Ion-Binding Properties of Electrophoretically Homogeneous Mucoproteins of Urine in Normal Subjects and in Patients with Renal Calculus Disease

Publisher Website
Google Scholar
Abstract
A study of the ion-binding properties of mucoproteins was undertaken. The methods of isolation of urinary biocolloids and the analysis are described. It was found that both normal urine and urine from patients with calculous disease contain at least 2 mucoproteins which retain a negative charge throughout the entire pH range of urine. Both of these mucoproteins are markedly increased in the urine of patients with calcigerous renal calculi. One of these mucoproteins, fraction I, is soluble in buffers throughout the pH range of urine. As recovered from calculous disease of urine it has been demonstrated to bind Ca with avidity, forming an insoluble complex. When the incubating solution contains phosphate ions, in addition to Ca, a progressive formation of crystalline calcium phosphate follows the appearance of the Ca-mucoprotein precipitate. The largest single component of the urinary biocolloids in the normal subjects and in patients with calculous disease is a carbohydrate-protein conjugation joined by polymer linkage to form a compound of high molecular weight. On the basis of the carbohydrate content and the electrophoretic and chemical properties, it is suggested that this material may be correctly referred to as uromucoid. The polymerized form is insoluble in molar NaCl or in buffers of pH range 4.5-8.6, but the depolymerized uromucoid is highly soluble in these solutions. In calcifying solutions the depolymerized uromucoid from both normal subjects and from patients with calculous disease has exhibited ion-binding properties similar to those of the fraction I mucoprotein obtained from the urine of patients with calculous disease.