Structural requirement of monophosphates for inhibition of Na+-Pi cotransport in renal brush border membrane.
Structural requirement of monophosphates for inhibition of Na+-Pi cotransport in renal brush border membrane.
复制标题
单磷酸盐抑制肾刷状缘膜 Na-Pi 共转运的结构要求。
DOI：
10.1016/0006-2952(89)90514-5
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发表时间：
1989
影响因子：
5.8
通讯作者：
Dousa,TP
中科院分区：
文献类型：
--
作者：
Szczepanska-Konkel,M;Yusufi,AN;Lin,JT;Dousa,TP
使用膦酰基乙酸（PAA）和相关的膦酸酯化合物的化学结构类似物，我们调查的结构特征所需的竞争性抑制Na+-Picotransfer在大鼠肾皮质刷状缘膜（BBM）囊泡（BBMV）。在转运测定培养基中使用不同的底物与~（32）Pi浓度比来检查化合物对BBMV的[Na+0>Nai+]-梯度依赖性~（32）Pi摄取的影响。用胂基取代PAA中的膦酰基，或用氨基或羟基取代PAA中的羧基，完全消除了对Na+-Picotransfer的抑制作用。PAA与肼或羟胺偶联后，羧基的电负性降低，抑制效果降低。在PAA的α-碳上用乙基或对氯苯基取代H，抑制活性完全消失，而α-卤代溴则使PAA的抑制活性大大提高，接近膦甲酸（PFA）的抑制活性。所有活性测试的单磷酸盐的抑制是严格竞争的。在100 mM NaCl存在下，测试化合物置换预结合到BBMV上的[14 C]PFA。单磷酸盐抑制Na+-Picotransfer的能力与[14 C]PFA的结合密切相关（r= 0.925; P < 0.001）。这些结果表明：（a）PAA分子两端的电负性较强，（B）α-碳上的α-脂肪族或芳香族取代基可能阻碍抑制剂进入BBM中Na+-Picotransporter的Pi结合位点，（c）α-亲电取代基Br-增强PAA的抑制作用。测试的化合物抑制Na+-Picotransfer通过结合，在Na+的存在下，在相同的网站上的管腔表面的BBM的PFA，并通过扩展，Pi。
Using the chemical structural analogs of phosphonoacetic acid (PAA) and related phosphonate compounds, we investigated which structural features are required for competitive inhibition of Na+-Picotransport in rat renal cortical brush border membrane (BBM) vesicles (BBMV). The effects of compounds on [Na+0>Nai+]-gradient-dependent32Piuptake by BBMV were examined using various inhibitor-to-32Piconcentration ratios in the transport assay medium. The replacement of a phosphono-group with an arsono-group in PAA, or the substitution of a carboxylic group in PAA by an amino or hydroxyl group, totally abolished the inhibitory action on Na+-Picotransport. Decreased electro-negativity of carboxyl in PAA by coupling with hydrazine or hydroxylamine lowered the inhibitory potenty of PAA. Substitution of H at the α-carbon of PAA with ethyl orp-Cl-phenyl groups completely abolished the inhibitory activity, whereas α-halogenation with Br greatly increased the inhibitory potency of PAA, close to that of phosphonoformic acid (PFA). The inhibition by all the active tested monophosphates was strictly competitive. The tested compounds displaced [14C]PFA pre-bound onto BBMV in the presence of 100 mM NaCl. The ability of monophosphates to inhibit Na+-Picotransport across BBM and the binding of [14C]PFA were closely correlated (r= 0.925; P < 0.001). These results show that: (a) strong electronegativity at both ends of the PAA molecule is needed for inhibitory action, (b) an α-aliphatic or aromatic substituent at the α-carbon probably hinders the acess of the inhibitor to the Pi-binding site of the Na+-Picotransporter in BBM, whereas (c) an α-electrophilic substituent—Br—enhances the inhibitory potency of PAA. The tested compounds inhibited Na+-Picotransport by binding, in the presence of Na+, on the same site on the luminal surface of BBM as did PFA and, by extension, Pi.