Datta A, Bettermann A, Kirk T K
University of Wisconsin Biotechnology Center, Madison.
Appl Environ Microbiol. 1991 May;57(5):1453-60. doi: 10.1128/aem.57.5.1453-1460.1991.
The specific enzymes associated with lignin degradation in solid lignocellulosic substrates have not been identified. Therefore, we examined extracts of cultures of Phanerochaete chrysosporium that were degrading a mechanical pulp of aspen wood. Western blot (immunoblot) analyses of the partially purified protein revealed lignin peroxidase, manganese-dependent peroxidase (MnP), and glyoxal oxidase. The dominant peroxidase, an isoenzyme of MnP (pI 4.9), was isolated, and its N-terminal amino acid sequence and amino acid composition were determined. The results reveal both similarities to and differences from the deduced amino acid sequences from cDNA clones of dominant MnP isoenzymes from liquid cultures. Our results suggest, therefore, that the ligninolytic-enzyme-encoding genes that are expressed during solid substrate degradation differ from those expressed in liquid culture or are allelic variants of their liquid culture counterparts. In addition to lignin peroxidase, MnP, and glyoxal oxidase, xylanase and protease activities were present in the extracts of the degrading pulp.
尚未鉴定出与固体木质纤维素底物中木质素降解相关的特定酶。因此，我们检测了正在降解白杨木机械浆的黄孢原毛平革菌培养物的提取物。对部分纯化蛋白质的蛋白质免疫印迹（免疫印迹）分析显示存在木质素过氧化物酶、锰依赖性过氧化物酶（MnP）和乙二醛氧化酶。分离出了占主导地位的过氧化物酶，即MnP的一种同工酶（pI 4.9），并测定了其N端氨基酸序列和氨基酸组成。结果揭示了与液体培养中占主导地位的MnP同工酶cDNA克隆推导的氨基酸序列的异同。因此，我们的结果表明，在固体底物降解过程中表达的木质素分解酶编码基因与液体培养中表达的基因不同，或者是其液体培养对应物的等位基因变体。除了木质素过氧化物酶、MnP和乙二醛氧化酶外，降解浆的提取物中还存在木聚糖酶和蛋白酶活性。
