TABLE 6.

Contribution of residues to the pK_a shifts of Asp-85 in BR and Asp-75 in ASR (relative to the bulk solvent) in the presence of the protonated Schiff base (in pK_a units)

For clarity, residue pairs that are responsible for differences of <0.7 between pK_a(Asp-85) and pK_a(Asp-75) are not listed except for the Glu-204/Asp-198 pair. Side, side chain; bb, backbone.

BR (1C3W)	pKa(Asp-85) = 1.5			ASR (1XIO)	pKa (Asp-75) = −5.1			Difference total
	Side	bb	Total		Side	bb	Total
Ile-52	−0.1	0.0	−0.1	Trp-46	−0.6	−0.3	−0.9	0.8
Ala-53	0.0	−0.5	−0.5	Ser-47	−2.6	−0.6	−3.2	2.7
Tyr-57	−0.5	−0.4	−0.9	Tyr-51	0.2	−0.4	−0.2	−0.7
Arg-82	−3.9	0.8	−3.1	Arg72	−2.1	0.9	−1.2	−1.9
Glu-194	1.2	−0.1	1.1	Ser-188	0.0	0.0	0.0	1.1
Glu-204	0.0	0.1	0.1	Asp-198	0.6	0.0	0.6	−0.5
Asp-212	6.3	−0.1	6.2	Pro-206			−0.1	6.3
Schiff			−9.3	Schiff			−10.3	1.0