Isobe Kimiyasu, Kitagawa Asuka, Kanamori Kazuma, Kashiwagi Nozomi, Matsui Daisuke, Yamaguchi Takuya, Fuhshuku Ken-Ichi, Semba Hisashi, Asano Yasuhisa
a Biotechnology Research Center andDepartment of Biotechnology , Toyama Prefectural University, Kurokawa , Imizu , Toyama , Japan.
b Asano Active Enzyme Molecule Project , ERATO, JST, Kurokawa , Imizu , Toyama , Japan.
Biosci Biotechnol Biochem. 2018 Oct;82(10):1760-1769. doi: 10.1080/09168451.2018.1490171. Epub 2018 Jul 5.
The leaves of Nandina domestica Thunb. exhibited high hydroxynitrile lyase (HNL) activity in (R)-mandelonitrile synthesis. The specific activity of young leaves was significantly higher than that of mature leaves. We isolated two HNLs with molecular mass of 24.9 kDa (NdHNL-S) and 28.0 kDa (NdHNL-L) from the young leaves. Both NdHNLs were composed of two identical subunits, without FAD and carbohydrates. We purified NdHNL-L and revealed its enzymatic properties. The whole deduced amino acid sequence of NdHNL-L was not homologous to any other HNLs, and the specific activity for mandelonitrile synthesis by NdHNL-L was higher than that by other plant HNLs. The enzyme catalyzed enantioselective synthesis of (R)-cyanohydrins, exhibited high activity at pH 4.0, and high stability in the pH range of 3.5-8.0 and below 55°C. Thus, NdHNL-L is a novel HNL with novel amino acid sequence and has a potential for the efficient production of (R)-cyanohydrins.
南天竹的叶子在（R）-扁桃腈合成中表现出高羟基腈裂解酶（HNL）活性。幼叶的比活性显著高于成熟叶。我们从幼叶中分离出两种分子量分别为24.9 kDa（NdHNL-S）和28.0 kDa（NdHNL-L）的HNL。两种NdHNL均由两个相同的亚基组成，不含FAD和碳水化合物。我们纯化了NdHNL-L并揭示了其酶学性质。NdHNL-L的完整推导氨基酸序列与其他任何HNL均无同源性，且NdHNL-L催化扁桃腈合成的比活性高于其他植物HNL。该酶催化（R）-氰醇的对映选择性合成，在pH 4.0时表现出高活性，在3.5-8.0的pH范围内以及55°C以下具有高稳定性。因此，NdHNL-L是一种具有新氨基酸序列的新型HNL，具有高效生产（R）-氰醇的潜力。
