Molecular aspect of drug transport and metabolism by brain carboxylesterases in rats and humans

羧酸酯酶（CES，E.C.3.1.1.1）在多种内源性和外源性化合物的水解中发挥作用，并在许多哺乳动物物种的药物和脂质代谢中发挥重要作用。这种酶也是某些致癌物质代谢活化的途径。我们已经报道了人脑CES制剂与人抗肝CES抗体具有免疫交叉反应性，并且通过免疫印迹分析在胞质组分中检测到脑CES，而不是在微粒体组分中。通过免疫组织化学方法和使用抗人肝CES抗体已经确定了CES特异性存在于人脑内皮细胞中，表明中枢神经系统和肝脏中存在类似的同工酶。脑毛细血管内皮细胞作为一个动态界面，将营养物质和药物从循环系统转移到脑间质液中。毛细血管内皮细胞中CESs的存在 ...更多信息 LLS与保护中枢神经系统免受有毒酯的作用的酶一致，并且可能是所谓的血脑屏障系统的组分。本研究以人肝细胞色素ESHU 1为探针，利用噬斑杂交技术筛选人脑细胞色素ESHU 11文库。分离几个克隆并测序。该克隆的3 '端核苷酸序列包括一个以终止密码子（TAG）终止的开放阅读区、一个含有多聚腺苷酸化信号（AATAAA）的非翻译区和poly（A）尾。该克隆推导的氨基酸序列具有许多在大鼠、小鼠、狗和人肝CES同工酶中高度保守的结构特征，包括活性位点序列（GESAGG、NKQEXG、GDHXD）和四个可能参与特异性二硫键的半胱氨酸。四个半胱氨酸可能参与特定的二硫键。众所周知，保留在内质网（ER）腔中的蛋白质在其四肽（HXEL代表CES）的羧基末端含有保留信号。然而，人脑CES不包含BR保留信号。综上所述，我们从人脑文库中克隆了一种新的CES同工酶，该同工酶在毛细血管内皮细胞中的存在可能影响酯和酰胺键药物的脑分布。少

Carboxylesterases (CES, E.C.3.1.1.1) function in the hydrolysis of a wide variety of endogenous and xenobiotic compounds, and play an important role in drug and lipid metabolism in many mammalian species. This enzyme also serves as a route of metabolic activation of some carcinogens. We have already reported that a human brain CES preparations was immunocross-reactive with a human anti-liver CES antibody, and that the brain CES was detected in cytosolic fractions, and not in microsomal fractions, by immunoblot analysis. The presence of CES specifically in endothelial cells of human brain has been established by immunohistochemistry methods and using an anti-human liver CES antibody, suggesting the presence of similar isozymes in the central nervous system and the liver. Capillary endothelial cells of brain function as a dynamic interface with regard to the transfer of nutrients and drugs from the circulations to brain interstitial fluid. The presence of CESs in capillary endothelial ce … More lls is consistent with the enzyme acting to protect the central nervous system from toxic esters and may be a component of the so-called blood-brain barrier system. In the present study, lambdagt11 library from human brain was screened by plaque hybridization with CES specific probe of human liver CES HU1. Several clones were isolated and sequenced. The nucleotide sequence of 3'-end of the clone included an open reading flame terminating with stop codon (TAG), followed by untranslated region that included a polyadenylation signal (AATAAA), and poly (A) tail. This deduced amino acid sequence of the clone possessed many structural characteristics that are highly conserved among rat, mouse, dog and human liver CES isozymes, including active site sequence (GESAGG, NKQEXG, GDHXD), and four cysteines which may be involved in the specific disulfide bond., four cysteines which may be involved in the specific disulfide bond. It is well known that proteins which are retained in the endoplasmic reticulum (ER) lumen contain the retention signal at their carboxy- terminal of the tetrapeptide (HXEL for CES). However, the human brain CES was not contained an BR-retention signal. In conclusion, we have cloned a novel CES isozyme from human brain library, which CES present in capillary endothelial cells may influence the cerebral distribution of drugs with ester and amide linkage. Less