Wood T M, McCrae S I, Bhat K M
Rowett Research Institute, Bucksburn, Aberdeen, Scotland, U.K.
Biochem J. 1989 May 15;260(1):37-43. doi: 10.1042/bj2600037.
Studies on reconstituted mixtures of extensively purified cellobiohydrolases I and II and the five major endoglucanases of the fungus Penicillium pinophilum have provided some new information on the mechanism by which crystalline cellulose in the form of the cotton fibre is rendered soluble. It was observed that there was little or no synergistic activity either between purified cellobiohydrolases I and II, or, contrary to previous findings, between the individual cellobiohydrolases and the endoglucanases. Cotton fibre was degraded to a significant degree only when three enzymes were present in the reconstituted enzyme mixture: these were cellobiohydrolases I and II and some specific endoglucanases. The optimum ratio of the cellobiohydrolases was 1:1. Only a trace of endoglucanase activity was required to make the mixture of cellobiohydrolases I and II effective. The addition of cellobiohydrolases I and II individually to endoglucanases from other cellulolytic fungi resulted in little synergistic activity; however, a mixture of endoglucanases and both cellobiohydrolases was effective. It is suggested that current concepts of the mechanism of cellulase action may be the result of incompletely resolved complexes between cellobiohydrolase and endoglucanase activities. It was found that such complexes in filtrates of P. pinophilium or Trichoderma reesei were easily resolved using affinity chromatography on a column of p-aminobenzyl-1-thio-beta-D-cellobioside.
对嗜松青霉中经过广泛纯化的纤维二糖水解酶I和II以及五种主要内切葡聚糖酶的重组混合物进行的研究，为棉纤维形式的结晶纤维素变得可溶的机制提供了一些新信息。据观察，纯化的纤维二糖水解酶I和II之间几乎没有协同活性，或者与之前的发现相反，在单个纤维二糖水解酶和内切葡聚糖酶之间也几乎没有协同活性。只有当重组酶混合物中存在三种酶时，棉纤维才会有显著程度的降解：这三种酶是纤维二糖水解酶I和II以及一些特定的内切葡聚糖酶。纤维二糖水解酶的最佳比例为1:1。只需要微量的内切葡聚糖酶活性就能使纤维二糖水解酶I和II的混合物发挥作用。将纤维二糖水解酶I和II分别添加到来自其他纤维素分解真菌的内切葡聚糖酶中，几乎没有协同活性；然而，内切葡聚糖酶和两种纤维二糖水解酶的混合物是有效的。有人认为，目前关于纤维素酶作用机制的概念可能是纤维二糖水解酶和内切葡聚糖酶活性之间未完全解析的复合物的结果。研究发现，使用对氨基苄基-1-硫代-β-D-纤维二糖苷柱进行亲和色谱法，可以轻松解析嗜松青霉或里氏木霉滤液中的此类复合物。
