Table 2.

Relative occurrence of side-chain hydrogen bonds between selected pH-sensitive residues

Acceptor	Donor	% pH 4 (1)	% pH 4 (2)	% pH 4 (3)	% pH 4 (4)	% pH 8 (1)	% pH 8 (2)	% pH 8 (3)	% pH 8 (4)
Asp242	Asp194a	64.62	74.21	70.36	64.32	0	0	0	0
Asp242	Arg114pro	0	0	0	0.15	30.80	0	0	7.60
Asp242	Arg116pro	3.40	8.05	9.00	3.75	1.25	63.80	4.75	0
Asp242	Lys117prob	21.15	15.85	0	0.05	7.25	34.70	24.69	19.94/17.04c
Asp242	Ser335	20.94	9.80	26.19	20.59	0.15	50.17	23.39	0
Asp242	His240	1.20	3.05	6.85	4.10	0	0	0.75	2.20
Asp194	Arg114pro	0	0	0	0	9.05	15.05	0.10	0.20
Asp194	Arg116pro	0.20	0.85	0.30	0.85	19.60	22.75	49.58	50.07
Asp194	Ser335	0.10	0.15	4.85	0.60	56.77	1.10	20.79	72.21

Four respective MD simulations at pH 4 or pH 8 were carried out.

^aDenotes donor functionality only in protonated state (pH 4).

^bInteraction with NH backbone.

^cInteraction with side chain amine.