Figure 6.

Characterization of multiple protein components of LDL exposed to the MPO-H₂O₂-NO₂^– system. LDL samples prepared for Figure 5 were analyzed for nitrotyrosine content (a) tryptophan fluorescence (b), unmodified N^ε-lysine groups (c), and lipoprotein REM (d), as described in Methods. Under the conditions used, the REM for exhaustively acetylated LDL is 3.8. Data represent the mean ± SD of 3 independent experiments (1 using ¹²⁵I-labeled LDL as starting material, and 2 using nonlabeled LDL as starting material). + NO₂^– (filled circles), LDL modified by MPO, an H₂O₂-generating system (GGOx), and NO₂^– as described in Figure 5; – NO₂^– (open circles), LDL modified by MPO and an H₂O₂-generating system (GGOx) as described in Figure 5.