Romanowska Irena, Polak Jacek, Bielecki Stanisław
Institute of Technical Biochemistry, Technical University of Lodz, Stefanowskiego 4/10, 90-924 Lodz, Poland.
Appl Microbiol Biotechnol. 2006 Feb;69(6):665-71. doi: 10.1007/s00253-005-0011-0. Epub 2005 Jul 13.
Xylanase of low molecular weight (K II) was isolated from the fungus Aspergillus niger IBT-90 cultivated in medium with wheat bran. K II was purified by precipitation with ammonium sulphate (20-80% saturation) and gel filtration on Biogel P-10. This enzyme is most active in hydrolysis of birchwood xylan at 50 degrees C and pH 5.5. Xylanase K II has an ability to degrade 1,4-beta-bonds and to debranch substrates. It degrades not only xylans but also cellulose, an important factor for its application in bakery. Ag+, Fe3+ and NBS are strong inhibitors of the enzyme. DTT and Na+ activate xylanase K II by 24 and 13%, respectively. Enzyme K II used as additive to flour improves dough properties, increases the volume of wheat-rye and whole meal bread, and increases the porosity of crumb and the moisture of the final product, consequently extending the shelf life of bread.
低分子量木聚糖酶（K II）是从在含有麦麸的培养基中培养的黑曲霉IBT - 90中分离得到的。K II通过硫酸铵沉淀（20 - 80%饱和度）和在Biogel P - 10上进行凝胶过滤进行纯化。这种酶在50℃和pH 5.5时对桦木木聚糖的水解活性最高。木聚糖酶K II具有降解1,4 - β - 键和使底物去分支的能力。它不仅能降解木聚糖，还能降解纤维素，这是其在烘焙中应用的一个重要因素。Ag +、Fe3 +和N - 溴代琥珀酰亚胺是该酶的强抑制剂。二硫苏糖醇（DTT）和Na +分别使木聚糖酶K II的活性提高24%和13%。用作面粉添加剂的酶K II可改善面团特性，增加小麦黑麦面包和全麦面包的体积，并增加面包屑的孔隙率和最终产品的水分含量，从而延长面包的保质期。
