Kalaiselvi P, Selvam R
Department of Medical Biochemistry, Dr Alm PG Institute of Basic Medical Sciences, University of Madras, Taramani, Chennai, India.
BJU Int. 2001 Jan;87(1):110-6. doi: 10.1046/j.1464-410x.2001.00972.x.
To determine the functional role of calcium oxalate binding proteins in the nucleation, aggregation and retention of calcium oxalate crystals under physiological and hyperoxaluric conditions. Materials and methods Hyperoxaluria was induced in rats using 0.75% of ethylene glycol in drinking water. Calcium oxalate binding proteins were isolated and fractionated by cellulose column chromatography. Three major protein peak fractions were obtained (73 kDa in Tris-HCl buffer, 20 kDa in 0.05 mol/L NaCl buffer and 23 kDa in 0.3 mol/L buffer). Oxalate binding and the inhibition of crystal nucleation and aggregation by these fractions were determined.
The adsorption of calcium oxalate monohydrate (COM) was ubiquitous in rat tissues and subcellular organelles, but the percentage adsorption varied; maximum absorption occurred in kidneys and pancreas, with microsomes showing maximal adsorption in the kidney. Hyperoxaluric rat tissues showed a greater percentage adsorption. Microsomes were enriched with the 20 kDa protein, while nuclei contained the 23 kDa protein in higher concentrations. COM-binding proteins derived from hyperoxaluric rat kidney had a greater content of 74 kDa and 23 kDa proteins with increased oxalate-binding activities. In the crystal-growth studies, the 74 kDa protein was a promoter, while the other protein fractions inhibited crystallization. In hyperoxaluria, the crystal-growth promoting activity of the 74 kDa protein was further increased, while the inhibition by the 20 and 23 kDa proteins was decreased. The 74 kDa protein derived from control rats formed single COM crystals in a crystal growth system, while the hyperoxaluric rat fraction induced the aggregation of COM crystals.
COM-binding proteins (the 74 and 23 kDa fractions) were expressed more in hyperoxaluric rats. In hyperoxaluria the 74 kDa protein tended to promote crystal nucleation and aggregation, and the 20 and 23 kDa proteins were less inhibitory, which increases the risk of stone formation.
确定草酸钙结合蛋白在生理和高草酸尿条件下对草酸钙晶体成核、聚集和潴留的功能作用。材料与方法 用饮用水中0.75%的乙二醇诱导大鼠产生高草酸尿。通过纤维素柱色谱法分离和分级草酸钙结合蛋白。获得了三个主要的蛋白峰级分（在Tris-HCl缓冲液中为73 kDa，在0.05 mol/L NaCl缓冲液中为20 kDa，在0.3 mol/L缓冲液中为23 kDa）。测定了这些级分的草酸结合以及对晶体成核和聚集的抑制作用。
一水合草酸钙（COM）在大鼠组织和亚细胞器中的吸附普遍存在，但吸附百分比有所不同；最大吸附发生在肾脏和胰腺，其中微粒体在肾脏中显示出最大吸附。高草酸尿大鼠组织的吸附百分比更高。微粒体富含20 kDa的蛋白，而细胞核中23 kDa蛋白的浓度更高。来自高草酸尿大鼠肾脏的COM结合蛋白中74 kDa和23 kDa蛋白的含量更高，草酸结合活性增加。在晶体生长研究中，74 kDa蛋白是促进剂，而其他蛋白级分抑制结晶。在高草酸尿症中，74 kDa蛋白的晶体生长促进活性进一步增加，而20 kDa和23 kDa蛋白的抑制作用减弱。来自对照大鼠的74 kDa蛋白在晶体生长系统中形成单个COM晶体，而高草酸尿大鼠的级分诱导COM晶体聚集。
COM结合蛋白（74 kDa和23 kDa级分）在高草酸尿大鼠中表达更多。在高草酸尿症中，74 kDa蛋白倾向于促进晶体成核和聚集，而20 kDa和23 kDa蛋白的抑制作用较弱，这增加了结石形成的风险。
