title: Isolation of calcium oxalate crystal growth inhibitor from rat kidney and urine.
abstract: Glycoproteins that slow the growth rate of calcium oxalate monohydrate crystals were purified from rat kidney homogenate and urine by selective heat denaturation (for rat kidney homogenate), DEAE-cellulose column chromatography, and gel permeation column chromatography. Both kidney and urine inhibitors were glycoproteins with an apparent mol wt of 1.4 X 10(4), as determined by high-performance liquid chromatography. They contained gamma-carboxyglutamic acid and a high percentage of aspartic acid and glutamic acid but had few aromatic amino acid residues. Both inhibitors contained fucose, mannose, glucose, galactose, glucosamine, galactosamine, and N-acetylneuraminic acid but no glucuronic acid. Kinetic studies suggest that purified inhibitors bind to calcium oxalate monohydrate seed crystals according to a Langmuir adsorption isotherm with similar dissociation constants of 14 X 10(-8)M for rat urine inhibitor and 8.7 X 10(-8) M for rat kidney inhibitor. The isolation of similar glycoproteins from kidney and urine suggests that urinary crystal growth inhibitor may be produced in the kidneys.
mesh_terms: D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002129:Calcium Oxalate / Q000037:antagonists & inhibitors* / Q000302:isolation & purification / Q000652:urine; D002848:Chromatography, DEAE-Cellulose; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D006023:Glycoproteins / Q000302:isolation & purification* / Q000652:urine; D007668:Kidney / Q000032:analysis*; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D000596:Amino Acids; D006023:Glycoproteins; C029490:nephrocalcin; D002129:Calcium Oxalate