Which of the following is having Maximum buffering capacity
(A) Histidine (B) Cysteine (C) Tyrosine (D) Arginine
(A) Answer-A- HistidineMaximum buffering capacity occurs at a pH equal to the pKa, So amino acid which has pKa range near physiologic pH can act as an effective buffer * lmidazole group of histidine - 6.5- 7.4 pKa range * SH group of cysteine- 8.5-9.0 pKa range * OH group of tyrosine - 9.5-10.5 pKa range* Arginine - > 12