The zinc form of carnosine dipeptidase 2 (CN2) has dipeptidase activity but its substrate specificity is different from that of the manganese form
The zinc form of carnosine dipeptidase 2 (CN2) has dipeptidase activity but its substrate specificity is different from that of the manganese form
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DOI：
10.1016/j.bbrc.2017.10.100
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发表时间：
2017-12-16
影响因子：
3.1
通讯作者：
Takao, Toshifumi
中科院分区：
文献类型：
--
作者：
Okumura, Nobuaki;Takao, Toshifumi
肌肽二肽酶 II (CN2) 是一种存在于各种脊椎动物组织细胞质中的金属肽酶，在 Mn2+ 存在下催化肌肽和其他几种二肽的水解。尽管小鼠 CN2 的金属结合中心也能够在体外与 Zn2+ 结合，但尚不清楚 CN2 的锌形式是否具有任何酶活性。在本研究中，我们证明 Zn2+ 与 CN2 的结合亲和力比 Mn2+ 更高，正如天然质谱法所证明的那样。还使用各种二肽作为底物检查了CN2的锌形式是否具有酶活性的问题。研究结果表明，CN2 的锌形式可以催化多种不同二肽的水解，包括 Leu-His、Met-His 和 Ala-His，其反应速率与其锰形式相当。另一方面，CN2 的锌形式不催化肌肽和其他几种被 CN2 的锰形式水解的二肽的水解。还在表达 CN2 的 HEK293T 细胞中检查了底物特异性，结果表明 Leu-His、Met-His 在细胞培养物中被水解，但肌肽未被水解。这些结果表明 CN2 的锌形式是一种活性酶，但具有与锰形式不同的底物特异性。 (C) 2017 Elsevier Inc. 保留所有权利。
Carnosine dipeptidase II (CN2), a metallopeptidase present in the cytosol of various vertebrate tissues, catalyzes the hydrolysis of carnosine and several other dipeptides in the presence of Mn2+. Although the metal-binding center of mouse CN2 is also able to associate with Zn2+ in vitro, it was not known whether the zinc form of CN2 has any enzymatic activity. In the present study, we show that Zn2+ has a higher affinity for binding to CN2 than Mn2+, as evidenced by native mass spectrometry. The issue of whether the zinc form of CN2 has enzymatic activity was also examined using various dipeptides as substrates. The findings indicate that the zinc form of CN2 catalyzes the hydrolysis of several different dipeptides including Leu-His, Met-His and Ala-His at a reaction rate comparable to that for its manganese form. On the other hand, the zinc form of CN2 did not catalyze the hydrolysis of carnosine and several other di peptides that are hydrolyzed by the manganese form of CN2. Substrate specificity was also examined in HEK293T cells expressing CN2, and the findings indicate that Leu-His, Met-His, but not carnosine, were hydrolyzed in the cell culture. These results suggest that the zinc form of CN2 is an active enzyme, but with a different substrate specificity from that of the manganese form. (C) 2017 Elsevier Inc. All rights reserved.