Method provided evidence for structural transitions in fibril-forming peptides.
University of California, Santa Barbara scientists say that they have established the potential of ion-mobility spectrometry/mass spectrometry (IMS/MS) for the study of amyloid diseases like Alzhiemer, Huntington, and Parkinson diseases. They used IMS/MS to find the conversion of randomly assembled aggregates of small peptides into ordered beta sheets that comprise fibrils.
Details of the method and study results appear in Nature Chemistry. The paper is titled “Ion mobility-mass spectrometry reveals a conformational conversion from random assembly to β-sheet in amyloid fibril formation.”
Amyloid cascades that lead to peptide β-sheet fibrils and plaques are central to many important diseases. Recently, intermediate assemblies of these cascades were identified as the toxic agents that interact with cellular machinery, according to Michael T. Bowers, Ph.D., lead author and professor in the department of chemistry and biochemistry.
The location and cause of the transformation from a natively unstructured assembly to the β-sheet oligomers found in all fibrils is important in understanding disease onset and the development of therapeutic agents. Largely, research on this early oligomeric region was unsuccessful because all the traditional techniques measure only the average oligomer properties of the ensemble, Dr. Bowers points out.
He describes how understanding the fundamental forces that relate aggregation, shape, and biochemistry of soluble peptide aggregates is central to developing diagnostic and therapeutic strategies for amyloid diseases. The team utilized ion-mobility methods to deduce the peptide self-assembly mechanism. They examined a series of amyloid-forming peptides clipped from larger peptides or proteins associated with disease.
The scientists note that their research provides evidence for structural transitions in each of these fibril-forming peptide systems. Dr. Bowers says that IMS-MS has the potential to open new avenues for investigating the pathogenic mechanisms of amyloid diseases, their early diagnosis, and eventual treatment.