Crystal growth-inhibiting proteins in bile.

The idea that biliary proteins somehow inhibit nucleation/crystal growth of cholesterol crystals in supersaturated human biles is not new, and some supportive, albeit preliminary, evidence has already been provided for this. Progress in purification of biliary effector proteins has been slow and hindered by the lack of a sensitive and convenient assay method. The formidable problems of removing large amounts of both mucin and lipids from the samples before isolation of biliary proteins has constituted another major obstacle. Recently, the combination of a newly developed nucleation and crystal growth assay and the systematic use of lectin affinity chromatography has enabled rapid progress to be made. With these approaches, glycoprotein fractions containing primarily inhibiting activity and other fractions containing primarily promoting activity have been isolated from normal human biles. Thus these opposing activities can coexist and influence a balance of effects potentially defining the presence of health or disease. The most recent studies have led to the isolation of a single glycoprotein having an extremely potent crystal growth-inhibiting activity.