Pressure-tuning the conformation of bovine pancreatic trypsin inhibitor studied by Fourier-transform infrared spectroscopy

Abstract

A hydrostatic pressure of 1.5 GPa induces changes in the secondary structure of bovine pancreatic tryspin inhibitor (BPTI) as revealed by the analysis of the amide I' band with Fourier-transform infrared (FTIR) spectroscopy in the diamond anvil cell. The features of the secondary structure remain distinct at high pressure suggesting that the protein does not unfold. The fitted percentages of the secondary structure elements during compression and decompression strongly suggest that the pressure-induced changes are reversible. The pressure-induced changes in the tyrosine side chain band are also reversible. The results demonstrate that the infrared technique explores different aspects of the behaviour of proteins in comparison with two published molecular dynamics studies performed up to 1 GPa [Kitchen, D. B., Reed, L. H. and Levy, R. M. (1992) Biochemistry 32, 10083-10093] and 509 MPa [Brunne, R. M. and van Gunsteren, W. E (1993) FEES Lett. 323, 215-217]. A possible explanation for the difference is the time scale of the experiments.