Table 2.

Oxidized phospholipid-apoprotein cross-link adducts identified in human HDL and in human plasma exposed to MPO−H₂O₂−NO₂⁻ system

HDL (0.5 mg/ml) was incubated with MPO (30 nm), NaNO₂ (500 μm), H₂O₂ (added to 100 μm/h) and DTPA (200 μm) at 37 °C. After 2 h incubation samples were subjected to NaBH₄ reduction, tryptic digestion, peptide enrichment, and LC-MS/MS analysis. Experiments using human plasma were carried out similarly. The MS/MS spectra obtained were searched against a protein sequence database containing major and minor apoproteins of human HDL using Massmatrix search engine to identify oxPL-peptide cross-link adducts as described under “Experimental procedures.”

Cross-linked apoproteins	Cross-linked residues (oxPL type)	Peptides cross-linked by oxPLs		Human HDL	Human plasma
ApoA-I–apoA-I	ApoA-I H135–apoA-I K107 (KODA-PL)	LH$ELQEKLSPLGEEMRa	K$WQEEMELYR	√	-
	ApoA-I H135–apoA-I K107 (KOOA-PL)	VEPLRAELQEGARQKLH$ELQEK	K$WQEEMELYR	-	√
	ApoA-I H162–apoA-I K94 (KOHA-PL)	DLEEVK$AKVQPYLDDFQK	TH$LAPYSDELRQR	√	-
	ApoA-I H162–apoA-I K118 (KOOA-PL)	TH$LAPYSDELR	QK$VEPLR	√	-
	ApoA-I H199–apoA-I K195 (KODA-PL)	LAEYHAK$ATEH$LSTLSEK		√	-
ApoA-I–apoA-II	ApoA-I H135–apoA-II K46 (KOOA-PL)	LH$ELQEK	SK$EQLTPLIK	√	-
	ApoA-I H155–apoA-II K28 (KOHA-PL)	AH$VDALR	DLMEK$VK	-	√
	ApoA-I H155–apoA-II K30 (KOHA-PL)	DLMEKVK$SPELQAEAKSYFEK	DRARAH$VDALR	√	-
	ApoA-I H155–apoA-II K46 (KOOA-PL)	AH$VDALR	SK$EQLTPLIKK	√	-

^a H$ and K$ represent histidine and lysine residues cross-linked by oxPLs.