Rusconi Stefano, Innocenti Alessio, Vullo Daniela, Mastrolorenzo Antonio, Scozzafava Andrea, Supuran Claudiu T
Istituto di Malattie Infettive e Tropicali, Università degli Studi di Milano, Ospedale Luigi Sacco, via G.B. Grassi 74, 20157 Milano, Italy.
Bioorg Med Chem Lett. 2004 Dec 6;14(23):5763-7. doi: 10.1016/j.bmcl.2004.09.064.
A detailed inhibition study of five carbonic anhydrase (CA, EC 4.2.1.1) isozymes with inorganic phosphates, carbamoyl phosphate, the antiviral phosphonate foscarnet as well as formate is reported. The cytosolic isozyme hCA I was weakly inhibited by neutral phosphate, strongly inhibited by carbamoyl phosphate (K(I) of 9.4 microM), and activated by hydrogen- and dihydrogenphosphate, foscarnet and formate (best activator foscarnet, K(A)=12 microM). The cytosolic isozyme hCA II was weakly inhibited by all the investigated anions, with carbamoyl phosphate showing a K(I) of 0.31 mM. The membrane-associated isozyme hCA IV was the most sensitive to inhibition by phosphates/phosphonates, showing a K(I) of 84 nM for PO(4)(3-), of 9.8 microM for HPO(4)(2-), and of 9.9 microM for carbamoyl phosphate. Foscarnet was the best inhibitor of this isozyme (K(I) of 0.82 mM) highly abundant in the kidneys, which may explain some of the renal side effects of the drug. The mitochondrial isozyme hCA V was weakly inhibited by all phosphates/phosphonates, except carbamoyl phosphate, which showed a K(I) of 8.5 microM. Thus, CA V cannot be the isozyme involved in the carbamoyl phosphate synthetase I biosynthetic reaction, as hypothesized earlier. Furthermore, the relative resistance of CA V to inhibition by inorganic phosphates suggests an evolutionary adaptation of this mitochondrial isozyme to the presence of high concentrations of such anions in these energy-converting organelles, where high amounts of ATP are produced by ATP synthetase, from ADP and inorganic phosphates. The transmembrane, tumor-associated isozyme hCA IX was on the other hand slightly inhibited by all these anions.
报道了无机磷酸盐、氨基甲酰磷酸、抗病毒膦甲酸酯以及甲酸对五种碳酸酐酶（CA，EC 4.2.1.1）同工酶的详细抑制研究。胞质同工酶hCA I受到中性磷酸盐的微弱抑制，被氨基甲酰磷酸强烈抑制（抑制常数K(I)为9.4 microM），并被磷酸一氢根、磷酸二氢根、膦甲酸酯和甲酸激活（最佳激活剂为膦甲酸酯，激活常数K(A)=12 microM）。胞质同工酶hCA II受到所有研究阴离子的微弱抑制，氨基甲酰磷酸的抑制常数K(I)为0.31 mM。膜相关同工酶hCA IV对磷酸盐/膦酸酯的抑制最为敏感，对磷酸根离子PO(4)(3-)的抑制常数K(I)为84 nM，对磷酸氢根离子HPO(4)(2-)的抑制常数K(I)为9.8 microM，对氨基甲酰磷酸的抑制常数K(I)为9.9 microM。膦甲酸酯是该同工酶的最佳抑制剂（抑制常数K(I)为0.82 mM），在肾脏中含量很高，这可能解释了该药物的一些肾脏副作用。线粒体同工酶hCA V受到除氨基甲酰磷酸外所有磷酸盐/膦酸酯的微弱抑制，氨基甲酰磷酸的抑制常数K(I)为8.5 microM。因此，如之前所假设的，CA V不可能是参与氨基甲酰磷酸合成酶I生物合成反应的同工酶。此外，CA V对无机磷酸盐抑制的相对抗性表明，这种线粒体同工酶在这些能量转换细胞器中对高浓度此类阴离子的存在进行了进化适应，在这些细胞器中，ATP合成酶由ADP和无机磷酸盐产生大量ATP。另一方面，跨膜的肿瘤相关同工酶hCA IX受到所有这些阴离子的轻微抑制。
