Royer J C, Nakas J P
State University of New York, College of Environmental Science and Forestry, Syracuse 13210.
Eur J Biochem. 1991 Dec 5;202(2):521-9. doi: 10.1111/j.1432-1033.1991.tb16404.x.
Two endoxylanases were purified from the culture medium of Trichoderma longibrachiatum. Both enzymes were highly basic, and lacked activity on carboxymethyl-cellulose. An enzyme of 21.5 kDa (xylanase A) had a specific activity of 510 U/mg protein, a Km of 0.15 mg soluble xylan/ml, possessed transglycosidase activity and generated xylobiose and xylotriose as the major endproducts from xylan or xylose oligomers. A larger enzyme of 33 kDa (xylanase B) had a specific activity of 131 U/mg protein, a Km of 0.19 mg soluble xylan/ml, lacked detectable transglycosidase activity and generated xylobiose and xylose as major endproducts from xylan and xylose oligomers. Xylotriose was the smallest oligomer attacked by both enzymes. In addition, xylotriose inhibited hydrolysis of xylopentanose by both enzymes, while xylobiose appeared to inhibit xylanase B, but not xylanase A.
从长枝木霉的培养基中纯化出了两种内切木聚糖酶。这两种酶均具有高碱性，且对羧甲基纤维素无活性。一种21.5 kDa的酶（木聚糖酶A）的比活性为510 U/mg蛋白质，Km为0.15 mg可溶性木聚糖/ml，具有转糖苷酶活性，以木二糖和木三糖作为木聚糖或木糖寡聚物的主要终产物。一种较大的33 kDa的酶（木聚糖酶B）的比活性为131 U/mg蛋白质，Km为0.19 mg可溶性木聚糖/ml，未检测到转糖苷酶活性，以木二糖和木糖作为木聚糖和木糖寡聚物的主要终产物。木三糖是这两种酶作用的最小寡聚物。此外，木三糖抑制这两种酶对木戊糖的水解，而木二糖似乎抑制木聚糖酶B，但不抑制木聚糖酶A。
