Amyloid formation of bovine insulin is retarded in moderately acidic pH and by addition of short-chain alcohols
Journal article, 2020

Protein aggregation and amyloid formation are associated with multiple human diseases, but are also a problem in protein production. Understanding how aggregation can be modulated is therefore of importance in both medical and industrial contexts. We have used bovine insulin as a model protein to explore how amyloid formation is affected by buffer pH and by the addition of short-chain alcohols. We find that bovine insulin forms amyloid fibrils, albeit with different rates and resulting fibril morphologies, across a wide pH range (2-7). At pH 4.0, bovine insulin displayed relatively low aggregation propensity in combination with high solubility; this condition was therefore chosen as basis for further exploration of how bovine insulin's native state can be stabilized in the presence of short-chain alcohols that are relevant because of their common use as eluents in industrial-scale chromatography purification. We found that ethanol and isopropanol are efficient modulators of bovine insulin aggregation, providing a three to four times retardation of the aggregation kinetics at 30-35% (vol/vol) concentration; we attribute this to the formation of oligomers, which we detected by AFM. We discuss this effect in terms of reduced solvent polarity and show, by circular dichroism recordings, that a concomitant change in alpha-helical packing of the insulin monomer occurs in ethanol. Our results extend current knowledge of how insulin aggregates, and may, although bovine insulin serves as a simplistic model, provide insights into how buffers and additives can be fine-tuned in industrial production of proteins in general and pharmaceutical insulin in particular.

Kinetics

Amyloid

Aggregation

Circular dichroism

Insulin

Thioflavin-T

Author

David Bernson

Chalmers, Biology and Biological Engineering, Chemical Biology

Almedina Basic

Chalmers, Biology and Biological Engineering, Chemical Biology

MD Tuhin Abed

Chalmers, Biology and Biological Engineering, Chemical Biology

Fredrik Lime

Nouyron Pulp & Performance Chem AB

Per Jageland

Nouyron Pulp & Performance Chem AB

Magnus Palmlof

Nouyron Pulp & Performance Chem AB

Elin Esbjörner Winters

Chalmers, Biology and Biological Engineering, Chemical Biology

European Biophysics Journal

0175-7571 (ISSN) 1432-1017 (eISSN)

Vol. 49 2 145-153

Subject Categories

Biochemistry and Molecular Biology

Biophysics

Other Industrial Biotechnology

DOI

10.1007/s00249-019-01420-0

PubMed

31901953

More information

Latest update

9/28/2020