TABLE 1.

Identified INTRA-peptide BS³ cross-links in isolated lipid-free apoA-I^Δ185–243 monomeric and dimeric samples derived from mixed ¹⁴N- and ¹⁵N-labeled proteins

Cross-link	Peptides involveda	Mod.b	Sample	Massc
				14N	15N
				Da
Lys88–Lys94	84QEMSKDLEEVKAK96	XL	M	1671.86	1688.81
		XL	D	1671.86	1688.81
Lys12–Lys23	11VKDLATVYVDVLKDSGR27	XL	M	2015.13	2037.07
		XL	D	2015.12	2037.06
Lys23–Ser25	11VKDLATVYVDVLKDSGR27	XL, H	M	2171.22	2193.16
		XL, H	D	2171.21	2193.15
Lys133–Lys140	132QKLHELQEKLSPLGEEMR149	XL	M	2302.24	2329.16
		XL	D	2302.23	2329.15
Lys133–Ser142	132QKLHELQEKLSPLGEEMR149	XL	M	2302.24	2329.16
			D	NDd	ND
Lys140–Ser142	132QKLHELQEKLSPLGEEMR149	XL, H	M	2458.31	2485.24
			D	ND	ND
Lys106–Lys107	97VQPYLDDFQKKWQEEMELYR116	XL	M	2782.39	2811.32
			D	ND	ND

^a Lysines or serines involved in cross-links are in bold type.

^b Mod., chemical modifications; XL, one complete cross-link (+138.068 Da); H, one hydrolyzed cross-linker (+156.079 Da).

^c Experimentally derived monoisotopic mass for each peptide with each isotope and the combinations.

^d ND, not detected. These ions were detectable in one sample (i.e. monomer or dimer) but not in the other.