In Situ Observation of Molecular Steps on the Surface of Protein Crystal under High Pressure

Abstract

Velocities of elementary steps and two-dimensional nucleation rates on the {101} face of glucose isomerase (GI) crystals were measured at pressures of 0.1, 25 and 50 MPa. We conducted in situ observation of the steps by using a laser confocal microscope combined with differential interference contrast microscope (LCM-DIM) and high-pressure vessel with a sapphire window (t = 1 mm). Both step velocities and 2D nucleation rates increased with increasing pressure at T = 26.4°C and C = 5.6 mg ml^-1. Solubilities C_e at high pressures were also measured by in situ observation of the moving steps around equilibrium temperatures. The solubility decreased with increasing pressure.