Consider the net charge and isoelectric point of an amino acid with an un-ionizable side group.
(a) Identify the amino acids that lack an ionizable R-group (Group I).
For an amino acid with a side (R-) chain that cannot ionize, derive a general expression in terms of measured pH and known pK_a values of a-carboxyl (p^c_a) and a-amino (pK^a_a), respectively, for: 

(b) The deprotonation ratio of the a-carboxyl group

(c) The fraction of un-ionized weak-acid a-carboxyl group in solution
(d) The positive charge of the amino acid group
(e) The fraction of ionized weak base a-amino group in solution
(f) The net charge of the amino acid
(g) The isoelectric point of the amino acid

(h) Using the result in part (f), estimate the isoelectric point of glycine (pK^c _d = 2:36 and pK^a_a = 9:56). Compare this with the reported value of the pI.