Characterization of jack-bean alpha-D-mannosidase as a zinc metalloenzyme.
Characterization of jack-bean alpha-D-mannosidase as a zinc metalloenzyme.
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刀豆 α-D-甘露糖苷酶作为锌金属酶的表征。
DOI：
10.1042/bj1470083
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发表时间：
1975
影响因子：
4.1
通讯作者：
S. M. Snaith
中科院分区：
文献类型：
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作者：
S. M. Snaith
1.使用两种方法来获得不含未结合的Zn 2+的α-甘露糖苷酶，（a）通过从在Zn 2+存在下纯化的制剂中除去过量的金属离子，和（B）通过在不需要添加Zn 2+的条件下纯化。2.纯化的酶经超离心、聚丙烯酰胺凝胶电泳和凝胶层析均为均一的。3.分子量估计为230 000。4.该酶含有470至565 μ g/g蛋白质的锌，对应于1.7至2个锌原子/酶分子。其他金属的含量要低得多。5.螯合剂可使酶失活，Zn 2+可使酶活性恢复。6.没有发现其他金属离子取代Zn ~（2+）而保持活性。某些二价金属离子，如Cu 2+，能迅速地使酶失活。7.结果表明，杰克豆α-甘露糖苷酶天然存在的锌蛋白复合物，可以被认为是一种金属酶。
1. Two methods were used to obtain alpha-mannosidase free from unbound Zn2+, (a) by removal of excess of metal ion from preparations purified in the presence of Zn2+ and (b) by purification under conditions that eliminate the need to add Zn2+. 2. The purified enzyme is homogeneous on ultracentrifugation, polyacrylamide-gel electrophoresis and gel chromatography. 3. The molecular weight is estimated to be 230 000. 4. The enzyme contains between 470 and 565 mug of zinc/g of protein, corresponding to between 1.7 and 2 atoms of zinc/enzyme molecule. The contents of other metals are much lower. 5. The enzyme is inactivated by chelating agents and activity is restored by Zn2+. 6. No other metal ion was found to replace Zn2+ with retention of activity. Some bivalent metal ions, e.g. Cu2+, rapidly inactivate the enzyme. 7. The results indicate that jack-bean alpha-mannosidase exists naturally as a zinc-protein complex and may be considered as a metalloenzyme.