TABLE 2.

MALDI-TOF analysis of Endo H-treated and untreated SOSIP.681_GnTl−/−

N-Glycan postitiona	Env region	Peptide sequenceb	Mockc native conditions	PNGaseFd denaturing conditions	EndoHe denaturing conditions	EndoHe native conditions
88	C1	HNVWATHACVPTDPNPQEIPLENVTEEFNMWK	−	−	HexNAc	HexNAc
130 and 136	V1	LAPLCVTLNCTDVTNVTDVSGTR	−	2N→D	2HexNAc	2HexNAc
146 and 156	V2	GNITIMKEMEGEIKNCSFNMATEIR	−	2N→D	2HexNAc	2HexNAc
188 and 193	V2	LDVVPINQGNSSSKNSSEYR	−	2N→D	2HexNAc	2HexNAc
197	C2	LISCNTSAITQACPK	+	N→D	HexNAc	HexNAc
234	C2	DKEFNGTGECK	−	N→D	HexNAc	HexNAc
241	C2	NVSTVQCTHGIKPVVSTQLLLNGSLAEEK	−	2N→D	2HexNAc	2HexNAc
276	C2	IRTENITNNAK	−	N→D	HexNAc	HexNAc
301	V3	ISCTRPNNNTR	−	N→D	HexNAc	HexNAc
448	C4	CESNITGLLLTR	−	N→D	HexNAc	HexNAc
463	V5	DGGEEKNSTNEIFRPGGGDMR	−	N→D	HexNAc	HexNAc
611 and 616	gp41 loop	LICTTNVPWNSSWSNK	−	N→D	HexNAc	HexNAc
625	HR2	SQDEIWNNMTWLQWDK	−	N→D	HexNAc	HexNAc
637	HR2	EISNYTNLIYSLIEESQNQQEK	−	N→D	HexNAc	HexNAc

^a Numbering according to the HxB2 sequence.

^b Potential N-linked glycosylation sites are indicated in bold and underlined.

^c Mock-treated SOSIP.681_GnTl−/−; “−” indicates that the peptide was not found, which suggests the peptide is glycosylated and hence not detectable in the MALDI-TOF analyses; “+” indicates that an (unglycosylated) peptide variant was detected.

^d PNGaseF-treated SOSIP.681_GnTl−/−; “N→D” indicates that one asparagine in the peptide was deamidated, indicative of prior glycosylation and subsequent removal by PNGaseF; “2N→D” indicates that two asparagines in the peptide were deamidated.

^e EndoH-treated SOSIP.681_GnTl−/−; “HexNAc” indicates that the peptide was found with an additional HexNAc (i.e. GlcNAc) attached, indicative of glycosylation and subsequent glycan removal by EndoH; “2HexNAc” indicates that two HexNAc moieties were present on the peptide.