title: Formation of oligomers in the early phase of pH-induced aggregation of the Alzheimer Aβ(12-28) peptide [corrected].
abstract: The early phase in the aggregation process of the Alzheimer's peptide Aβ(12-28) with both protected and unprotected ends was studied by time-resolved infrared spectroscopy and circular dichroism spectroscopy. Aggregation in the time-resolved experiments was initiated by a rapid pH drop caused by the photolysis of 1-(2-nitrophenyl)ethyl sulfate (caged sulfate). The infrared spectra indicate aggregates from both versions of the Aβ(12-28) peptide. [corrected] They form fast (within 60 ms), presumably from initial aggregates, and their spectral signature is consistent with a β-barrel structure. The other type arises relatively slowly from unstructured monomers on the seconds-to-minutes time scale and forms at lower pH than the first type. These β sheets are antiparallel, planar, and large and show an absorption band at 1622 cm(-1) that shifts to 1617 cm(-1) in 12 min with most of the shift occurring in 10 s.
authors.affiliation: Stockholm University, Department of Biochemistry and Biophysics, Arrhenius Laboratories, 10691 Stockholm, Sweden.
authors.forename: Paulami
authors.initials: P
authors.lastname: Mandal
authors.forename: Nadejda
authors.initials: N
authors.lastname: Eremina
authors.forename: Andreas
authors.initials: A
authors.lastname: Barth
mesh_terms: D016229:Amyloid beta-Peptides / Q000737:chemistry* / Q000378:metabolism; D002942:Circular Dichroism; D006863:Hydrogen-Ion Concentration; D009578:Nitrobenzenes / Q000737:chemistry; D010446:Peptide Fragments / Q000737:chemistry* / Q000378:metabolism; D010782:Photolysis; D017433:Protein Structure, Secondary; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: C473956:1-(2-nitrophenyl)ethyl sulfate; D016229:Amyloid beta-Peptides; D009578:Nitrobenzenes; D010446:Peptide Fragments; C092395:amyloid beta-protein (12-28)