Pressure tuning of insulin aggregation pathways

Abstract

The protein aggregation phenomenon is associated with several neurodegenerative diseases and causes inefficient protein expression in vitro. Insulin, an important protein from the medical and pharmaceutical point of view, has been employed as a model to study pressure effects on the aggregation pathways and possible biotechnological implementations. The high-pressure approach to studying mechanisms of aggregation may be beneficial, as pressure, unlike temperature affects exclusively volume of a system. High pressure not only fails to induce aggregation-prone intermediate states in insulin, but also completely prevents the aggregation. Apparently, this is a consequence of the fact that pressure disfavors thermal unfolding, which is a prerequisite of the insulin aggregation. On the other hand, high-pressure promotes aggregation through an alternative and less effective ‘low-volume’ pathway. Although 1 kbar is sufficient to trigger such perturbations during the aggregation, the once-formed aggregates are pressure-insensitive. The 10 kbar-treatment of insulin amyloid results only in minor infrared spectral changes, which are reversible and likely to reflect elastic changes in hydrogen bonding and pressure-forced hydration of the polypeptide backbone.

Keywords:

• Insulin
• Pressure
• Protein hydration
• Aggregation
• Amyloid
• Intermediates

Acknowledgement

W.D. acknowledges support of this work from the Ministry of Science and Information Technology (77/E-72/SPUB-M/5PR UE).