During malarial infection, Plasmodium parasites digest human hemoglobin to obtain free amino acids for protein production and maintenance of osmotic pressure. The Plasmodium M1 and M17 aminopeptidases are both postulated to have an essential role in the terminal stages of the hemoglobin digestion process and are validated drug targets for the design of new dual-target anti-malarial compounds. In this study, we profiled the substrate specificity fingerprints and kinetic behaviors of M1 and M17 aminopeptidases from Plasmodium falciparum and Plasmodium vivax, and the mouse model species, Plasmodium berghei. We found that although the Plasmodium M1 aminopeptidases share a largely similar, broad specificity at the P1 position, the P. falciparum M1 displays the greatest diversity in specificity and P. berghei M1 showing a preference for charged P1 residues. In contrast, the Plasmodium M17 aminopeptidases share a highly conserved preference for hydrophobic residues at the P1 position. The aminopeptidases also demonstrated intra-peptide sequence specificity, particularly the M1 aminopeptidases, which showed a definitive preference for peptides with fewer negatively charged intrapeptide residues. When tested with a panel of peptides of increasing length, each aminopeptidase exhibited unique catalytic behavioral responses to the increase in peptide length, although all six aminopeptidases exhibited an increase in cooperativity as peptide length increased. Overall the P. vivax and P. berghei enzymes were generally faster than the P. falciparum enzymes, which we postulate is due to subtle differences in structural dynamicity. Together, these results build a kinetic profile that allows us to better understand the catalytic nuances of the M1 and M17 aminopeptidases from different Plasmodium species.

中文翻译：

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绘制疟原虫M1和M17氨肽酶的底物序列和长度图

在疟疾感染期间，疟原虫寄生虫消化人的血红蛋白以获得游离氨基酸，用于蛋白质生产和维持渗透压。疟原虫M1和M17氨基肽酶均被假定在血红蛋白消化过程的终末阶段具有重要作用，并且已被证实是设计新的双靶点抗疟疾化合物的药物靶标。在这项研究中，我们概述了恶性疟原虫和间日疟原虫和小鼠模型物种伯氏疟原虫的M1和M17氨基肽酶的底物特异性指纹和动力学行为。我们发现，尽管疟原虫M1氨基肽酶在P1位置具有极为相似的广泛特异性，但恶性疟原虫M1在特异性和P上显示出最大的多样性。berghei M1显示对带电P1残基的偏爱。相比之下，疟原虫M17氨肽酶对P1位置的疏水残基具有高度保守的偏好。氨基肽酶还表现出肽内序列特异性，特别是M1氨基肽酶，它对具有较少负电荷内肽残基的肽表现出绝对的偏爱。当用一组长度增加的肽测试时，每种氨基肽酶均表现出对肽长度增加的独特催化行为响应，尽管随着肽长度的增加，所有六个氨基肽酶均显示出协同作用的增加。总体而言，间日疟原虫和伯氏疟原虫酶通常比恶性疟原虫酶快，我们推测这是由于结构动力学的细微差异。一起，