Identification of a novel acidic mammalian chitinase distinct from chitotriosidase
Identification of a novel acidic mammalian chitinase distinct from chitotriosidase
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DOI：
10.1074/jbc.m009886200
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发表时间：
2001-03-02
影响因子：
4.8
通讯作者：
Aerts, JMFG
中科院分区：
文献类型：
--
作者：
Boot, RG;Blommaart, EFC;Aerts, JMFG
几丁质酶是一种普遍存在的裂解几丁质的水解酶。最近我们发现了第一个由吞噬细胞特异性表达的人几丁质酶，命名为几丁三糖苷酶。我们在这里报道了第二种哺乳动物几丁质酶的鉴定、纯化和随后的克隆。这种酶的特征是具有酸性等电点，因此被称为酸性哺乳动物几丁质酶(AMCase)。在啮齿动物和人类中，这种酶在胃肠道中相对丰富，在肺中的含量较低。与壳三糖苷酶一样，AMCase被合成为一个50 kDa的蛋白质，含有一个39 kDa的N端催化区、一个铰链区和一个C端的几丁质结合区。与壳三糖酶相比，该酶具有极强的酸性稳定性，在pH 2附近有明显的第二最适pH。AMCase能够裂解人工合成的甲壳素底物以及存在于真菌细胞壁中的蟹壳甲壳素和甲壳素。我们的研究揭示了胃肠道和肺中存在一种几丁质分解酶，它可能在消化和/或防御中发挥作用。
Chitinases are ubiquitous chitin-fragmenting hydro lases. Recently we discovered the first human chitinase, named chitotriosidase, that is specifically expressed by phagocytes. We here report the identification, purification, and subsequent cloning of a second mammalian chitinase. This enzyme is characterized by an acidic isoelectric point and therefore named acidic mammalian chitinase (AMCase). In rodents and man the enzyme is relatively abundant in the gastrointestinal tract and is found to a lesser extent in the lung. Like chitotriosidase, AMCase is synthesized as a 50-kDa protein containing a 39-kDa N-terminal catalytic domain, a hinge region, and a C-terminal chitin-binding domain. In contrast to chitotriosidase, the enzyme is extremely acid stable and shows a distinct second pH optimum around pH 2. AMCase is capable of cleaving artificial chitin-like substrates as well as crab shell chitin and chitin as present in the fungal cell wall. Our study has revealed the existence of a chitinolytic enzyme in the gastrointestinal tract and lung that may play a role in digestion and/or defense.