Electrophoretic separation and characterization of urinary glycosaminoglycans and their roles in urolithiasis.
Urinary polyanions recovered from the urine samples of kidney stone-formers and normal controls were subjected to preparative agarose gel electrophoresis, which yielded fractions 1-5 in a decreasing order of mobility. In both groups, chondroitin sulfates were identified in the fast-moving fractions and heparan sulfates in the slow-moving fractions. Furthermore, two types of heparan sulfates were identified based on their electrophoretic mobility: slow-moving and fast-moving. The fractionated urinary polyanions were then tested in an in vitro calcium oxalate crystallization assay and compared at the same uronic acid concentration, whereby, the chondroitin sulfates of stone-formers and heparan sulfates of normals enhanced crystal nucleation. Fraction 5 of the normals, containing glycoproteins (14-97 kDa) and associated glycosaminoglycans, were found to effectively inhibit crystallization. Papainization of this fraction in stone-formers revealed crystal-suppressive effects of glycoproteins, which was not seen in similar fractions of normals. It was concluded that glycoproteins could modulate the crystal-enhancing glycosaminoglycans such as chondroitin sulfates of stone-formers but not in normals. The differing crystallization activities of electrophoretic fraction 1 of normals and stone-formers revealed the presence of another class of glycosaminoglycan-hyaluronan. Hence, in the natural milieu, different macromolecules combine to have an overall outcome in the crystallization of calcium oxalate.
Gohel
Mayur Danny I
MD
Department of Health Technology and Informatics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China. danny.gohel@polyu.edu.hk <danny.gohel@polyu.edu.hk>
Shum
Daisy K Y
DK
Tam
Po Chor
PC
D000328:Adult; D002129:Calcium Oxalate / Q000302:isolation & purification / Q000652:urine*; D002809:Chondroitin Sulfates / Q000302:isolation & purification / Q000652:urine*; D003460:Crystallization; D004587:Electrophoresis, Agar Gel; D004588:Electrophoresis, Cellulose Acetate; D006023:Glycoproteins / Q000378:metabolism; D006497:Heparan Sulfate / Q000302:isolation & purification / Q000652:urine*; D006801:Humans; D007669:Kidney Calculi; D008875:Middle Aged; D014545:Urinary Calculi / Q000652:urine*; D052878:Urolithiasis
D002129:Calcium Oxalate; D002809:Chondroitin Sulfates; D006023:Glycoproteins; D006497:Heparan Sulfate