Formation of Two Different Types of Oligomers in the Early Phase of pH-Induced Aggregation of the Alzheimer A beta(12-28) Peptide
2012 (English)In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 116, no 41, 12389-12397 p.Article in journal (Refereed) Published
The early phase in the aggregation process of the Alzheimer's peptide A beta(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 two different types of aggregates from both versions of the A beta(12-28) peptide. One type has small and/or twisted beta sheets with a beta-sheet band at 1627 cm(-1), They form fast (within 60 ms), presumably from initial aggregates, and their spectral signature is consistent with a beta-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 beta 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.
Place, publisher, year, edition, pages
2012. Vol. 116, no 41, 12389-12397 p.
IdentifiersURN: urn:nbn:se:su:diva-83008DOI: 10.1021/jp305015gISI: 000309902400002OAI: oai:DiVA.org:su-83008DiVA: diva2:574515