[Study of the insoluble remainder of human gallstones by scanning electron microscope and Fourier transform infrared spectrum].

The insoluble remainder of brown pigment and mixed gallstones which were dissolved with chloroform, ethanol, ether, and hydrochloric acid were studied by Fourier transform infrared (FT-IR) spectrum and scanning electron microscope. It was found that bilirubinate salts, proteins, fatty salts, phosphate and calcium carbonate are the main components in the insoluble remainder of gallstones. The secondary structure of proteins in brown pigment gallstones may be predominated by alpha-helix. The microstructure of proteins in brown pigment stones is membranous, phosphate and bilirubinate salts were trapped within the membranes. The relationship between the insoluble components and formation of gallstones was discussed.