Chloroperoxidase, a Janus Enzyme

Abstract

Chloroperoxidase is a versatile fungal heme-thiolate protein that catalyzes a variety of one-electron and two-electron oxidations. We report here that the alkylation of an essential histidine residue showed no effect on the one-electron peroxidations but inhibited two-electron oxidations. The pH profiles of different peroxidative substrates showed optimal activities at varying pH values for the same enzyme. 2-Allylphenol and substituted ortho-phenolics showed efficient peroxidations. Also, substrates excluded from the active site (or with no favorable positioning at the heme center or heme edge) were converted in the peroxidation reaction. While hydrogen peroxide serves as the superior activator in the two-electron oxidations, small alkylhydroperoxides give much better rates for peroxidation reactions. All the above observations indicate that one-electron oxidations are mechanistically quite different from the two-electron oxidations catalyzed by chloroperoxidase. We propose that the peroxidatic substrates interact predominantly outside the heme active site, presumably at the surface of the enzyme.

Immobilization of Chloroperoxidase in Metal Organic Framework and Its Catalytic Performance

“…吸附法 [7,8] [19] , 目前被认为是过氧化物 酶家族中催化活性最广泛的酶之一, 因此 CPO 的应用 范围非常广, 尤其是在不对称有机合成 [20,21] 以及环境污 染物降解 [22,23] 等方面的应用引人瞩目. 衍射峰位相同, 也与文献报道的特征衍射峰相符(2θ＝ 7.4°、12.7°、18.0°) [25] .…”

A Lifetime of Playing with Enzymes

“…Early experiments showed that chemical modification of His 148 destroyed the halogenation activity of CPO (69). Much later, in a paper entitled "Chloroperoxidase, a Janus Enzyme," we showed that modification of His 148 did not affect the ability of CPO to catalyze one-electron oxidations (70). We concluded that all two-electron oxidations carried out by CPO occur at the heme active site of the enzyme and require the participation of His…”

Nuclear Magnetic Resonance Spectroscopic and Computational Investigations of Chloroperoxidase Catalyzed Regio- and Enantio-Selective Transformations

“…However, the epoxidation activity of the mutant was surprisingly shown to be enhanced ∼2.5 fold compared to the native CPO [72]. Furthermore, the chemical modification of His 105, a residue adjacent to Glu 183, was found to destroy the CPO's halogenation activity [73]. In sum, how residues are involved in the mechanism is still not quite understood.…”