摘要
经超滤浓缩、分子筛色谱、阴离子和阳离子交换层析 ,由棘孢曲霉发酵液最终分离得到 4个电泳纯的木聚糖酶主要组分Xy 1、Xy 2、Xy 3和Xy 4。通过SDS 聚丙烯酰胺凝胶电泳测得各组分的分子量分别是 92 1 3、32 4 0、4 2 4 0和 2 7 0 3kD。实验证明这些酶组分均属于酸性木聚糖酶 ,Xy 1、Xy 2、Xy 3和Xy 4的最适反应pH分别为 5 0、4 0、4 6和 3～ 3 5。各酶组分在酸性条件下较稳定 ,碱性条件下酶活丧失较快。Xy 1及Xy 2的最适反应温度在75℃ ,在 5 0℃以下比较稳定 ;Xy 3及Xy 4最适反应温度为 5 5℃ ,在 4 0℃以下比较稳定。通过对各酶组分米氏常数的测定可知 ,Xy 1及Xy 2对底物桦木木聚糖的Km 值分别为 0 36 %和 0 2 6 % ,Xy 3及Xy 4的Km 值为 2 4 6 %和1 3 9%。 4种组分的Vmax 分别为 4 0 1 μmol min mg、8 81 μmol min mg、81 97μmol min mg、4 71 μmol min mg。Cu2 + 、Ag+对各组分都有较强的抑制作用 ,Mg2 + 、Ba2 + 、Ca2 + 能促进Xy 3的木聚糖酶活 ,Ca2 + 也可大幅度促进Xy 4的木聚糖酶活性。
Four components of xylanases were separated and purified by using exclusion chromatography and ion-exchange chromatography and other purification methods from the Aspergillus aculeatus SM-L22 The molecular weights of each components were characterized by SDS-PAGE, and were 92 13 kD,32 4 kD,42 4 kD,27 03 kD, respectively. The optimal pHs for the four xylanases were 5 0, 4 0, 4 6 and 3～3 5 respectively, and all four were stable in acidic or neutral condition. The optimum temperatures for Xy-1 and Xy-2 were the same to be 75℃, and they showed good stability at 50℃. Xy-3 and Xy-4 had lower optimum temperatures being 55℃, and they were stable only below 40℃. The K m values of Xy-1, Xy-2, Xy-3 and Xy-4 were 0 36%, 0 26%, 2 46% and 13 9% respectively, when the xylan from beachwood was as substrate, and the V max values of these activities were 4 01μmol/min/mg, 8 81μmol/min/mg, 81 97μmol/min/mg, 4 71μmol/min/mg, respectively. The activity of each component can be strongly inhibited by Cu 2+ and Ag +. The activities of Xy-3 can be increased dramatically by Mg 2+, Ba 2+, Ca 2+. The activity of Xy-4 can also be increased by Ca 2+.
出处
《微生物学报》
CAS
CSCD
北大核心
2004年第3期351-355,共5页
Acta Microbiologica Sinica
基金
国家自然科学基金资助项目 ( 3 0 0 70 0 2 2和 3 0 170 0 2 8)~~
关键词
棘孢曲霉
木聚糖酶
分离纯化
基本性质
Aspergillus aculeatus, Xylanase, Isolation and Purification, Characters
