Functionalization of unactivated sp2-hybridized carbon atoms

描述（由申请人提供）：自然界已经进化出多种切割未活化的碳-氢键的策略，以使惰性碳中心官能化。这些反应总是使用金属辅因子来产生强大的氧化剂，这些氧化剂可以从碳中心提取氢原子进行官能化，产生碳中心自由基。在所有涉及H提取的成熟酶机制中，裂解的C-H键是sp3-杂交的，并且相关的均裂键解离能（BDE）小于（或等于）甲烷的104 kcal/mol特征。最近，越来越多的反应已被确定，这意味着功能化的碳中心是sp2杂化与键的断裂，具有大于105千卡/摩尔的溴化二苯醚。该项目旨在表征三个这样的酶促反应，涉及甲基化，甲硫基化和羟基化的sp2杂化碳中心。前两个反应是由属于自由基SAM超家族的酶催化的，而第三个反应是由Fe（II）-和？酮戊二酸依赖性加氧酶家族这些研究的结果应显着扩大我们的理解自然的未活化的sp2杂化碳中心的功能化的策略，并揭示了反应机制的细节，可能会被证明在设计这些过程的治疗性抑制剂实际上是有用的。)

DESCRIPTION (provided by applicant): Nature has evolved a variety of strategies to cleave unactivated carbon-hydrogen bonds in order to functionalize inert carbon centers. These reactions invariably employ metallocofactors to create powerful oxidants that can abstract hydrogen atoms from the carbon centers to be functionalized, generating carbon-centered radicals. In all well-established enzyme mechanisms involving H abstraction, the cleaved C-H bonds are sp3-hybridized, and the associated homolytic bond-dissociation energies (BDEs) are less than (or equal to) the 104 kcal/mol characteristic of methane. Recently, a growing number of reactions have been identified that imply functionalization of carbon centers that are sp2-hybridized with cleavage of bonds that have BDEs of greater than 105 kcal/mol. This project aims to characterize three such enzymatic reactions involving methylation, methylthiolation, and hydroxylation of sp2-hybridized carbon centers. The first two reactions are catalyzed by enzymes belonging to the radical-SAM superfamily, while the third is catalyzed by an enzyme in the Fe(II)- and ?-ketoglutarate-dependent oxygenase family. The results of these studies should significantly expand our understanding of Nature's strategies for functionalization of unactivated sp2-hybridized carbon centers and reveal details of reaction mechanisms that may prove practically useful in design of therapeutic inhibitors of these processes. )