High selective dehydrogenation of sugar by microbial enzyme

考察了葡萄糖氧化酶和半乳糖氧化酶的底物专一性，并对其氧化产物进行了分析。发现半乳糖、甘露糖和木糖被葡萄糖氧化酶氧化成相应的内酯。半乳糖和甘露糖的内酯最高得率分别为60%和20%。用半乳糖氧化酶将甲基D-半乳糖苷的C-6羟甲基通过醛氧化成相应的糖醛酸。分子中含有半乳糖基残基的一些低聚糖也被半乳糖氧化酶氧化。从蜂蜜二糖中分离得到纯净的6‘-羧基棉子糖，产率为41%；从棉籽糖中分离得到6“-羧基棉子糖，产率为14%。结果表明，半乳糖基的C-6醛容易氧化，在半乳糖氧化酶存在下进一步氧化为C-6羧基。与半乳糖基的氧化不同，一些糖醇如半乳糖醇和木糖醇被半乳糖氧化酶氧化成L糖，如L半乳糖和L木糖。在这种情况下，产生的L-半乳糖和L-木糖将通过形成吡喃糖环来稳定，不会发生进一步的氧化。如果碳水化合物被有氧同化，则总反应可视为氧化反应(多级脱氢)。将特定微生物的立体同化、区域同化或对映体同化应用于常规化学方法无法分离的碳水化合物的高选择性分离。D-没食子酸酯同化微生物、红色红酵母KM603、皮肤毛孢霉KM609和顶顶藻。用浓缩培养技术从活性污泥中分离得到KM 608，用于分离碳水化合物的C-2差向异构体、-异构体和DL-混合物。对其他一些特定微生物的选择性同化作用进行了评价。

Substrate specificities of glucose oxidase and galactose oxidase were examined, and their oxidation products were analyzed. It was found that galactose, mannose and xylose were ocidized to the corresponding lactones by glucose oxidase. Maximum yields of lactones were 60% for galactose and 20% for mannose. The C-6 hydroxymethyl group of mathyl D-galactopyranoside was oxidized to corresponding uronic acid via an aldehyde by galactose oxidase. Some oligosaccharides containing galactopyranosyl residues in the molecule were also oxidized by galactose oxidase. Pure and isolated 6'-carboxymelibiose was obtained with a yield of 41% from melibiose and 6"-carboxyraffinose was obtained with a yield of 14% from raffinose. It appears that the C-6 aldehyde of galactopyranosyl group is susceptible to oxidation and is further oxidized to the C-6 carboxyl group in the presence of galactose oxidase. In contrast to the oxidation of galactopyranosyl groups, some sugar alcohols, such as galactitol and xylitol, were oxidized by galactose oxidase to yield L-sugars, such as L-galactose and L-xylose, exclusively. In this case, the L-galactose and L-xylose produced will be stabilized by forming the pyranose ring, and no further oxidation occurs.If carbohydrates are ssimilated aerobically, the total reation can be regarded as the oxidation reaction (multistep dehydrogenation). Stereo, regio or enantiospecific assimilaltion by specific microbes was applied to the high selective separation of carbohydrates which was unable to separate by conventional chemical procedures. D-Allose-assimilating microbes, Rhodotorula rubra KM603, trichosporon cutaneum KM 609 and Acremonium sp. KM 608, obtained by enrichment culture technique from activated sludge, were used to separate the C-2 epimers, , -anomers and DL-mixtures of carbohydrates. Some other specific microbes were evaluated on their selective assimilation.