka value is 14.2 The tyrosine is a phenol and it is more acidic thatn the serine because of the ability of the neighbouring pi system to delocalize the excess electron density of the anion.