title: Chemical modification of low-density lipoprotein enhances the number of binding sites for divalent cations.
abstract: The EPR technique with paramagnetic Mn(II) ions has been used to probe the negatively charged sites on the surface of modified low-density lipoprotein (LDL). LDL modified in five different ways exhibited increased binding capacity for divalent cations. Enhanced binding is caused by the increase in the number of 'strong' binding sites. The 'strong' sites have been identified to be the aspartic acid and/or glutamic acid carboxyl residues and the 'weak' sites are zwitter-ionic phospholipids. In native LDL the negative groups make 'bonds' with the positive lysyl residues, thus stabilizing the structure. Any deprotonation or modification of the lysine amino groups makes the LDL structure more loose and the amino acid carboxyl groups accessible to divalent cations.
authors.affiliation: Rudjer Bosković Institute, University of Zagreb, Croatia.
authors.forename: G
authors.initials: G
authors.lastname: Pifat
authors.forename: J
authors.initials: J
authors.lastname: Brnjas-Kraljević
authors.forename: G
authors.initials: G
authors.lastname: Jürgens
authors.forename: C M
authors.initials: CM
authors.lastname: Herak-Kramberger
authors.forename: J N
authors.initials: JN
authors.lastname: Herak
mesh_terms: D000107:Acetylation; D001665:Binding Sites; D002413:Cations, Divalent / Q000378:metabolism*; D004578:Electron Spin Resonance Spectroscopy; D006801:Humans; D008077:Lipoproteins, LDL / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D008315:Malondialdehyde / Q000494:pharmacology; D008345:Manganese / Q000378:metabolism; D008745:Methylation; D009439:Neuraminidase / Q000494:pharmacology; D011973:Receptors, LDL / Q000378:metabolism; D012016:Reference Values; D014302:Trinitrobenzenesulfonic Acid / Q000494:pharmacology
chemical_list: D002413:Cations, Divalent; D008077:Lipoproteins, LDL; D011973:Receptors, LDL; D008345:Manganese; D008315:Malondialdehyde; D014302:Trinitrobenzenesulfonic Acid; D009439:Neuraminidase