HN-CH 8.5 3.9 COOH T 5.7 6.5 07.6 | CH T CIN CICH H IN +ZH -N CH COO- I HN-CH | 16 pK = 1.8 CH | CIN H IN +NH CIN CH COO- I HN-CH 11 = 6.0 pK = CH H CIN CIN H N=CH COO HN-CH I 2 PK3 = 9.2 CH H CIN Above is shown the ionization states and pKas for the amino acid histidine (His). Histidine has three different ionizable functional groups. What is the isoelectric point (pl) of histidine, from the values above? H -N CH