Influence of Solvent on the Active Site Environment of Lactoperoxidase

描述（由申请人提供）：乳过氧化物酶（LPO）是哺乳动物过氧化物酶家族的一员，在多种分泌液（包括泪液、唾液和宫颈液）中充当第一道防线。虽然乳过氧化物酶在结构上能够将各种小分子结合到其活性位点，但在过氧化氢（H2 O2）存在下，只有硫氰酸盐（SCN-）与LPO相互作用以形成杀生物剂。最近，LPO被鉴定为对诸如葡萄球菌和大肠杆菌的细菌具有抗菌活性。大肠杆菌，而存在于哺乳动物的呼吸分泌物。在囊性纤维化（CF），一种系统性疾病，其特征是不断的肺部感染，炎症和粘蛋白含量增加，这种抗菌系统已被证明功能障碍。这项工作的重点是了解结构的作用，溶剂在乳过氧化物酶的偏好，其配体，并最终如何影响其功能的偏好。具体目标如下：1）使用各种结合的配体来探测LPO的活性位点血红素环境; 2）检查远端精氨酸在有序化水导致LPO的溶剂可及腔中的作用;以及3）表征粘蛋白与乳过氧化物酶分子的相互作用。囊性纤维化（CF）是一种特别具有威胁性的疾病，不仅因为其受影响的人群中有很大一部分是儿童，而且还因为它是一种多系统疾病，使其非常难以研究。在患有CF的人的气道内，乳过氧化物酶，一种负责攻击入侵细菌的酶，已被证明是有缺陷的。这项工作的目标是更准确地了解这种酶是如何工作的，并最终为更有针对性的治疗提供未来的方向。

DESCRIPTION (provided by applicant): A member of the mammalian peroxidase family, lactoperoxidase (LPO) serves as the first line of defense in a variety of secretory fluids including tears, saliva, and cervical fluid. While lactoperoxidase is structurally capable of binding a variety of small molecules to its active site, only thiocyanate (SCN-) interacts with LPO while in the presence of hydrogen peroxide (H2O2) to form a biocidal agent. Recently, LPO was identified as contributing antimicrobial activity against bacteria such as staphylococci and E. coli while present in mammalian respiratory secretions. In cystic fibrosis (CF), a systematic disease characterized by incessant lung infections, inflammation, and increased mucin content, this antimicrobial system has been shown to dysfunction. This work focuses on understanding the structural role that solvent plays in lactoperoxidase's preference for its ligands and ultimately how this preference affects its functionality. The specific aims are as follows: 1) Use various bound ligands to probe the active site heme environment of LPO; 2) Examine the role of distal arginine in ordering water leading to the solvent accessible cavity of LPO; and 3) Characterize the interaction of mucin proteins with lactoperoxidase molecules. Cystic fibrosis (CF) is a particularly menacing disease not only because a large portion of its affected population are children, but also because it is a multi-system disease, making it very difficult to study. Within the airways of those afflicted with CF, lactoperoxidase, an enzyme responsible for attacking invading bacteria, has been shown to be faulty. The goals of this work are to gain a more accurate understanding of how this enzyme works and ultimately provide future directions for more targeted therapies.