Improved manganese-oxidizing activity of DypB, a peroxidase from a lignolytic bacterium.
Improved manganese-oxidizing activity of DypB, a peroxidase from a lignolytic bacterium.
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DOI：
10.1021/cb300608x
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发表时间：
2013-04-19
影响因子：
4
通讯作者：
Eltis, Lindsay D.
中科院分区：
文献类型：
--
作者：
Singh, Rahul;Grigg, Jason C.;Qin, Wei;Kadla, John F.;Murphy, Michael E. P.;Eltis, Lindsay D.
DypB是来自木质素分解土壤细菌Rhodococcus jostii RHA 1的染料脱色过氧化物酶，催化二价锰（Mn 2+）的过氧化物依赖性氧化，尽管效率低于真菌锰过氧化物酶。取代Asn 246，远端血红素残基，丙氨酸，增加了酶的表观kcat和kcat/Km值Mn 2+的80和15倍，分别。N246 A变体的2.2 μ m分辨率的X射线晶体结构显示Mn 2+结合在血红素边缘的酸性残基的口袋内，这让人想起真菌锰过氧化物酶中的结合位点，并且与另一种细菌Mn 2+氧化过氧化物酶的结合位点非常不同。第一配位球完全由溶剂组成，与变体对Mn 2+的高Km（17 ± 2 mM）一致。N246 A催化硬木硫酸盐木质素及其溶剂提取组分的锰依赖性转化。两种主要降解产物分别被鉴定为2，6-二甲氧基苯醌和4-羟基-3，5-二甲氧基苯甲醛。这些结果突出了细菌酶作为生物催化剂转化木质素的潜力。
DypB, a dye-decolorizing peroxidase from the lignolytic soil bacterium Rhodococcus jostii RHA1, catalyzes the peroxide-dependent oxidation of divalent manganese (Mn2+), albeit less efficiently than fungal manganese peroxidases. Substitution of Asn246, a distal heme residue, with alanine, increased the enzyme’s apparent kcat and kcat/Km values for Mn2+ by 80- and 15-fold, respectively. A 2.2 Å resolution X-ray crystal structure of the N246A variant revealed the Mn2+ to be bound within a pocket of acidic residues at the heme edge, reminiscent of the binding site in fungal manganese peroxidase and very different to that of another bacterial Mn2+-oxidizing peroxidase. The first coordination sphere was entirely comprised of solvent, consistent with the variant’s high Km for Mn2+ (17 ± 2 mM). N246A catalyzed the manganese-dependent transformation of hard wood kraft lignin and its solvent-extracted fractions. Two of the major degradation products were identified as 2,6-dimethoxybenzoquinone and 4-hydroxy-3,5-dimethoxybenzaldehyde, respectively. These results highlight the potential of bacterial enzymes as biocatalysts to transform lignin.
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DOI：
10.1107/s0907444905036693
发表时间：
2006-01-01
影响因子：
2.2
作者：
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通讯作者：
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影响因子：
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作者：
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通讯作者：
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影响因子：
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作者：
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通讯作者：
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