This Article Full Text Full Text (PDF) All Versions of this Article: biophysj.107.123133v1 94/8/3241    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Smirnovas, V. Articles by Winter, R. Search for Related Content PubMed PubMed Citation Articles by Smirnovas, V. Articles by Winter, R.

Revealing Different Aggregation Pathways of Amyloidogenic Proteins by Ultrasound Velocimetry

University of Dortmund, Department of Chemistry, Physical Chemistry I, Biophysical Chemistry, Dortmund, Germany

Correspondence: Address reprint requests to Roland Winter, Dept. of Chemistry, Physical Chemistry I, Biophysical Chemistry, University of Dortmund, Otto-Hahn Straße 6, D-44227 Dortmund, Germany. Tel.: 49-231-755-3900; Fax: 49-231-755-3901; E-mail: roland.winter{at}uni-dortmund.de.

In this work, we performed a detailed thermodynamic study, including ultrasound velocimetry, densimetry, calorimetry, and FTIR spectroscopy, of an aggregation-prone protein (insulin) under different salt-screening conditions to gain a deeper insight into the scenario of physicochemical events during its temperature-induced unfolding and aggregation reactions. Differences in aggregation and fibrillization pathways are reflected in changes of the partial molar volume, the coefficients of thermal expansion and compressibility, and the infrared spectral properties of the protein. Combining all experimental data allows setting up a scheme for the temperature-dependent insulin aggregation reaction in the presence and absence of NaCl. As revealed by complementary atomic force microscopy studies, under charge-screening conditions, a process involving structural reorganization, ripening, and formation of more compact nuclei from amorphous oligomers is involved in the formation of mature fibrillar morphologies. In this work, our focus was to put forward a comprehensive discussion of the use of ultrasound velocimetry in disentangling different aggregation pathways. In fact, ultrasound velocimetry proved to be very sensitive to changes in aggregation pathway, highlighting the importance of density and compressibility changes in the different aggregation and fibrillization reactions of the protein.