Oxidase, superoxide dismutase, and hydrogen peroxide reductase activities of methanobactin from types I and II methanotrophs
Oxidase, superoxide dismutase, and hydrogen peroxide reductase activities of methanobactin from types I and II methanotrophs
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DOI：
10.1016/j.jinorgbio.2008.02.003
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发表时间：
2008-08-01
影响因子：
3.9
通讯作者：
DiSpirito, Alan A.
中科院分区：
文献类型：
--
作者：
Choi, Dong W.;Semrau, Jeremy D.;DiSpirito, Alan A.
甲烷氧化菌素（MB）是一种铜结合色肽，似乎参与甲烷的氧化膜相关或颗粒甲烷单加氧酶（pMMO）。为了研究这种潜在的生理作用，MB从三个不同的甲烷氧化菌的氧化还原和催化性能进行了研究，在存在和不存在O-2。无金属MB从II型甲烷氧化菌Methylosinus trichosporium OB 3b，但不是从I型甲烷氧化菌Methylococcus capsulatus Bath或Methylomicrobium album BG 8，被各种还原剂，包括NADH和duroquinol还原，并催化O-2还原为O-2（-中心点）。含铜MB（Cu-MB）从所有三个甲烷氧化菌表现出几个有趣的特性，包括还原酶依赖的氧化酶活性，歧化的O-2（-中心点）到H2 O2，和还原剂依赖的还原H2 O2到H2O。超氧化物歧化酶样和过氧化氢还原酶活性的Cu-mb分别高4和1个数量级，比观察到的氧化酶活性。结果表明，铜mb从所有三个甲烷氧化菌的氧化还原活性分子和氧自由基清除剂，具有解毒超氧化物和过氧化氢的能力，而不会形成与芬顿反应的羟基自由基。如先前用来自发孢酵母OB 3b的Cu-mb观察到的，来自两种I型甲烷氧化菌的Cu-mb刺激pMMO活性。然而，与以前的研究相比，使用来自发孢酵母OB 3b的MB，pMMO活性在低铜与MB比率下不受来自两种I型甲烷氧化菌的MB的抑制。(c)2008年爱思唯尔公司All rights reserved.
Methanobactin (mb) is a copper-binding chromopeptide that appears to be involved in oxidation of methane by the membrane-associated or particulate methane monooxygenase (pMMO). To examine this potential physiological role, the redox and catalytic properties of mb from three different methanotrophs were examined in the absence and presence of O-2. Metal free mb from the type II methanotroph Methylosinus trichosporium OB3b, but not from the type I methanotrophs Methylococcus capsulatus Bath or Methylomicrobium album BG8, were reduced by a variety of reductants, including NADH and duroquinol, and catalyzed the reduction of O-2 to O-2(-center dot). Copper-containing mb (Cu-mb) from all three methanotrophs showed several interesting properties, including reductase dependent oxidase activity, dismutation of O-2(-center dot) to H2O2, and the reductant dependent reduction of H2O2 to H2O. The superoxide dismutase-like and hydrogen peroxide reductase activities of Cu-mb were 4 and 1 order(s) of magnitude higher, respectively, than the observed oxidase activity. The results demonstrate that Cu-mb from all three methanotrophs are redox-active molecules and oxygen radical scavengers, with the capacity to detoxify both superoxide and hydrogen peroxide without the formation of the hydroxyl radicals associated with Fenton reactions. As previously observed with Cu-mb from Ms. trichosporium OB3b, Cu-mb from both type I methanotrophs stimulated pMMO activity. However, in contrast to previous studies using mb from Ms. trichosporium OB3b, pMMO activity was not inhibited by mb from the two type I methanotrophs at low copper to mb ratios. (c) 2008 Elsevier Inc. All rights reserved.