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LDL nitration induced protein unfolding
Author(s) -
Hamilton Ryan T,
Asatryan Liana,
Cadenas Enrique,
Hsiai Tzung K
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.6.a853-b
Subject(s) - peroxynitrite , chemistry , in vivo , nitration , nitrotyrosine , in vitro , biochemistry , enzyme , superoxide , organic chemistry , biology , nitric oxide synthase , microbiology and biotechnology
Minimally modified (oxidized) LDL (oxLDL) is known to be atherogenic. OxLDL in vivo harbors both unfolded α‐helical structures and elevated lipid peroxides. We hypothesized that the presence of peroxynitrite (ONOO − ) induced LDL protein nitration, leading to an unfolded protein structure similar to oxLDL in vivo. Materials and Results: LDL was treated with Copper (Cu ++ ) at 40μM, ONOO − at 100μM, or PLA2 at 50ng/ml, followed by density ultracentrifugation. ONOO − ‐treated LDL yielded the highest level of nitrotyrosine (3.73±1.37‐fold increase, P < 0.05, n=5), Cu ++ ‐treated LDL yielded the highest level of both oxLDL (by HPLC: 10.96±0.34 fold increase) and lipid peroxides (12.78±3, 10‐fold increase), whereas PLA2 treatment yielded the lowest level of nitrotyrosine and lipid peroxides. Furthermore, oxLDL in vivo and in vitro yielded (25.7±0.3%, n=3, and 23.5±1.0%, n=3) of α‐helical structure compared to (86.5±2.3%, n=3, and 92.8±1.3%, n=3) in native LDL ( P < 0.001, n=3). Conclusions: Our findings suggest that ONOO − ‐mediated lipid modification and post translational protein modification contribute to protein unfolding similar to oxLDL structure in vivo.