Biomimetic Study Of 4-Hydroxyphenylpyruvate Dioxygenase

Studies on the mechanism in reactions that degradating specific natural products using acitive sites of natural enzyme are becoming a magic weapon for scientists in bio-pharmcetuical field to make targeted drugs cheaper, more efficient and lower side effect. Therefore, manually establishment of model complexes to mimic acitive sites and the mechanism of natural enzyme is becoimg a hot topic in biological inorganic chemistry filed. To mimic the active sites and substituent effects of HPPD, we have completed the following work:One new model ligand (2-(phenylmethyl)pyridin-2-ylmethyl)amino)methyl)benzoic acid) L19H and five kinds of different para substituted phenyl pyruvic acid substrates (R:OH、 CH3、H、Br、NO2) have been designed, synthesized, and characterized by IR, ESI/MS, 1HNMR and melting point measurement.In order to bulid the structure of active site and the fuctional model ternary complex of HPPD, we coordinate ligands, substrates and Iron(II) acetate by the proportion 1:1:1. By HPLC-MS, we analyzed the products of the reaction between different model complex and dioxygen at room temperature. The conclusions of our study are as follows:Five kinds of different para-substituted substrates in enol-form can be degraded by all kinds of actives sites (2HislGlu,3His and 3His1Glu) respectively, and most are para substituted benzaldehyde (DKe1).Only with the active site 3HislGlu and 2HislGlu, model complex reacting with O2 can gain both HPPD and DKel function towards 4-hydroxyphenylpyruvate, since we have detected both homogentisic acid and p-hydroxybenzaldehyde which belong to HPPD products. However,3His active site only have DKe1 function, and what is more interesting is that other substituent substrates except 4-hydroxyphenylpyruvate only can be degradated into DKel product.DKe1 activity sequence:3His1Glu> 2HislGlu> 3His.