Marín-Zamora María Elisa, Rojas-Melgarejo Francisco, García-Canovas Francisco, García-Ruiz Pedro Antonio
Grupo de Química de Carbohidratos y Biotecnología de Alimentos (QCBA), Departamento de Química OrgAnica, Facultad de Química, Universidad de Murcia, E-30100 Espinardo, Murcia, Spain.
J Agric Food Chem. 2007 May 30;55(11):4569-75. doi: 10.1021/jf0701178. Epub 2007 May 9.
Mushroom tyrosinase was immobilized from an extract onto glass beads covered with the cross-linked totally cinnamoylated derivates of d-sorbitol (sorbitol cinnamate) and glycerine (glycerine cinnamate). The enzyme was immobilized onto the support by direct adsorption, and the quantity of immobilized tyrosinase was higher for sorbitol cinnamate, the support with the higher number of esterified hydroxyls per unit of monosacharide, than for glycerine cinnamate. The results obtained from the stereospecificity study of the monophenolase and diphenolase activity of immobilized mushroom tyrosinase are reported. The enantiomers L-tyrosine, DL-tyrosine, D-tyrosine, L-dopa, DL-dopa, D-dopa, L-alpha-methyldopa, DL-alpha-methyldopa, L-isoprenaline, DL-isoprenaline, L-adrenaline, DL-adrenaline, L-noradrenaline, and D-noradrenaline were assayed with tyrosinase immobilized on a chiral support (sorbitol cinnamate), whereas L-tyrosine, DL-tyrosine, D-tyrosine, L-dopa, DL-dopa, D-dopa, L-alpha-methyldopa, and DL-alpha-methyldopa were assayed with tyrosinase immobilized on a nonchiral support (glycerine cinnamate). The same Vmax(app) values for each series of enantiomers were obtained. However, the Km(app) values were different, the l isomers showing lower values than the dl isomers, whereas the highest Km(app) value was obtained with d isomers. No difference was observed in the stereospecificity of tyrosinase immobilized on a chiral (sorbitol cinnamate) or nonchiral (glycerine cinnamate) support.
将蘑菇酪氨酸酶从提取物固定到覆盖有交联的完全肉桂酰化的d -山梨醇衍生物（山梨醇肉桂酸酯）和甘油衍生物（甘油肉桂酸酯）的玻璃珠上。通过直接吸附将酶固定到载体上，对于山梨醇肉桂酸酯（每单位单糖酯化羟基数量更多的载体），固定化酪氨酸酶的量高于甘油肉桂酸酯。报道了固定化蘑菇酪氨酸酶的单酚酶和二酚酶活性的立体特异性研究结果。用固定在手性载体（山梨醇肉桂酸酯）上的酪氨酸酶测定对映体L -酪氨酸、DL -酪氨酸、D -酪氨酸、L -多巴、DL -多巴、D -多巴、L -α -甲基多巴、DL -α -甲基多巴、L -异丙肾上腺素、DL -异丙肾上腺素、L -肾上腺素、DL -肾上腺素、L -去甲肾上腺素和D -去甲肾上腺素，而用固定在非手性载体（甘油肉桂酸酯）上的酪氨酸酶测定L -酪氨酸、DL -酪氨酸、D -酪氨酸、L -多巴、DL -多巴、D -多巴、L -α -甲基多巴和DL -α -甲基多巴。每组对映体获得相同的Vmax(app)值。然而，Km(app)值不同，l异构体的值低于dl异构体，而d异构体的Km(app)值最高。固定在手性（山梨醇肉桂酸酯）或非手性（甘油肉桂酸酯）载体上的酪氨酸酶的立体特异性没有差异。
