Kim Jung-Ho, Kim Junyoung, Kim Hyun-Joong, Sathiyanarayanan Ganesan, Bhatia Shashi Kant, Song Hun-Suk, Choi Yong-Keun, Kim Yun-Gon, Park Kyungmoon, Yang Yung-Hun
Department of Biological Engineering, College of Engineering, Konkuk University, 1 Hwayang-dong, Gwangjin-gu, Seoul, 05029, Republic of Korea.
Department of Biological Engineering, College of Engineering, Konkuk University, 1 Hwayang-dong, Gwangjin-gu, Seoul, 05029, Republic of Korea; Institute for Ubiquitous Information Technology and Applications (CBRU), Konkuk University, Seoul 143-701, Republic of Korea.
Enzyme Microb Technol. 2017 Sep;104:9-15. doi: 10.1016/j.enzmictec.2017.05.002. Epub 2017 May 13.
Cadaverine, a five-carbon diamine (1,5-diaminopentane), can be made by fermentation or direct bioconversion and plays an important role as a building block of polyamides. Lysine decarboxylase (CadA) transforms L-lysine to cadaverine and pyridoxal 5'-phosphate (PLP) can increases conversion rate and yield as a cofactor. Biotransformation of cadaverine using whole Escherichia coli cells that overexpress the lysine decarboxylase has many merits, such as the rapid conversion of l-lysine to cadaverine, possible application of high concentration reactions up to the molar level, production of less byproduct and potential reuse of the enzyme by immobilization. However, the supply of PLP, which is a cofactor of lysine decarboxylase, is the major bottleneck in this system. Therefore, we initiated our study on PLP precursors and PLP-related enzymes and discovered that pyridoxal (PL) can be a viable alternative to supply PLP. Among various PLP systems examined, pyridoxal kinase (PdxY) showed the highest conversion of PL to PLP, resulting in more than 60% conversion of l-lysine to cadaverine with lysine decarboxylase. When the reaction with 0.4M l-lysine, 0.2mM PL and more whole cells was performed, it resulted in an 80% conversion yield. Furthermore, when barium-alginate immobilization was applied, it showed a 90% conversion yield in 1h with PL, suggesting that it is compatible with developed whole-cell systems without a direct supply of exogenous PLP.
尸胺，一种五碳二胺（1,5 - 二氨基戊烷），可通过发酵或直接生物转化制得，作为聚酰胺的构建单元发挥着重要作用。赖氨酸脱羧酶（CadA）将L - 赖氨酸转化为尸胺，而磷酸吡哆醛（PLP）作为辅因子可提高转化率和产量。使用过表达赖氨酸脱羧酶的全大肠杆菌细胞进行尸胺的生物转化具有许多优点，例如L - 赖氨酸能快速转化为尸胺，可应用高达摩尔水平的高浓度反应，副产物产生较少，并且通过固定化有可能实现酶的重复利用。然而，赖氨酸脱羧酶的辅因子PLP的供应是该系统的主要瓶颈。因此，我们开展了关于PLP前体和PLP相关酶的研究，发现吡哆醛（PL）可以作为供应PLP的可行替代物。在研究的各种PLP系统中，吡哆醛激酶（PdxY）将PL转化为PLP的转化率最高，在赖氨酸脱羧酶作用下，L - 赖氨酸转化为尸胺的转化率超过60%。当使用0.4M L - 赖氨酸、0.2mM PL和更多全细胞进行反应时，转化率达到80%。此外，当应用钡 - 海藻酸盐固定化时，使用PL在1小时内转化率达到90%，这表明它与无需直接供应外源PLP的已开发全细胞系统兼容。
