Bertoldi Mariarita, Cellini Barbara, Maras Bruno, Voltattorni Carla Borri
Dipartimento di Scienze Neurologiche e della Visione, Sezione di Chimica Biologica, Università di Verona, Italy.
FEBS Lett. 2005 Sep 26;579(23):5175-80. doi: 10.1016/j.febslet.2005.08.029.
The reactions of Dopa decarboxylase (DDC) with l- and d-enantiomers of tryptophan methyl ester are described. Although both the enantiomers bind to the active site of the enzyme with similar affinity, their binding modes are different. l-enantiomer binds in an unproductive mode, while d-enantiomer acts as an oxidative deamination substrate. For the first time a quinonoid has been detected as intermediate of this reaction. By using rapid-scanning stopped-flow kinetic technique rate constants for formation and decay of this species have been determined. All these data, besides validating the functional DDC active site model, represent an important step toward the elucidation of the catalytic pathway of oxidative deamination.
描述了多巴脱羧酶（DDC）与色氨酸甲酯的l-和d-对映体的反应。尽管两种对映体以相似的亲和力结合到酶的活性位点，但其结合模式不同。l-对映体以非生产性模式结合，而d-对映体作为氧化脱氨底物。首次检测到醌类作为该反应的中间体。通过使用快速扫描停流动力学技术，已确定了该物种形成和衰变的速率常数。所有这些数据，除了验证功能性DDC活性位点模型外，还代表了阐明氧化脱氨催化途径的重要一步。
