Kroon P A, Williamson G
Food Molecular Biochemistry Department, Institute of Food Research, Colney, Norwich, UK.
Biotechnol Appl Biochem. 1996 Jun;23(3):263-7.
Aspergillus niger cinnamoyl esterase (CinnAE) is shown to be active towards a wide range of feruloylated oligosaccharides derived from sugar-beet pulp (SBP). The esterase hydrolysed ferulic acid ester-linked to either C-2 of arabinose or C-6 of galactose residues, and demonstrated the highest activity towards the feruloylated arabinose trisaccharide. However, CinnAE was able to release only 0.88% of total alkali-extractable ferulic acid from SBP in 24 h when acting alone. To determine whether cell-wall-degrading enzymes could increase the release of ferulic acid by CinnAE, SBP was incubated with various carbohydrases [cellulase, polygalacturonase, endo-arabinanase, alpha-L-arabinofuranosidase, endo-(1,4-beta-D-galactanase, beta-D-galactosidase]. These were added alone and in pairs, both in the presence and absence of CinnAE. We showed that all the carbohydrases tested were free of esterase activity. When individual carbohydrases were incubated with SBP, whether in the presence or absence of CinnAE, less than 1% of the feruloyl groups were released. When incubated with a mixture of endo-arabinanase and alpha-L-arabinofuranosidase, the esterase was able to release 14 times more of the alkali-extractable ferulic acid present in the whole pulp as free acid than CinnAE alone. Ferulic acid is linked either to L-arabinose or D-galactose in SBP, but no corresponding increase in ferulic acid release was detected when SBP was incubated with CinnAE plus endo-(1,4)-beta-D-galactanase and beta-D-galactosidase (both from A. niger). Hence feruloylated arabinans in SBP are readily available for hydrolysis by arabinan-degrading enzymes, whereas feruloylated galactans are not available for hydrolysis by galactan-degrading enzymes.
黑曲霉肉桂酰酯酶（CinnAE）已被证明对多种源自甜菜粕（SBP）的阿魏酸酯化低聚糖具有活性。该酯酶能水解与阿拉伯糖的C - 2位或半乳糖残基的C - 6位相连的阿魏酸酯，并对阿魏酸酯化阿拉伯三糖表现出最高活性。然而，单独作用时，CinnAE在24小时内仅能从SBP中释放出0.88%的总碱可提取阿魏酸。为了确定细胞壁降解酶是否能增加CinnAE对阿魏酸的释放量，将SBP与多种碳水化合物酶[纤维素酶、多聚半乳糖醛酸酶、内切阿拉伯聚糖酶、α - L - 阿拉伯呋喃糖苷酶、内切 - （1,4） - β - D - 半乳聚糖酶、β - D - 半乳糖苷酶]一起孵育。这些酶单独添加以及成对添加，且均在有和没有CinnAE的情况下进行。我们发现所有测试的碳水化合物酶都没有酯酶活性。当单独的碳水化合物酶与SBP孵育时，无论有无CinnAE，释放的阿魏酰基都不到1%。当与内切阿拉伯聚糖酶和α - L - 阿拉伯呋喃糖苷酶的混合物一起孵育时，该酯酶作为游离酸从整个果肉中释放出的碱可提取阿魏酸比单独的CinnAE多14倍。在SBP中，阿魏酸与L - 阿拉伯糖或D - 半乳糖相连，但当SBP与CinnAE加上内切 - （1,4） - β - D - 半乳聚糖酶和β - D - 半乳糖苷酶（均来自黑曲霉）一起孵育时，未检测到阿魏酸释放量有相应增加。因此，SBP中的阿魏酸酯化阿拉伯聚糖很容易被阿拉伯聚糖降解酶水解，而阿魏酸酯化半乳聚糖则不能被半乳聚糖降解酶水解。
