Aureobacterium barkeri strain KDO-37-2 (ATCC 49977) and KDO aldolase (EC 4.1.2.23) isolated therefrom are disclosed. The KDO aldolase is further disclosed to have a broad substrate specificity with respect to its reverse reaction, i.e. the condensation of aldoses with pyruvate to form a wide range of 2-keto-3-deoxy-onic acids, including 2-keto-3-deoxy-nonulosonic acid, 2-keto-3-deoxy-octulosonic acid, 2-keto-3-deoxy-heptulosonic acid, and 2-keto-3-deoxy-hexulosonic acid. In particular, 3-deoxy-D-manno-2-octulosonic acid (D-KDO), a vital component of lipopolysaccharides found in the bacterial outer membrane may be synthesized from D-arabinose and pyruvate in 67% yield. Additionally, protected forms of the KDO aldolase products, e.g. hexaacetyl 2-keto-3-deoxy-nonulosonic acid and pentaacetyl 2-keto-3-deoxy-octulosonic acid, may be decarboxylated to form the corresponding 2-deoxy-aldoses, e.g. 2-deoxy-octulose and 2-deoxy-heptulose respectively.
本文介绍了从Aureobacterium barkeri菌株KDO-37-2(A
TCC 49977)中分离出的KDO aldolase(
EC 4.1.2.23)。进一步揭示了KDO aldolase在反应方面具有广泛的底物特异性,即将醛糖与
丙酮缩合形成各种2-酮基-3-去氧酸,包括2-酮基-3-去氧-非烯酸,2-酮基-3-去氧-八烯酸,2-酮基-3-去氧-
庚烯酸和2-酮基-3-去氧-己烯酸。特别地,可以从
D-阿拉伯糖和
丙酮中合成3-去氧-D-曼诺-2-八烯酸(D-KDO),这是细菌外膜中发现的脂
多糖的重要组成部分,产率为67%。此外,KDO aldolase产物的受保护形式,例如六乙酰基2-酮基-3-去氧-非烯酸和五乙酰基2-酮基-3-去氧-八烯酸,可以脱羧形成相应的2-去氧醛糖,例如2-去氧-八糖和2-去氧-庚糖,分别。