Thermal techniques in biomembrane and lipoprotein research

Abstract

In structural determinations of inanimate materials, thermal analysis has long proven to be a powerful technique, particularly when coupled with X-ray diffraction or spectroscopic methods. In molecular biology, thermal analysis, frequently combined with other techniques, similarly shows itself to be a powerful tool. Its importance is not limited solely to understanding biological structures but extends to understanding physiological processes as well. This paper describes the application to molecular biology of differential scanning calorimetry (DSC) and the complementary technique of differential scanning dilatometry (DSD). The modification and operation of two commercial differential scanning calorimeters for use in molecular biology is discussed, as well as the design and operation of a novel differential scanning dilatometer together with its auxiliary techniques. Some examples are given of the uses of these methods in understanding the structure, thermodynamic state, and physiological functions of biological membranes. A further illustration of the type of approach taken in applying thermal analysis to molecular biology is provided by a description of an ongoing study. This study uses DSC and DSD in correlation with the temperature dependence of ultraviolet circular dichroism (CD) to elucidate the structures of human high density (HDL) and low density (LDL) serum lipoproteins.