Mechanism of Organophosphonate Catabolism by Diiron Oxygenase PhnZ: A Third Iron-Mediated O-O Activation Scenario in Nature

	Mechanism of Organophosphonate Catabolism by Diiron Oxygenase PhnZ: A Third Iron-Mediated O-O Activation Scenario in Nature
	Zhao, Chongyang 1,2; Chen, Hui 1
刊名	ACS CATALYSIS
	2017-05-01
卷号	7 期号:5 页码:3521-3531
关键词	C-p Bond Cleavage Qm/mm Diiron Enzyme Superoxo Heterolytic O-o Cleavage Organophosphonate Catabolism Ferric-peroxide Phosphorus Oxidation
英文摘要	Diiron oxygenase PhnZ catalyzes the catabolism of organophosphonate (Pn) (R)-2-amino-1-hydroxyethylphos-phonic to glycine and inorganic phosphate (Pi). In this Pn catabolism way, PhnZ oxidatively cleaves the highly stable C-P bond in Pn to produce Pi. However, the mechanism of this enzyme that affords aquatic and marine bacteria in Pi-limited environments to utilize the most abundant environmental Pn (2-amino-ethylphosphonic acid) as the source of Pi is still unclear. In this work, extensive QM/MM calculations reveal that the mechanism of PhnZ consists of four consecutive steps: (1) rate-limiting alpha-H abstraction of Pn by Fe-III-superoxo; (2) formation of (FeOOC alpha)-O-III peroxide; (3) concerted O insertion into C-alpha-P bond of Pn initiated by "inverse" heterolytic O-O cleavage; and (4) phosphate hydrolysis to glycine and Pi. Intriguingly, the enzymatic reaction mechanism of PhnZ for the crucial breakage of the C-P bond is characterized by the "inverse" heterolytic O-O cleavage of (FeOOC alpha)-O-III intermediate, which renders the distal O atom more oxidative to oxygenate Pn than the homolytic O-O cleavage. In this way, PhnZ adopts a mechanism quite different from the related diiron oxygenase MIOX, with His62 residue playing an important role. This unusual "inverse" heterolytic O-O cleavage mode, apart from the well-known homolytic and "normal" heterolytic ones, constitutes a third iron-mediated O-O activation scenario in nature, which is expected to have its broad occurrence in oxidative transformation involving heteroatoms of sulfur and phosphorus.
语种	英语
内容类型	期刊论文
源URL	[http://ir.iccas.ac.cn/handle/121111/38409]
专题	化学研究所_光化学实验室
作者单位	1.Chinese Acad Sci, Beijing Natl Lab Mol Sci, Key Lab Photochem, CAS Res Educ Ctr Excellence Mol Sci,Inst Chem, Beijing 100190, Peoples R China 2.Univ Chinese Acad Sci, Beijing 100049, Peoples R China
推荐引用方式 GB/T 7714	Zhao, Chongyang,Chen, Hui. Mechanism of Organophosphonate Catabolism by Diiron Oxygenase PhnZ: A Third Iron-Mediated O-O Activation Scenario in Nature[J]. ACS CATALYSIS,2017,7(5):3521-3531.
APA	Zhao, Chongyang,&Chen, Hui.(2017).Mechanism of Organophosphonate Catabolism by Diiron Oxygenase PhnZ: A Third Iron-Mediated O-O Activation Scenario in Nature.ACS CATALYSIS,7(5),3521-3531.
MLA	Zhao, Chongyang,et al."Mechanism of Organophosphonate Catabolism by Diiron Oxygenase PhnZ: A Third Iron-Mediated O-O Activation Scenario in Nature".ACS CATALYSIS 7.5(2017):3521-3531.