Study of protein aggregates

Physical Methods and Models for the Study of Protein Aggregation... 

Lefevre, T., Arseneault, K. and Pezolet, M. (2004). Study of protein aggregation using two-dimensional correlation infrared spectroscopy and spectral simulations. Biopolymers 73 705-715. 

After rehydration, the spectra of both samples are very native-like, indicating that the majority of nonnative molecules have refolded (Figure 3). However, in the spectrum of the sample lyophilized without sucrose, the appearance of a new band near 1625 cm", which is assignable to intermolecular j6-sheet structure, and the decreased intensities in vibrational bands ascribed to a-helix (1656 cm" ) and turn (1688-1665 cm" ) structures, indicate the formation of protein aggregates upon rehydration (see [11] for a detailed review of the study of protein aggregation with infrared spectroscopy). In this sample, 18% of the protein formed insoluble aggregates. In contrast, in the sample lyophilized with sucrose, only 9% insoluble aggregate was noted after rehydration. This reduction in... 

A review by Dong et al. [3.57] provides an overview of how Fourier transform JR spectroscopy can be used to study protein stabilization and to prevent lyophilization- induced protein aggregation. An introduction to the study of protein secondary structures and the processing and interpretation of protein IR spectra is given. 

Immunogenicity may be affected by the route of administration. Extravascular injection has been shown to stimulate antibody formation more than IV application, but this is most likely due to the increased immunogenicity of protein aggregates and precipitates formed at the injection site [44]. A recent study investigated the effect of the route of administration of INF-P preparations on inducing anti-INF-P antibodies in multiple sclerosis patients. The results indicate that IM injections appear less immunogenic compared to SC injections, resulting in both a lower serum level of anti-INF-P antibodies as well as a delay in their appearance [45]. 

In this study a Perkin-Elmer DSC-2 was used and the effect of pH and NaCl concentration on the two protein systems was studied. Calorimetric studies of proteins make it possible to distinguish between the aggregation and denaturation involved in the structure formation of proteins. The effects of aggregation are considered negligible for the qualitative interpretation of DSC thermograms. 

An interesting recent development is the use of arginine-glutamate salt (typically 50 mmol l-1 L-arginine + 50 mmol l-1 L-glutamate) for NMR studies of proteins using CC probes. This zwitterionic salt not only has much lower conductivity than NaCl but has also been shown to help solubilize proteins that are prone to aggregation.9,10... 

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