Akiba S, Yamamoto K, Kumagai H
Biological Science Laboratories, Kao Corporation, Ibaraki, Japan.
Biosci Biotechnol Biochem. 1998 Nov;62(11):2171-6. doi: 10.1271/bbb.62.2171.
Three different carbohydrate-depleted enzymes were prepared from an endo-beta-1,4-glucanase of Aspergillus niger IFO31125 by treatment with endo-beta-N-acetylglucosaminidase or alpha-mannosidase. The molecular sizes of these enzymes decreased from 40 kDa containing about 8.9% carbohydrate to 39, 38, and 37 kDa with carbohydrate at 4.5, 1.3, and 0.8% (w/w), respectively. The surface net charges on these enzyme preparations were calculated from their electrophoretic mobilities measured by capillary zone electrophoresis. They had increased negative charges corresponding to the decreases in the carbohydrate content; those of native and 37-kDa enzymes were about -0.03 and -0.045, respectively. The surface hydrophobicities of proteins were also measured by partitioning the enzymes in a two-phase system containing polyethylene glycol and dextran, and decreased corresponding with decreases in their carbohydrate content. The results indicated that the high mannose type of carbohydrate chain in endo-beta-1,4-glucanase affected the surface net charge on the enzyme and increased the surface hydrophobicity.
通过用内切β-N-乙酰氨基葡萄糖苷酶或α-甘露糖苷酶处理黑曲霉IFO31125的内切β-1,4-葡聚糖酶，制备了三种不同的碳水化合物缺失型酶。这些酶的分子大小从含有约8.9%碳水化合物的40 kDa分别降至碳水化合物含量为4.5%、1.3%和0.8%（w/w）的39 kDa、38 kDa和37 kDa。根据通过毛细管区带电泳测量的电泳迁移率计算这些酶制剂的表面净电荷。它们的负电荷增加，这与碳水化合物含量的降低相对应；天然酶和37 kDa酶的表面净电荷分别约为-0.03和-0.045。还通过将酶分配到含有聚乙二醇和葡聚糖的两相系统中来测量蛋白质的表面疏水性，其随着碳水化合物含量的降低而降低。结果表明，内切β-1,4-葡聚糖酶中的高甘露糖型碳水化合物链影响了酶的表面净电荷并增加了表面疏水性。
