Kiryu Takaaki, Nakano Hirofumi, Kiso Taro, Murakami Hiromi
Osaka Municipal Technical Research Institute, 6-50 Morinomiya 1-chome, Osaka 536-8553, Japan.
Biosci Biotechnol Biochem. 2008 Mar;72(3):833-41. doi: 10.1271/bbb.70701. Epub 2008 Mar 7.
A carbohydrate:acceptor oxidoreductase from Paraconiothyrium sp. was purified and characterized. The enzyme efficiently oxidized beta-(1-->4) linked sugars, such as lactose, xylobiose, and cellooligosaccharides. The enzyme also oxidized maltooligosaccharides, D-glucose, D-xylose, D-galactose, L-arabinose, and 6-deoxy-D-glucose. It specifically oxidized the beta-anomer of lactose. Molecular oxygen and 2,6-dichlorophenol indophenol were reduced by the enzyme as electron acceptors. The Paraconiothyrium enzyme was identified as a carbohydrate:acceptor oxidoreductase according to its specificity for electron donors and acceptors, and its molecular properties, as well as the N-terminal amino acid sequence. Further comparison of the amino acid sequences of lactose oxidizing enzymes indicated that carbohydrate:acceptor oxidoreductases belong to the same group as glucooligosaccharide oxidase, while they differ from cellobiose dehydrogenases and cellobiose:quinone oxidoreductases.
受体氧化还原酶进行了纯化和特性鉴定。该酶能高效氧化β-(1→4)连接的糖类，如乳糖、木二糖和纤维寡糖。该酶还能氧化麦芽寡糖、D-葡萄糖、D-木糖、D-半乳糖、L-阿拉伯糖和6-脱氧-D-葡萄糖。它特异性地氧化乳糖的β-异头物。分子氧和2,6-二氯酚靛酚作为电子受体被该酶还原。根据其对电子供体和受体的特异性、分子特性以及N端氨基酸序列，拟青霉属的这种酶被鉴定为碳水化合物：受体氧化还原酶。乳糖氧化酶氨基酸序列的进一步比较表明，碳水化合物：受体氧化还原酶与低聚葡萄糖氧化酶属于同一组，而它们与纤维二糖脱氢酶和纤维二糖：醌氧化还原酶不同。
