MicroGISAXS of Langmuir-Blodgett protein films: effect of temperature on long-range order

The grazing-incidence small-angle X-ray scattering technique has been used here with a microfocus beamline (microGISAXS) to study the effect of temperature on the protein reorganization taking place in a Langmuir-Schaefer multilayered enzyme film. The study appears quite reproducible in the two enzymes being utilized, penicillin G acylase and urease. In-plane and out-of-plane cuts are used to account for the changes in the film thickness and distance between structures taking place by the process of heating up to 423 K and cooling to room-temperature. The out-of-plane cut suggests that the structures are getting closer and are becoming more organized owing to the heating affect. Merging of layers is likely to occur during the heating and cooling process, leading to a loss of correlation between the interfaces of the layers and to the establishment of long-range order. The dramatic increase in long-range order in the Langmuir-Blodgett multilayered enzyme films after heating and cooling, made here apparent by grazing-incidence small-angle X-ray scattering using a microbeam, could in the future open the way to avoiding the bottleneck of protein crystallization for protein structure determination.