顶青霉木聚糖酶的水解动力学与水解模式

从顶青霉（Penicillium corylophilum）培养液中分离纯化得到的3种木聚糖酶组分(Part A,Part B和Part C)，对其水解动力学和水解模式的研究结果表明,3种木聚糖酶的动力学常数（桦木木聚糖为底物）分别为Part A,K

Dynamics and Modes of Action of Xylanases fromPenicillium corylophilum on Xylan

Dynamics and mode of acting on xylan of three parts of xylanases (Part A, Part B and Part C) separated and purified from a culture filtrate of Penicillium corylophilum No. P-3-31 were investigated. The Km and Vmax of the three purified enzymes with birchwood xylan as a substrate were 1.00 mg/mL and 0.159 U/mL for Part A ( pH 4.0, 50 ℃) , 1.59 mg/mL and 0.274 U/mL for Part B (pH 4.0,50 ℃) and 0.85 mg/mL and 0.200 U/mL for Part C (pH 5.5,50 ℃). Based on the dynamic studies, it was deduced that three purified enzymes had the same mode of action on xylan. Xylotriose and xylobiose were main hydrolysates of long-chain xylan by these enzymes. Xylooligosaccharides upwards from xylotetraose were immediately hydrolyzed, and xylotetraose was mainly hydrolyzed to xylobiose. Xylotriose was slowly hydrolyzed, but xylobiose was unable to be further hydrolyzed by these enzymes. The studies on the hydrolysis dynamics of xylan from corncob with crude enzyme showed that the hydrolysis of arabinose side-chain was almost simultaneous with the hydrolysis of xylan, therefore it could be concluded that there existed a α-L-arabinofuranosidase in crude enzyme.