S-ADENOSYL-L-METHIONINE - 3'-HYDROXY-N-METHYL-(S)-COCLAURINE-4'-O-METHYL TRANSFERASE, A REGIOSELECTIVE AND STEREOSELECTIVE ENZYME OF THE (S)-RETICULINE PATHWAY
S-ADENOSYL-L-METHIONINE - 3'-HYDROXY-N-METHYL-(S)-COCLAURINE-4'-O-METHYL TRANSFERASE, A REGIOSELECTIVE AND STEREOSELECTIVE ENZYME OF THE (S)-RETICULINE PATHWAY
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DOI：
10.1016/0031-9422(90)85265-h
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发表时间：
1990-01-01
期刊：
影响因子：
3.8
通讯作者：
ZENK, MH
中科院分区：
文献类型：
--
作者：
FRENZEL, T;ZENK, MH
一种新的酶SAM：3“-羟基-N-甲基-（S）-乌药碱-4”-O-甲基转移酶（4“-OMT）存在于四个科的几种含异喹啉的植物细胞培养物中。该酶纯化约400倍，从Berglandkoetineana细胞培养物。最终制备物仅由两种蛋白质组成，即4“-OMT和SAM：去甲乌药碱-6-O-甲基转移酶。通过标准程序分离两种酶失败。4“-OMT是一种高度特异性的酶，在SAM存在下催化甲基转移到具有绝对（S）-构型的苄基异喹啉生物碱的C-4”-羟基上，并且在C环的C-3“-和C-4”-位上具有相邻的羟基。该酶的最适pH为8.3，天然底物为3 ″-羟基-N-甲基-（S）-乌药碱（Km = 4.5 μ M; Km SAM = 30 μ M）。该酶是单一多肽（Mr 40 × 100）。103通过SDS），并有效地抑制产品和在较小程度上由其他生物碱。该酶在室温下的半衰期为三天，如果储存在-20 ℃（在20%甘油中），则稳定一年以上。
A new enzyme SAM: 3''-hydroxy-N-methyl-(S)-coclaurine-4''-O-methyltransferase (4''-OMT) was found in cell cultures of several isoquinoline-containing plant species belonging to four plant families. The enzyme was purified ca 400-fold from Berberis koetineana cells cultures. The final preparation consisted of only two proteins, namely the 4''-OMT and SAM: norcoclaurine-6-O-methyltransferase. Separation of both enzymes by standard procedures failed. The 4''-OMT is a highly specific enzyme catalysing in the presence of SAM the transfer of a methyl group onto the C-4'' hydroxyl group of benzylisoquinoline alkaloids with absolute (S)-configuration at C-1 and possessing adjacent hydroxyl groups in the C-3''- and C-4'' position of ring C. The pH optimum of the enzyme is 8.3 and the natural substrate is 3''-hydroxy-N-methyl-(S)-coclaurine (Km = 4.5 .mu.M; Km SAM = 30 .mu.M). The enzyme is a single polypeptide (Mr 40 .times. 103 by SDS) and is potently inhibited by the product and to a lesser extent by other alkaloids. The enzyme has a half life of three days at room temperature and is stable for more than a year if stored at -20.degree.C (in 20% glycerol).