Overview:
ZAK is a member of the MAPKKK family of signal transduction molecules and mediates gamma radiation signaling leading to cell cycle arrest. The activity of ZAK plays a role in cell cycle checkpoint regulation as well as being involved in regulating actin organization (1). Expression of kinase-dead ZAK in mouse fibroblasts disrupts actin stress fibers and causes morphologic changes. ZAK can activate JNK through MKK4/MKK7 and ERK5/p38-gamma via MKK3/MKK6. Expression of ZAK increases the population of cells in the G2/M phase of the cell cycle, whereas dominant-negative ZAK attenuated the G2 arrest caused by gamma radiation (2).
Gene Aliases:
AZK, MLT, MRK, MLK7, MLTK, mlklak, MAP3K20
Genbank Number:
NM_133646
References:
1. Yang J-J, et al: Mixed lineage kinase ZAK utilizing MKK7 and not MKK4 to activate the c-Jun N-terminal kinase and playing a role in the cell arrest. Biochem. Biophys. Res. Commun. 297: 105-110, 2002.2. Gross E. A, et al: MRK, a mixed lineage kinase-related molecule that plays a role in gamma-radiation-induced cell cycle arrest. J. Biol. Chem. 277: 13873-13882, 2002
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2、可逆抑制剂:包括
a、竞争性抑制剂,抑制剂与底物竞争性结合酶反应中心,使Km增大,而Vmax不变 b、非竞争性抑制剂,酶与抑制剂结合后还能与底物结合,但活性降低,使Vmax减小,而Km不变
c、反竞争性抑制剂,酶只能与底物结合后才能与抑制剂结合,Vmax与Km都减小
可逆抑制剂可用透析等方法除去,使酶恢复作用
1、测定酶比活力:底物需要过量么?测定时间多长?是否可以加入过量的底物,然后测定3min吸光度的增加值,从吸光度的变化值计算比活力。
2、在酶抑制剂筛选的过程中,是否需要保证底物过量?还是要水浴一定时间让反应完全?我看到文献说用终浓度为0.1μmol/mL的底物,终浓度为45U/ml的酶,我想问,假设总体积为1ml,那么终浓度为45U/ml的酶岂不是每分钟能转化4.8μmol的底物?那么0.1μmol/mL的底物不就几秒钟就反应完了?那么怎么测定初速度?
1.对于抑制剂筛选工作(求ic50)是不是体系内酶与底物的量(底物应该是过量的)对实验结果影响不大。
2.如果要求算Km值,是不是需要知道反应产物的绝对量。反应时间文献上都是5分钟,反应速度就用反应产物量除以反应时间即可。
3.酶是进口分装的,规格5U,一次用不完,用PBS稀释后如何保存
谢谢
《血管紧张素转换酶抑制剂在心血管病中应用的中国专家共识》.PDF(242.69k)
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