Purification and characterization of coclaurine N-methyltransferase from cultured Coptis japonica cells
作者:Kum-Boo Choi、Takashi Morishige、Fumihiko Sato
DOI:10.1016/s0031-9422(00)00481-7
日期:2001.4
S-Adenosyl-L-methionine (SAM): coclaurine N-methyltransferase (CNMT), which catalyzes the transfer of a methyl group from S-adenosyl-L-methionine to the amino group of the tetrahydrobenzylisoquinoline alkaloid coclaurine. was purified 340-fold from Coptis japonica cells in 1% yield to give an almost homogeneous protein. The purified enzyme, which occurred as a homotetramer with a native Mr of 160 kDa
S-腺苷-L-甲硫氨酸 (SAM):椰油碱 N-甲基转移酶 (CNMT),催化甲基从 S-腺苷-L-甲硫氨酸转移到四氢苄基异喹啉生物碱椰油碱的氨基。以 1% 的产率从日本黄连细胞中纯化 340 倍,得到几乎均质的蛋白质。纯化的酶以同源四聚体形式出现,天然 Mr 为 160 kDa(凝胶过滤色谱),亚基 Mr 为 45 kDa(SDS-聚丙烯酰胺凝胶电泳),其最适 pH 值为 7.0,pI 为 4.2。而 (R)-coclaurine 是酶活性的最佳底物,Coptis CNMT 具有广泛的底物特异性,没有立体特异性 CNMT 甲基化去甲月桂醇内酯、6,7-二甲氧基-1,2,3,4-四氢异喹啉和 1-甲基-6,7 -二羟基-1,2,3,4-四氢异喹啉。该酶不需要任何金属离子。对氯汞苯甲酸盐和碘乙酰胺不抑制 CNMT 活性,但添加 5 mM 的 Co2+、Cu2+ 或 Mn2+ 分别严重抑制了 75%、47%