Formation of Two Different Types of Oligomers in the Early Phase of pH-Induced Aggregation of the Alzheimer A尾(12-28) Peptide

详细信息    查看全文

• 作者：Paulami Mandal ; Nadejda Eremina ; Andreas Barth
• 刊名：The Journal of Physical Chemistry B
• 出版年：2012
• 出版时间：October 18, 2012
• 年：2012
• 卷：116
• 期：41
• 页码：12389-12397
• 全文大小：471K
• 年卷期：v.116,no.41(October 18, 2012)
• ISSN：1520-5207

文摘

The early phase in the aggregation process of the Alzheimer鈥檚 peptide A尾(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尾(12-28) peptide. One type has small and/or twisted 尾 sheets with a 尾-sheet band at 1627 cm^鈥?. They form fast (within 60 ms), presumably from initial aggregates, and their spectral signature is consistent with a 尾-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 尾 sheets are antiparallel, planar, and large and show an absorption band at 1622 cm^鈥? that shifts to 1617 cm^鈥? in 12 min with most of the shift occurring in 10 s.