Question

Draw the structure of the following amino acids, at pH 9

i) F

ii) P

iii) H

iv) E

v) C

vi) G

vii) W

viii) L

Answer 1

In the structure if amino acids the carboxyl group (-COO-) has pKa about 2 and the pKa of the amine group (-NH3+) is about 9. Within this pH range i.e. pH 2 to pH 9 the amino acids exists in the zwitter ionic form, the net charge for the protein in zwitter ionic form is zero. This indicates that at strong acidic conditions < pH 2 the amino acids will have +1 charge and at basic condition > pH 9 the amino acids will have -1 charge. structures will be as follows