顶青霉木聚糖酶的纯化与性质

从顶青霉(Pencilliumcorylophilum)P-3-31培养液中分离到3种木聚糖酶组分，分别称为PartA、PartB和PartC.PartB进一步纯化，经SDS-PAGE鉴定为单带，相对分子质量为24200；PartC进一步纯化，经SDS-PAGE鉴定也是单带，相对分子质量为48300.PartA和PartB的最适反应条件为pH4.0,45℃;PartC的最适反应条件为pH5.5,55℃.PartA和PartB对木聚糖以外的底物不能水解；PartC具有水解CMC的交叉活性和β-木糖苷酶活性，但不能将木二糖水解成木糖.3个纯化酶组分和粗酶对不同来源的木聚糖底物均表现出不同的活性.对于粗酶，若桦木木聚糖为底物的相对酶活为100%，则玉米芯木聚糖为底物的相对酶活为143%，蔗渣木聚糖为底物的相对酶活为124%.

Purification andProperties of Xylanases from Pencillium corylophilum

Three parts of xylanases (Part A, Part B and Part C) wereseparated and purified from a culture filtrate of Pencillium corylophilum No.P-3-31. Part B was further purified to homogeneity and Part C was further purified to almost homogeneity by the same procedures as Part B. The molecular weights of Part B and Part C were estimated to be 24 200 and 48 300 respectively by SDS-PAGE. The optimal pH and temperature of enzymes were 4.0 and 45 ℃ for Part A and Part B, while 5.5 and 50～55 ℃ for Part C. Part C showed a substrate-cross- specificity on hydrolyzing CMC and had an activity of β-xylosidase, but this activity was unable to hydrolyze xylobiose. Part A and Part B did not show the substrate-cross-specificity. Both crude and purified enzymes showed significant differences in their activities to hydrolyze different xylans from different sources. For the crude enzyme, if the activity to birchwood xylan was set as 100%, then those to corncob xylan and bagasse xylan were 143% and 124% respectively.