Beil W, Bierbaum S, Sewing K F
Institut für Allgemeine Pharmakologie, Medizinische Hochschule Hannover, FRG.
Pharmacology. 1993 Aug;47(2):141-4. doi: 10.1159/000139089.
The effects of colloidal bismuth subcitrate (CBS) on porcine pepsin have been studied in vitro. CBS inhibited pepsin activity in a pH-dependent manner. CBS was not active at pH 4.0 but inhibited pepsin activity at pH 1.0 (IC50: 2.3 +/- 0.09 mmol/l) and pH 2.0 (IC50: 8.9 +/- 0.7 mmol/l). This inhibition was reversible. In the presence of the sulfhydryl ligand mercaptoethanol, which prevents precipitation of CBS, the inhibitory potency of CBS increased. CBS bound to both positively (Amberlite) and negatively charged (Dowex) ion exchangers in a pH-dependent manner. With increasing acidity, binding to Amberlite increased, whereas binding to Dowex decreased. From these data we conclude that negatively charged bismuth salts derived from CBS bind at pH 2.0 and 1.0 via an ionic interaction to positively charged groups of pepsin, thereby inactivating the enzyme.
已在体外研究了枸橼酸铋钾（CBS）对猪胃蛋白酶的影响。CBS以pH依赖的方式抑制胃蛋白酶活性。CBS在pH 4.0时无活性，但在pH 1.0（IC50：2.3±0.09 mmol/L）和pH 2.0（IC50：8.9±0.7 mmol/L）时抑制胃蛋白酶活性。这种抑制是可逆的。在存在防止CBS沉淀的巯基配体巯基乙醇的情况下，CBS的抑制效力增加。CBS以pH依赖的方式与带正电荷（Amberlite）和带负电荷（Dowex）的离子交换剂结合。随着酸度增加，与Amberlite的结合增加，而与Dowex的结合减少。从这些数据我们得出结论，CBS衍生的带负电荷的铋盐在pH 2.0和1.0时通过离子相互作用与胃蛋白酶的带正电荷基团结合，从而使酶失活。
