Hess B
Policlinic of Medicine, University Hospital, Berne, Switzerland.
Miner Electrolyte Metab. 1994;20(6):393-8.
Available data on the effects of Tamm-Horsfall glycoprotein (THP) on calcium oxalate crystallization processes are apparently conflicting. With the main emphasis on calcium oxalate crystal aggregation, this review demonstrates that THP has a dual role as a modifier of crystal aggregation: in solutions with high pH, low ionic strength (IS) and low concentrations of calcium and THP itself, the glycoprotein acts as a powerful inhibitor of calcium oxalate crystal aggregation. Conversely, low pH, high IS and high concentrations of calcium and THP all favor self-aggregation of THP molecules which lowers their inhibitory activity against calcium oxalate crystal aggregation. Some patients with severely recurrent Ca stone disease excrete abnormal THPs which self-aggregate at levels of pH, IS and concentrations of Ca and THP at which normal THPs remain in monomeric form. With high Ca concentrations, such abnormal THPs become strong promoters of crystal aggregation, since conformational changes in crystal-bound THP molecules induce strong viscous binding forces which overcome repulsive electrostatic surface charges. By chelating free Ca ions, citrate reduces self-aggregation of THP molecules and turns promoting THPs into inhibitors of calcium oxalate crystal aggregation.
关于Tamm-Horsfall糖蛋白（THP）对草酸钙结晶过程影响的现有数据明显相互矛盾。本综述主要关注草酸钙晶体聚集，结果表明THP作为晶体聚集的调节剂具有双重作用：在高pH、低离子强度（IS）以及低钙和THP自身浓度的溶液中，该糖蛋白可作为草酸钙晶体聚集的强效抑制剂。相反，低pH、高IS以及高钙和THP浓度均有利于THP分子的自我聚集，从而降低其对草酸钙晶体聚集的抑制活性。一些严重复发性钙结石病患者排泄的异常THP会在正常THP保持单体形式的pH、IS以及钙和THP浓度水平下发生自我聚集。在高钙浓度下，此类异常THP会成为晶体聚集的强效促进剂，因为晶体结合的THP分子构象变化会诱导强大的粘性结合力，从而克服排斥性静电表面电荷。通过螯合游离钙离子，柠檬酸盐可减少THP分子的自我聚集，并将促进性THP转变为草酸钙晶体聚集的抑制剂。
