Laboratory of Food Chemistry, Wageningen University, Bomenweg 2, 6703 HD Wageningen, The Netherlands.
Bioresour Technol. 2011 Jan;102(2):1636-43. doi: 10.1016/j.biortech.2010.09.029. Epub 2010 Sep 22.
The mode of action of four Chrysosporium lucknowense C1 α-L-arabinohydrolases was determined to enable controlled and effective degradation of arabinan. The active site of endoarabinanase Abn1 has at least six subsites, of which the subsites -1 to +2 have to be occupied for hydrolysis. Abn1 was able to hydrolyze a branched arabinohexaose with a double substituted arabinose at subsite -2. The exo acting enzymes Abn2, Abn4 and Abf3 release arabinobiose (Abn2) and arabinose (Abn4 and Abf3) from the non-reducing end of reduced arabinose oligomers. Abn2 binds the two arabinose units only at the subsites -1 and -2. Abf3 prefers small oligomers over large oligomers. It is able to hydrolyze all linkages present in beet arabinan, including the linkages of double substituted residues. Abn4 is more active towards polymeric substrate and releases arabinose monomers from single substituted arabinose residues. Depending on the combination of the enzymes, the C1 arabinohydrolases can be used to effectively release branched arabinose oligomers and/or arabinose monomers.
为了实现阿拉伯聚糖的可控有效降解，我们确定了四种耻垢菌素 lucknowense C1α-L-阿拉伯水解酶的作用模式。内切阿拉伯聚糖酶 Abn1 的活性位点至少有六个亚位点，水解需要占据亚位点-1 到+2。Abn1 能够水解带有双取代阿拉伯糖的支化阿拉伯六糖，在亚位点-2 上发生双取代。外切作用的酶 Abn2、Abn4 和 Abf3 从还原阿拉伯寡糖的非还原端释放阿拉伯二糖（Abn2）和阿拉伯糖（Abn4 和 Abf3）。Abn2 仅在亚位点-1 和-2 上结合两个阿拉伯糖单元。Abf3 更喜欢小的寡糖而不是大的寡糖。它能够水解所有存在于甜菜阿拉伯聚糖中的键，包括双取代残基的键。Abn4 对聚合底物更活跃，从单取代阿拉伯糖残基释放阿拉伯糖单体。根据酶的组合，C1 阿拉伯水解酶可用于有效释放支化阿拉伯寡糖和/或阿拉伯糖单体。
