Formation of N-formylkynurenine suggests the involvement of apolipoprotein B-100 centered tryptophan radicals in the initiation of LDL lipid peroxidation.
Tryptophan oxidation products were determined in pronase E digests of apo B of delipidated, native and Cu2+ oxidized LDL using a sensitive and specific HPLC method. Oxidized LDL contained N-formylkynurenine, kynurenine and tryptamine but no oxindolylalanine and 5-hydroxytryptophan. N-Formylkynurenine increased from an initial value of 0.21 to 1.67 mol/mol apo B within 5 h. Apo B of native LDL also contained kynurenine (0.80 mol/mol) and tryptamine (0.13 mol/ mol). The results support the assumption that oxidation of Trp residues in apo B is an early event and possibly an elementary reaction involved in initiating LDL oxidation.
Giessauf
A
A
Institute of Biochemistry, University of Graz, Graz, Austria.
van Wickern
B
B
Simat
T
T
Steinhart
H
H
Esterbauer
H
H
D001055:Apolipoproteins B / Q000737:chemistry / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D003300:Copper / Q000378:metabolism; D005609:Free Radicals; D006801:Humans; D007737:Kynurenine / Q000031:analogs & derivatives* / Q000096:biosynthesis / Q000378:metabolism; D015227:Lipid Peroxidation; D008077:Lipoproteins, LDL / Q000378:metabolism*; D010084:Oxidation-Reduction; D011402:Pronase / Q000378:metabolism; D014364:Tryptophan / Q000737:chemistry / Q000378:metabolism*
D001055:Apolipoproteins B; D005609:Free Radicals; D008077:Lipoproteins, LDL; C007772:N'-formylkynurenine; D007737:Kynurenine; D003300:Copper; D014364:Tryptophan; D011402:Pronase