Rahmanpour Rahman, Bugg Timothy D H
Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK.
Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK.
Arch Biochem Biophys. 2015 May 15;574:93-8. doi: 10.1016/j.abb.2014.12.022. Epub 2015 Jan 3.
Members of the DyP family of peroxidases in Gram-positive bacteria have recently been shown to oxidise Mn(II) and lignin model compounds. Gram-negative pseudomonads, which also show activity for lignin oxidation, also contain dyp-type peroxidase genes. Pseudomonas fluorescens Pf-5 contains three dyp-type peroxidases (35, 40 and 55kDa), each of which has been overexpressed in Escherichia coli, purified, and characterised. Each of the three enzymes shows activity for oxidation of phenol substrates, but the 35kDa Dyp1B enzyme also shows activity for oxidation of Mn(II) and Kraft lignin. Treatment of powdered lignocellulose with Dyp1B in the presence of Mn(II) and hydrogen peroxide leads to the release of a low molecular weight lignin fragment, which has been identified by mass spectrometry as a β-aryl ether lignin dimer containing one G unit and one H unit bearing a benzylic ketone. A mechanism for release of this fragment from lignin oxidation is proposed.
最近研究表明，革兰氏阳性菌中的DyP家族过氧化物酶成员能够氧化Mn（II）和木质素模型化合物。同样表现出木质素氧化活性的革兰氏阴性假单胞菌也含有dyp型过氧化物酶基因。荧光假单胞菌Pf-5含有三种dyp型过氧化物酶（35、40和55kDa），每种酶都已在大肠杆菌中过表达、纯化并进行了表征。这三种酶都表现出氧化酚类底物的活性，但35kDa的Dyp1B酶还表现出氧化Mn（II）和硫酸盐木质素的活性。在Mn（II）和过氧化氢存在的情况下，用Dyp1B处理粉末状木质纤维素会导致释放出一种低分子量木质素片段，通过质谱鉴定为含有一个G单元和一个带有苄基酮的H单元的β-芳基醚木质素二聚体。本文提出了从木质素氧化中释放该片段的机制。
