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首页> 外文期刊>Biochimica et biophysica acta: BBA: International journal of biochemistry, biophysics and molecular biololgy. Proteins and Proteomics >Structure of bovine lactoperoxidase with a partially linked heme moiety at 1.98 angstrom resolution
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Structure of bovine lactoperoxidase with a partially linked heme moiety at 1.98 angstrom resolution

机译：牛乳酰氧化酶的结构，具有部分连接的血红素部分为1.98埃分辨率

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摘要

Lactoperoxidase (LPO) is a member of mammalian heme peroxidase superfamily whose other members are myeloperoxidase (MPO), eosinophil peroxidase (EPO) and thyroid peroxidase (TPO). In these enzymes, the heme moiety is linked to protein through two or three covalent bonds. In the mature LPO, the heme moiety is linked to protein through two ester bonds with highly conserved glutamate and aspartate residues. The previously reported structures of LPO have confirmed the formation of two covalent linkages involving Glu258 and Asp108 with 1-methyl and 5-methyl groups of pyrrole rings A and C respectively. We report here a new form of structure of LPO where the covalent bond between Glu258 and 1-methyl group of pyrrole ring A is present only in a fraction of protein molecules. In this case, the side chain of Glu258 occupies two distinct positions, each of which has a 0.5 occupancy. In one position, it forms a normal ester covalent linkage while in the second position, the side chain of Glu258 is located in the middle of the substrate binding site on the distal heme side. In this position, the atom of the side chain of Glu258 forms several contacts with atoms of other residues and heme moiety. Out of the two observed positions of the side chain of Glu258, the former contributes to the stabilization of heme position and improved catalytic action of LPO while the latter is responsible for the reduced stability of the heme position as well as it blocks the substrate binding site. (C) 2016 Elsevier B.V. All rights reserved.
机译：乳酰氧基酶（LPO）是哺乳动物血红素过氧化物酶超家族的成员，其其他成员是髓氧化酶（MPO），嗜酸性粒细胞过氧化物酶（EPO）和甲状腺过氧化物酶（TPO）。在这些酶中，血红素部分通过两种或三个共价键与蛋白质连接。在成熟的LPO中，血红素部分通过具有高度保守的谷氨酸和天冬氨酸残基的两种酯键与蛋白质连接。先前报道的LPO结构已经证实了形成涉及Glu258和ASP108的两种共价键，分别具有1-甲基和吡咯环A和C的5-甲基。我们在这里报道了一种新的LPO结构形式，其中Glu258和1-甲基的吡咯环A之间的共价键仅在蛋白质分子的一部分中存在。在这种情况下，Glu258的侧链占据两个不同的位置，每个位置具有0.5个占用。在一个位置，它形成正常的酯共价连杆，同时在第二位置，Glu258的侧链位于远端血红素侧的基底结合位点的中间。在该位置，Glu258的侧链的原子形成与其他残基和血红部分的原子形成几个触点。出于Glu258的侧链的两个观察到的位置，前者有助于血红素位置的稳定，并改善LPO的催化作用，而后者负责降低血红素位置的稳定性以及阻断底物结合位点。 （c）2016年Elsevier B.v.保留所有权利。

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