Identification of a new cross-link and unique histidine adduct from bovine serum albumin incubated with malondialdehyde.
Malondialdehyde, acetaldehyde, acrolein, and 4-hydroxynonenal are all products of fatty acid oxidation found in the fatty streaks of atherosclerotic arteries due to a lack of antioxidants and an increase in glycation products. Previously identified cross-links derived from these molecules have nearly always required more than one molecule of each type, although this is physiologically less likely than a reaction involving a single molecule. Here we provide indirect but strong evidence for a malondialdehyde-derived cross-link requiring just one malondialdehyde molecule to link arginine and lysine, giving 2-ornithinyl-4-methyl(1epsilon-lysyl)1,3-imidazole following a 4-day incubation of albumin with 8 mm malondialdehyde. This cross-link was identified as its partial degradation product Nepsilon-(2-carboxyl,2-aminoethane)-Nepsilon-methanoyl-lysine by NMR and mass spectrometry. Analysis of plasma from treated diabetic patients revealed that one patient levels had as high as 0.46%, 0.67% of their lysine/arginine residues modified by this cross-link, although others had lower levels. Alkaline hydrolysis of serum albumin also revealed two acid-labile malondialdehyde adducts of histidine in significant quantities, the isomers 4- and 2-ethylidene-histidine. These constituted up to 0.93% of the histidines in treated diabetic patients. Although collagen is readily cross-linked by malondialdehyde, none of these particular products could be found in incubations of collagen with malondialdehyde.
Collagen Research Group, Division of Molecular and Cellular Biology, University of Bristol, Bristol BS40 5DS, UK. das55@cam.ac.uk
David A
DA
Slatter
Nicholas C
NC
Avery
Allen J
AJ
Bailey
D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000097:blood; D001665:Binding Sites; D002417:Cattle; D003432:Cross-Linking Reagents / Q000494:pharmacology; D003920:Diabetes Mellitus / Q000097:blood; D006168:Guinea Pigs; D006639:Histidine; D006801:Humans; D008239:Lysine / Q000031:analogs & derivatives / Q000097:blood; D009682:Magnetic Resonance Spectroscopy; D008315:Malondialdehyde / Q000494:pharmacology*; D013058:Mass Spectrometry; D012710:Serum Albumin, Bovine / Q000737:chemistry* / Q000187:drug effects
D003432:Cross-Linking Reagents; D012710:Serum Albumin, Bovine; D006639:Histidine; D008315:Malondialdehyde; D001120:Arginine; D008239:Lysine