Two-dimensional Fourier transform infrared FT-IR was applied for the examination of the H/D exchange process in D<sub>2</sub>O solutions of bovine α-lactalbumin. The slow spontaneous H/D exchange at 25 °C was compared with pressure-enhanced and temperature-enhanced H/D exchange. The H/D-exchange process, which takes 48 h at 25 °C and under atmospheric pressure, is completed within 3 h when pressure is gradually elevated up to 180 MPa, or when temperature is increased up to 42.5 °C. Although the slow room-temperature H/D exchange and the fast pressure or temperature-enhanced H/D exchange feature a high degree of similarity between the corresponding second-derivative spectra, the two-dimensional (2D) FT-IR correlation maps revealed that upon the heat treatment the order in which the H/D exchange takes place in the structural domains of α-lactalbumin is altered. It has been observed that these differences can be explained in light of the known properties of α-lactalbumin and the crystallographic data.
Wojciech Dzwolak, Minoru Kato, Akio Shimizu, and Yoshihiro Taniguchi, "Comparative Two-Dimensional Fourier Transform Infrared Correlation Spectroscopic Study on the Spontaneous, Pressure-, and Temperature-Enhanced H/D Exchange in α-Lactalbumin," Appl. Spectrosc. 54, 963-967 (2000)