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Abstract：
Phosphatases are hydrolytic enzymes that cleave the phosphoester bond of numerous substrates containing phosphorylated residues. The typical classification divides them into acid or alkaline depending on the pH at which they have optimal activity. The histidine phosphatase (HP) superfamily is a large group of functionally diverse enzymes characterized by having an active-site His residue that becomes phosphorylated during catalysis. HP enzymes are relevant biomolecules due to their current and potential application in medicine and biotechnology. Entamoeba histolytica, the causative agent of human amoebiasis, contains a gene (EHI_146950) that encodes a putative secretory acid phosphatase (EhHAPp49), exhibiting sequence similarity to histidine acid phosphatase (HAP)/phytase enzymes, i.e., branch-2 of HP superfamily. To assess whether it has the potential as a biocatalyst in removing phosphate groups from natural substrates, we studied the EhHAPp49 structural and functional features using a computational-experimental approach. Although the combined outcome of computational analyses confirmed its structural similarity with HP branch-2 proteins, the experimental results showed that the recombinant enzyme (rEhHAPp49) has negligible HAP/phytase activity. Nonetheless, results from supplementary activity evaluations revealed that rEhHAPp49 exhibits Mg2+-dependent alkaline pyrophosphatase activity. To our knowledge, this study represents the first computational-experimental characterization of EhHAPp49, which offers further insights into the structure-function relationship and the basis for future research.
摘要：
磷酸酶是裂解许多含有磷酸化残基的底物的磷酸酯键的水解酶。典型的分类根据它们具有最佳活性的pH将它们分为酸性或碱性。组氨酸磷酸酶（HP）超家族是一大组功能多样的酶，其特征在于具有在催化过程中被磷酸化的活性位点His残基。HP酶是相关的生物分子，因为它们在医学和生物技术中的当前和潜在应用。溶组织内阿米巴,人类阿米巴病的病原体，包含一个基因（EHI_146950），该基因编码推定的分泌酸性磷酸酶（EhHAPp49），表现出与组氨酸酸性磷酸酶（HAP）/植酸酶的序列相似性，即，HP超家族的分支-2。为了评估它是否具有作为生物催化剂从天然底物中去除磷酸基团的潜力，我们使用计算实验方法研究了EhHAPp49的结构和功能特征。尽管计算分析的综合结果证实了其与HP分支2蛋白的结构相似性，实验结果表明，重组酶（rEhHAPp49）的HAP/植酸酶活性可忽略不计。尽管如此，补充活性评估的结果表明，rEhHAPp49表现出依赖Mg2的碱性焦磷酸酶活性。据我们所知,这项研究代表了EhHAPp49的首次计算实验表征，它提供了对结构-功能关系的进一步见解和未来研究的基础。
