title: An online nano-LC-ESI-FTICR-MS method for comprehensive characterization of endogenous fragments from amyloid β and amyloid precursor protein in human and cat cerebrospinal fluid.
abstract: Amyloid precursor protein (APP) is the precursor protein to amyloid β (Aβ), the main constituent of senile plaques in Alzheimer's disease (AD). Endogenous Aβ peptides reflect the APP processing, and greater knowledge of different APP degradation pathways is important to understand the mechanism underlying AD pathology. When one analyzes longer Aβ peptides by low-energy collision-induced dissociation tandem mass spectrometry (MS/MS), mainly long b-fragments are observed, limiting the possibility to determine variations such as amino acid variants or post-translational modifications (PTMs) within the N-terminal half of the peptide. However, by using electron capture dissociation (ECD), we obtained a more comprehensive sequence coverage for several APP/Aβ peptide species, thus enabling a deeper characterization of possible variants and PTMs. Abnormal APP/Aβ processing has also been described in the lysosomal storage disease Niemann-Pick type C and the major large animal used for studying this disease is cat. By ECD MS/MS, a substitution of Asp7 → Glu in cat Aβ was identified. Further, sialylated core 1 like O-glycans at Tyr10, recently discovered in human Aβ (a previously unknown glycosylation type), were identified also in cat cerebrospinal fluid (CSF). It is therefore likely that this unusual type of glycosylation is common for (at least) species belonging to the magnorder Boreoeutheria. We here describe a detailed characterization of endogenous APP/Aβ peptide species in CSF by using an online top-down MS-based method.
authors.affiliation: Clinical Neurochemistry Laboratory, Institute of Neuroscience and Physiology, Department of Psychiatry and Neurochemistry, Sahlgrenska Academy at University of Gothenburg, Mölndal, Sweden. gunnar.brinkmalm@neuro.gu.se
authors.forename: Gunnar
authors.initials: G
authors.lastname: Brinkmalm
authors.forename: Erik
authors.initials: E
authors.lastname: Portelius
authors.forename: Annika
authors.initials: A
authors.lastname: Öhrfelt
authors.forename: Niklas
authors.initials: N
authors.lastname: Mattsson
authors.forename: Rita
authors.initials: R
authors.lastname: Persson
authors.forename: Mikael K
authors.initials: MK
authors.lastname: Gustavsson
authors.forename: Charles H
authors.initials: CH
authors.lastname: Vite
authors.forename: Johan
authors.initials: J
authors.lastname: Gobom
authors.forename: Jan-Eric
authors.initials: JE
authors.lastname: Månsson
authors.forename: Jonas
authors.initials: J
authors.lastname: Nilsson
authors.forename: Adnan
authors.initials: A
authors.lastname: Halim
authors.forename: Göran
authors.initials: G
authors.lastname: Larson
authors.forename: Ulla
authors.initials: U
authors.lastname: Rüetschi
authors.forename: Henrik
authors.initials: H
authors.lastname: Zetterberg
authors.forename: Kaj
authors.initials: K
authors.lastname: Blennow
authors.forename: Ann
authors.initials: A
authors.lastname: Brinkmalm
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D016229:Amyloid beta-Peptides / Q000134:cerebrospinal fluid* / Q000737:chemistry; D016564:Amyloid beta-Protein Precursor / Q000134:cerebrospinal fluid* / Q000737:chemistry; D000818:Animals; D002415:Cats; D002853:Chromatography, Liquid / Q000379:methods*; D006031:Glycosylation; D006801:Humans; D047468:Immunoprecipitation; D008969:Molecular Sequence Data; D016415:Sequence Alignment; D020539:Sequence Analysis, Protein / Q000379:methods*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*
chemical_list: D016229:Amyloid beta-Peptides; D016564:Amyloid beta-Protein Precursor