Table 3.

ESI LC-MS^E peptide mapping analysis: Identification of urease cysteine residues modified by V21H4-(PEG)₂-Cys.

Conjugation sites searched from the urease side
Urease peptide	Conjugation site	Calculated mass (Da)	MS/MS b/y Possible	MS/MS b/y found	Intensity	Mass match error (ppm)	% of conjugation
1:T010*	UC59-VC136	2,784.2053	28	10	335045	2.6	2.6
1:T026*	UC207-VC136	1,939.6624	12	0	10296	1.9	0.6
1:T063*	UC663-VC136	2,316.7554	18	4	46812	2.9	4.2
1:T081*	UC824-VC136	2,633.1372	26	13	495879	2.1	26.7
Conjugation sites searched from the antibody side
V21H4 C-term peptide	Conjugation site	Calculated mass (Da)	MS/MS b/y possible	MS/MS b/y found	Intensity	Mass match error (ppm)	% of conjugation
2:T012	na	837.2446	16	2	10403	−3.9	0.4
2:T012*	-UC824	2,633.1472	16	7	1609854	1.2	59.1
2:T012*	-UC663	2,784.2153	16	5	726682	1.6	26.7
2:T012*	-UC59	2,316.7654	16	4	343529	−1.4	12.6
2:T012*	-UC207	1,939.6724	16	0	33038	−3.6	1.2

na, not applicable.

*indicates the modified version of the peptide.