酶的粗制品分离常用方法是（）
A.吸附分离法
B.盐析法
C.有机溶剂沉淀法
D.层析法
E.等电沉淀法
参考答案：A
解析：酶蛋白分离纯化方法包括盐析法、有机溶剂沉淀法、吸附分离法、层析法、电泳法、结晶法等。其中盐析法是最常用方法，无变性作用，易透析脱盐；有机溶剂沉淀法分辨率高，不需脱盐，但易失活，需低温操作；吸附分离法可去杂质并浓缩酶，常用于酶的粗制品分离；电泳法可用于分析和制备，并可测酶蛋白的等电点，需防失活；结晶法得到的结晶酶易保存，但不一定是完全纯化品。
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| As I had my first child, I promised myself never to be a push parent. I was going to be a very 1 and understanding mother. Five years later my little boy was about to 2 for his yellow belt in karate (空手道 ). As a five-year-old child, he wasn't taking it 3 , because it was mom trying to help him. I found myself yelling and telling him he would never get the belt acting like that. I was trying to 4 him his back-flip. He 5 to play and I continued to yell. Finally I had made him feel like he couldn't 6 anything, just as I promised myself I wouldn't do. Still mad and stubborn I couldn't 7 . I had to teach him this flip. He was doing fine with it by the time we had to leave to go to karate. While taking the test, he did great. His 8 would ask him to do something, and it became 9 for him. He never asked him to do the back-flip. He had passed his yellow belt test. We got into the car to 10 when he looked at me and said “Mom, why did you make me do that back-flip so many times, 11 it wasn't even on the test.” The words wouldn't have 12 anything to anyone else, but it was a 13 in my face. That night while lying in bed, I told him I loved him. He was 14 and didn't say anything, just giggled. I said, “I really do love you baby.” I was still feeling 15 and also 16 if he had forgiven me. Finally he replied in the 17 voice, “I know you do, but I love you more.” He had forgiven me and I had decided that his feelings were more 18 than any test he would ever take. I made a new 19 to be a better mother and to 20 that he was only a child. | |||
| ( )1. A. patient ( )2. A. look ( )3. A. easy ( )4. A. help ( )5. A. started ( )6. A. accomplish ( )7. A. give up ( )8. A. father ( )9. A. quick ( )10. A. go home ( )11. A. when ( )12. A. expected ( )13. A. wind ( )14. A. working ( )15. A. guilty ( )16. A. knowing ( )17. A. saddest ( )18. A. true ( )19. A. promise ( )20. A. accept | B. good B. practise B. happily B. teach B. kept on B. feel B. give in B. teacher B. normal B. go shopping B. once B. reached B. moment B. moving B. happy B. puzzling B. sweetest B. sincere B. gift B. help | C. polite C. play C. seriously C. make C. continued C. try C. give away C. doctor C. common C. rest ourselves C. while C. demanded C. smile C. playing C. upset C. wondering C. happiest C. faithful C. plan C. know | D. affectionate D. test D. fairly D. tell D. prevented D. pass D. give out D. instructor D. natural D. enjoy ourselves D. if D. meant D. slap D. crying D. stubborn D. believing D. biggest D. important D. experiment D. agree |