Enzymatic Synthesis of Functional Oligosaccharides from Lactulose.

乳果糖已经获得了广泛的用途；双歧杆菌在维持婴儿和成人正常肠道菌群中的作用，减少脑病复发的频率，并允许在绝大多数此类患者中增加饮食蛋白质消耗，不太明确的氮性门脉-系统性脑病严重恶化。本文报道了米曲霉-半乳糖苷酶催化乳果糖转半乳糖基化反应形成的低聚糖的分离和性质。主要的三糖、四糖和五糖通过炭柱和制备纸层析分离得到，结构为：O- - d -半乳糖-(1—6)-O- - d -半乳糖-吡喃基-(1—4)-果糖（TR）、O- - d -半乳糖-(1—6)-O- - d -半乳糖-(1—6)-O- - d -半乳糖-(1—4)-果糖（TE）和O- - d -半乳糖-(1—6)-O- - d -半乳糖-(1—6)-O- - d -半乳糖-(1—6)-O- - d -半乳糖-(1—4)- d -果糖（PE）。为了在含乳糖的培养基中生产低聚糖，从25种曲霉和24种米曲霉中筛选出的米曲霉S-65从乳糖中积累了大量的半乳低聚糖。形成的寡糖含量最多的是TR和TE。laurentii隐球菌在含有乳糖的培养基中也能产生低聚糖。根据总糖，三糖的产率为15.5%。形成的主要产物是一种迄今尚未描述的三糖，O- - d -半乳糖酰基-(1—4)-O- - d -半乳糖酰基-(1—4)- d -果糖。

Lactulose has acquired a broad range of usefulness; bifidus factor in maintaining the normal intestinal microflora of infant and also adult, reduction the frequency of recurrences of encephalophthy and permits increased dietary protein consumption in the great majority of such patients, less well defined severe exacerbations of nitrogenous portal-systemic encephalopathy.In this report, isolation and characterization of oligosaccharides formed by the transgalactosylation reaction of lactulose catalyzed by Aspergillus oryzae -galactosidase were described. Major Tri-, tetra- and pentasaccharide has been isolated by charcoal column and preparative paper chromatography and shown to have the structure: O- -D-galactopyranosyl-(1---6)-O- -D-galacto-pyranosyl-(1---4)-D-fructose(TR), O- -D-galactopyranosyl-(1---6)-O- -D-galacto-pyranosyl-(1---6)-O- -D-galactopyranosyl-(1---4)-D-fructose(TE), and O- -D-galactopyranosyl-(1---6)-O- -D-galactopylanosyl-(1---6)-O- -D-galactopyranosyl-(1---6)-O- -D-galactopyranosyl-(1---4)-D-fructose(PE).In attempt to produce oligosaccharides in medium containing lacturose, an Aspergillus oryzae S-65 screened from 25 aspergillus species and 24 Aspergillus oryzae strains accumulate in large quantities of galacto oligosaccharides from lactulose. The most abundant oligosaccharide formed were TR and TE. A Cryptococcus laurentii also produced oligosaccharides in lacturose containing medium. The yield of trisaccharides was 15.5 per cent based on total saccharides. The main product formed was A hitherto undescrided trisaccharide, O- -D-galactopyranosyl-(1---4)-O- -D-galactopyranosyl-(1---4)-D-fructose.