Insulin conformational changes under high pressure in structural studies and molecular dynamics simulations

To study the mechanisms underlying protein misfolding and aggregation, therapeutic proteins can be successfully used as a model. Currently, insulin is widely tested as a useful model in this field, since it has been proved in both in vivo and in vitro studies that this small protein aggregates. In this article, exploiting the optimal coupling between high pressure protein crystallography and dynamic simulations, we probe the insulin conformations observed under high pressure, namely over the ranges 0-200 MPa for crystallographic experiments and 0-500 MPa for simulations. Crystal structures of insulin determined with diamond anvil cell technique present a step forward in understanding how pressure can modify protein conformation. Obtained results show different responses to volume compression of different fragments of the insulin molecule. For the first time, we have structurally proved that pressure noticeably modifies fragments of insulin molecules, especially terminal fragments of chain B. The observed structural modifications of insulin molecule in crystal state under pressure were compared to the results of insulin pressurization investigated by the molecular dynamic simulations. Comparing the crystallographic results and MD simulations, we were able to draw important considerations about the role of specific amino acids in pressure-induced insulin conformations. (C) 2019 Elsevier B.V. All rights reserved.