PURIFICATION AND PROPERTIES OF 1,2-DEHYDRORETICULINE REDUCTASE FROM PAPAVER-SOMNIFERUM SEEDLINGS
PURIFICATION AND PROPERTIES OF 1,2-DEHYDRORETICULINE REDUCTASE FROM PAPAVER-SOMNIFERUM SEEDLINGS
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DOI：
10.1016/0031-9422(92)80020-f
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发表时间：
1992-03-01
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：
DEEKNAMKUL, W;ZENK, MH
1,2-脱氢网状番荔枝碱还原酶是一种 NADPH 依赖性酶，可将 1,2-脱氢网状番荔枝碱立体定向还原为 (R)-网状番荔枝碱，已在罂粟 (Papaver somniferum) 幼苗中发现。 该酶已通过硫酸铵沉淀和五个后续柱色谱步骤纯化至明显的电泳均质性。 分离的酶是M(r) 30 000的单一多肽，最适pH为8.5，最适温度为30度。 1,2-脱氢网状番荔枝碱和 NADPH 的表观 K(m) 值分别为 10 和 7-mu-M。 该酶介导 NADPH 的前 S-氢化物转移至 1,2-脱氢网状番荔枝碱的 C-1，具有高底物特异性；该酶不利用 1,2-脱氢去甲网状番荔枝碱和 1,2-脱氢椰壳碱。 该酶活性受到 (S)- 和 (R)-网脉番荔枝碱的抑制，I50 值分别为 0.05 和 0.10 mM。 还原酶是一种胞质酶，仅存在于含有吗啡喃生物碱的植物中。 这种高度物种、底物和立体特异性的酶催化提供 (R)-网脉番荔枝碱，以形成在该手性中心也具有 (R)-构型的吗啡喃生物碱。
1,2-Dehydroreticuline reductase, the NADPH-dependent enzyme which reduces stereospecifically 1,2-dehydroreticuline to (R)-reticuline has been discovered in seedlings of the opium poppy (Papaver somniferum). The enzyme has been purified to apparent electrophoretic homogeneity by ammonium sulphate precipitation and five subsequent column chromatography steps. The isolated enzyme is a single polypeptide with M(r) 30 000 and has a pH optimum at 8.5 and a temperature optimum at 30-degrees. The apparent K(m) values for 1,2-dehydroreticuline and NADPH are 10 and 7-mu-M, respectively. The enzyme mediates the transfer of the pro-S-hydride of NADPH to C-1 of 1,2-dehydroreticuline with high substrate specificity; neither 1,2-dehydronorreticuline nor 1,2-dehydrococlaurine are utilized by the enzyme. The enzyme activity is inhibited by (S)- and (R)-reticuline with I50 values of 0.05 and 0.10 mM, respectively. The reductase is a cytosolic enzyme and present only in morphinan alkaloid-containing plants. This highly species-, substrate- and stereospecific enzyme catalyses the provision of (R)-reticuline for the formation of morphinan alkaloids that possess also (R)-configuration at that chiral centre.