title: Facile degradation of apolipoprotein B by radical reactions and the presence of cleaved proteins in serum.
abstract: A facile cleavage of peptide bonds of apolipoprotein B (apoB) by radical reaction is reported. When human LDL was subjected to oxidative damage using Cu2+, extensive degradation of apoB was observed based on immunoblotting. The degradation of apoB was inhibited by radical scavengers (beta-mercaptoethanol, butylated hydroxytoluene, and probucol) and promoted by a radical initiator [2, 2'-azobis(2-amidinopropane)dihydrochloride]. When human serum was treated with Cu2+, a similar cleavage pattern of apoB was observed. The cleaved apoB proteins were also detected in normal serum on the basis of immunoblots. These results suggest that apoB is highly reactive toward radicals in vitro and in vivo, with reaction resulting in the cleavage of peptide bonds.
authors.affiliation: Department of Food Science and Nutrition, Nara Women's University, Nara, 630-8506, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Tanaka
authors.forename: H
authors.initials: H
authors.lastname: Iguchi
authors.forename: S
authors.initials: S
authors.lastname: Taketani
authors.forename: R
authors.initials: R
authors.lastname: Nakata
authors.forename: S
authors.initials: S
authors.lastname: Tokumaru
authors.forename: T
authors.initials: T
authors.lastname: Sugimoto
authors.forename: S
authors.initials: S
authors.lastname: Kojo
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000375:Aging / Q000097:blood; D001055:Apolipoproteins B / Q000097:blood* / Q000276:immunology / Q000378:metabolism*; D003300:Copper / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel / Q000379:methods; D005260:Female; D005609:Free Radicals / Q000378:metabolism; D006801:Humans; D008077:Lipoproteins, LDL / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D008970:Molecular Weight; D010084:Oxidation-Reduction; D010446:Peptide Fragments / Q000097:blood / Q000378:metabolism; D013194:Staining and Labeling / Q000379:methods
chemical_list: D001055:Apolipoproteins B; D005609:Free Radicals; D008077:Lipoproteins, LDL; D010446:Peptide Fragments; D003300:Copper