The Interaction of Hydroxymandelate Synthase with the 4-Hydroxyphenylpyruvate Dioxygenase Inhibitor: NTBC.
The Interaction of Hydroxymandelate Synthase with the 4-Hydroxyphenylpyruvate Dioxygenase Inhibitor: NTBC.
复制标题
羟基扁桃酸合酶与 4-羟基苯基丙酮酸双加氧酶抑制剂的相互作用：NTBC。
DOI：
10.1016/j.ica.2007.07.036
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发表时间：
2008
影响因子：
2.8
通讯作者：
Moran,GrahamR
中科院分区：
文献类型：
--
作者：
Conrad,JohnA;Moran,GrahamR
羟基扁桃酸合成酶(HMS)催化对羟基苯甘氨酸的形成，对羟基苯甘氨酸是多环非核糖体多肽抗生素(如万古霉素)的一种递归亚结构。HMS使用与4-羟基苯丙酮酸双加氧酶(HPPD)、4-羟基苯基丙酮酸(HPP)和O2相同的底物，还进行双氧合反应。两者的不同之处在于插入了第二个氧原子，HMS将该原子定向到底物的苄基碳上，而HPPD则将芳香族C1碳羟化。我们已经证明HMS将与NTBC结合，NTBC是一种除草剂/治疗剂，其作用模式是基于对HPPD的抑制。尽管HMS活性部位的残留量与已知的与HPPD中的抑制剂接触的残留量不同，但仍会发生这种情况。此外，NTBC与HMS结合的最小动力学机制与HPPD观察到的仅略有不同。主要的区别是观察到三种电荷转移物种在缔合过程中积累。第一个形成的可逆络合物的弱解离常数为520μM，随后形成的两个电荷转移络合物的速率常数分别为2.7s−1和0.67s−1。与HPPD的情况一样，最终的络合物具有最强烈的电荷转移，没有观察到解离，对氧气没有反应。
Hydroxymandelate synthase (HMS) catalyzes the committed step in the formation of para-hydroxyphenylglycine, a recurrent substructure of polycyclic non-ribosomal peptide antibiotics such as vancomycin. HMS uses the same substrates as 4-hydroxyphenylpyruvate dioxygenase (HPPD), 4-hydroxyphenylpyruvate (HPP) and O2, and also conducts a dioxygenation reaction. The difference between the two lies in the insertion of the second oxygen atom, HMS directing this atom onto the benzylic carbon of the substrate while HPPD hydroxylates the aromatic C1 carbon. We have shown that HMS will bind NTBC, a herbicide/therapeutic whose mode of action is based on the inhibition of HPPD. This occurs despite residue differences at the active site of HMS from those known to contact the inhibitor in HPPD. Moreover, the minimal kinetic mechanism for association of NTBC to HMS differs only slightly from that observed with HPPD. The primary difference is that three charge-transfer species are observed to accumulate during association. The first reversible complex forms with a weak dissociation constant of 520μM, the subsequent two charge-transfer complexes form with rate constants of 2.7s−1and 0.67s−1. As was the case for HPPD, the final complex has the most intense charge-transfer, is not observed to dissociate, and is unreactive towards dioxygen.