High selective dehydrogenation of sugar by microbial enzyme

研究了葡萄糖氧化酶和半乳糖氧化酶的底物特异性，并对其氧化产物进行了分析。葡萄糖氧化酶可将半乳糖、甘露糖和木糖氧化为相应的内酯。半乳糖和甘露糖的内酯产率分别为60%和20%。半乳糖氧化酶经醛反应，将甲基d -半乳糖吡喃苷的C-6羟甲基氧化为醛酸。一些分子中含有半乳糖吡喃基残基的低聚糖也被半乳糖氧化酶氧化。从糖二糖中分离得到纯度为41%的6′-羧基糖二糖，从棉子糖中分离得到6′-羧基糖，产率为14%。半乳糖醛基的C-6醛易氧化，在半乳糖氧化酶存在下进一步氧化为C-6羧基。与半乳糖吡喃基的氧化相反，一些糖醇，如半乳糖醇和木糖醇，被半乳糖氧化酶氧化，只产生l -糖，如l -半乳糖和l -木糖。在这种情况下，生成的l -半乳糖和l -木糖会通过形成吡喃糖环而稳定下来，不会发生进一步的氧化。如果碳水化合物是有氧同化的，则整个反应可视为氧化反应（多步脱氢）。对传统化学方法无法分离的碳水化合物进行了立体、区域或对映体同化。利用富集培养技术从活性污泥中分离得到的d - allose同化微生物红红酵母KM603、皮肤毛孢霉KM 609和顶孢霉KM 608，对碳水化合物的C-2外显体、-异聚物和dl混合物进行了分离。对其他一些特定微生物的选择性同化进行了评价。

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.