Tyrosine decarboxylase (TyDC), a pyridoxal-5′-phosphate (PLP)-dependent aromatic amino acid decarboxylase, catalyzes the decarboxylation of l-tyrosine (Tyr) to generate the important biogenic tyramine. This amine was reported to be a biosynthetic precursor of the Amaryllidaceae alkaloids, a group of pharmaceutically important natural products. Herein, we cloned two TyDC-encoding genes from Lycoris radiata, a galanthamine (GAL, a characteristic Amaryllidaceae alkaloid)-producing and medicinally and ornamentally important perennial herbaceous plant. Heterologous expression of LrTyDCs in Escherichia coli and the following purification gave recombinant LrTyDCs to homogeneity for enzymatic reactions. Tyramine was detected and validated by HPLC–DAD and HRESIMS analyses of the LrTyDC-catalyzed reaction mixture, which revealed the catalytic decarboxylation activity of LrTyDCs. The transcriptional LrTyDCs were detected in all tissues of L. radiata by quantitative real-time PCR analyses. The present works demonstrated that TyDC-catalyzed decarboxylation reaction is a key step to generate the non-catechol biosynthetic precursor of the Amaryllidaceae alkaloids.

酪氨酸脱羧酶（TyDC）是一种吡ido醛5'-磷酸（PLP）依赖性芳香族氨基酸脱羧酶，可催化1-酪氨酸（Tyr）的脱羧反应，从而产生重要的生物酪胺。据报道，该胺是金莲花科生物碱的生物合成前体，该生物碱是一组药学上重要的天然产物。在这里，我们从产石蒜（Lycoris radiata），一种加兰他敏（GAL，一种特有的芳科植物生物碱）的生产和药用和观赏重要的多年生草本植物中克隆了两个TyDC编码基因。LrTyDC s在大肠杆菌中的异源表达随后的纯化使重组LrTyDCs达到均一的酶促反应。通过LrTyDC催化的反应混合物的HPLC-DAD和HRESIMS分析检测并验证了酪胺，这揭示了LrTyDC的催化脱羧活性。通过定量实时PCR分析，在辐射乳杆菌的所有组织中检测到转录的LrTyDC s 。目前的工作表明，TyDC催化的脱羧反应是生成芳樟科生物碱的非邻苯二酚生物合成前体的关键步骤。