STRUCTURAL STUDY OF ARABIDOPSIS CAD5 (CINNAMYL ALCOHOL DEHYDROGENASE 5) ENZYME

该子项目是利用 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得主要资金， 因此可以在其他CRISP条目中表示。列出的机构是 中心，不一定是研究者的机构。 木质素、木脂素和木脂素是一类非常重要的苯丙素类化合物。它们在植物防御中起着重要作用，帮助宿主区分生物病原体和共生的非病原体。更重要的是，苯丙素途径的各种最终代谢产物具有重要的药理作用，特别是在癌症预防中。尽管这些化合物在植物生物学和人类健康中的重要性，但尚未对所涉及的酶进行系统研究。我们已经研究了参与苯丙素类生物合成途径的最重要的酶之一。肉桂醇脱氢酶5（CAD 5）酶描述了一类催化各种苯基丙烯醛衍生物还原的NADPH依赖性酶。通常，该反应产生几种单木酚，后者主要是木酚素的前体。我们已经使用旋转阳极（Rigaku，Raxis-IV）获得了分辨率为2.5的CAD 5晶体（P41212）的衍射数据。然而，我们不能进行分子置换，因为没有任何类似的蛋白质解决。因此，必须使用MAD。除了MAD数据外，高分辨率数据和复杂晶体（AtCAD 5-辅因子/底物/产物）衍射数据对于研究AtCAD 5独特立体特异性转化的确切机制是绝对必要的。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Lignins, lignans and isoflavonoids represent very important class of phenylpropanoids. They play important roles in plant defense, helping hosts discriminate between biological pathogens and symbiotic non-pathogens. More importantly, various final metabolic products of phenylpropanoid pathway have important pharmacological roles, especially in cancer prevention. Despite the importance of these compounds in plant biology and in human health, systematic studies on the enzymes involved have not been done. We have studied one of the most important enzymes involved in phenylpropanoid biosynthesis pathways. Cinnamyl alcohol Dehydrogenase 5 (CAD5) enzyme depicts a class of NADPH-dependent enzymes catalyzing the reduction of various phenylpropenyl aldehyde derivatives. Generically, this reaction makes several monolignols, with the latter mainly being precursors of lignans. We have already obtained the diffraction data of CAD5 crystal (P41212) with 2.5 ¿ resolutions using a rotating anode (Rigaku, Raxis-IV). However, we couldn't perform the molecular replacement because there is no any similar protein solved. Therefore, MAD must be used. In addition to MAD data, the high resolution data and complex crystal (AtCAD5-cofactor/substrate/product) diffraction data are absolutely required for the studying of the exact mechanism of its unique stereospecific conversion of AtCAD5.