. 2014 May 1;136(21):7643–7654. doi: 10.1021/ja413174b

Table 2. pK_a Values for Inactivation at High pH for Semisynthetic KSI Tyr16 Variants from pH Dependencies of Activity with Subsaturating (pK_a^E,2) and Saturating (pK_a^E·S,2) 5(10)-EST^a.

residue at position 16	side chain solution pK_a^b	pK_a^E,2 (subsaturating)	pK_a^E·S,2 (saturating)
Tyr (WT)	9.95	10.00 ± 0.04	10.06 ± 0.12
2-F-Tyr	9.28	9.58 ± 0.08	10.38 ± 0.07
3-F-Tyr	8.81	9.84 ± 0.07	10.09 ± 0.10
2,6-F₂-Tyr	8.35	9.58 ± 0.04	10.28 ± 0.06
3-Cl-Tyr	8.48	9.71 ± 0.12	9.60 ± 0.08

Values are from fits to data in Figure S3 (Supporting Information) and are shown together with standard errors from regression analysis.

The side chain solution pK_a values are for the corresponding phenols.^86,87

Table 2. pKa Values for Inactivation at High pH for Semisynthetic KSI Tyr16 Variants from pH Dependencies of Activity with Subsaturating (pKaE,2) and Saturating (pKaE·S,2) 5(10)-ESTa.