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

本子项目是利用由NIH/NCRR资助的中心赠款提供的资源的众多研究子项目之一。子项目和研究者（PI）可能已经从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。列出的机构是中心的，不一定是研究者的机构。木质素、木脂素和异黄酮是一类重要的苯丙素。它们在植物防御中发挥重要作用，帮助寄主区分生物病原体和共生非病原体。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，特别是在癌症预防方面。尽管这些化合物在植物生物学和人类健康中具有重要意义，但尚未对所涉及的酶进行系统研究。我们研究了苯丙素生物合成途径中最重要的酶之一。肉桂醇脱氢酶5 （CAD5）是一类nadph依赖的酶，催化各种苯丙烯醛衍生物的还原。一般来说，这个反应产生几种单脂醇，后者主要是木脂素的前体。我们已经使用旋转阳极（Rigaku, Raxis-IV）获得了2.5分辨率的CAD5晶体（P41212）的衍射数据。然而，我们无法进行分子替换，因为没有任何类似的蛋白质被解决。因此，必须使用MAD。为了研究AtCAD5独特的立体定向转化的确切机理，除了MAD数据外，还绝对需要高分辨率数据和复杂晶体（AtCAD5-协因子/底物/产物）衍射数据。

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.