title: Analysis of site-specific N-homocysteinylation of human serum albumin in vitro and in vivo using MALDI-ToF and LC-MS/MS mass spectrometry.
abstract: Elevated levels of homocysteine (Hcy) are associated with cardiovascular and neurodegenerative diseases in humans. Hcy becomes a component of human proteins as a result of N-homocysteinylation of protein lysine residues by Hcy-thiolactone, which affects the protein's structure and function, and contributes to Hcy-related pathology. Albumin is the major target for N-homocysteinylation in human blood in vivo. Previous work has identified Lys-525 as a predominant site of N-homocysteinylation in vitro and in vivo. Here we show that Lys-4, Lys-12, Lys-137, Lys-159, Lys-205, and Lys-212 of human albumin are susceptible to N-homocysteinylation in vitro and provide evidence that two of those residues, Lys-137 and Lys-212, in addition to Lys-525, are N-homocysteinylated in vivo in human plasma.
authors.affiliation: Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, Poznań, Poland. lukasmar@ibch.poznan.pl
authors.forename: Lukasz
authors.initials: L
authors.lastname: Marczak
authors.forename: Marta
authors.initials: M
authors.lastname: Sikora
authors.forename: Maciej
authors.initials: M
authors.lastname: Stobiecki
authors.forename: Hieronim
authors.initials: H
authors.lastname: Jakubowski
mesh_terms: D000595:Amino Acid Sequence; D002853:Chromatography, Liquid / Q000379:methods; D006710:Homocysteine / Q000031:analogs & derivatives / Q000097:blood / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D008239:Lysine / Q000378:metabolism; D012709:Serum Albumin / Q000378:metabolism*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods; D053719:Tandem Mass Spectrometry / Q000379:methods
chemical_list: D012709:Serum Albumin; D006710:Homocysteine; C007957:homocysteine thiolactone; D008239:Lysine