LimaBeanInhibitor:Limabeantrypsininhibitorwhichinhibitsbovineaswellashumantrypsinandplasmin,actsuponbothtrypsinandchymotrypsinbyformingequimolarcomplexes.Limabeaninhibitorsmaybechromatographicallyseparatedintoasmanyassixvariants.Jonesetal.,Biochem.,2,66,(1963)characterizedfourofthem.Allhavesimilarbutnotidenticalaminoacidcomposition,containsixorsevendisulfidebondsandlackmethionineandtryptophan.Molecularweightsvarybetween8kDaand10kDa.
StABIlity/Storage:Thelimabeaninhibitorisstable1-2yearsat2-8°C.
Ovomucoid:Ovomucoidsaretheglycoproteinproteaseinhibitorsofavianeggwhite.Thereareseveralproteaseinhibitorsineggwhite.TheWorthingtonproductisthatdescribedbyLineweaverandMurrayJBC,171,565(1947).Ithasamolecularweightofapproximately28kDa.
Stability/Storage:Ovomucoidisstable1-2yearswhenstoredat2-8°C.
PancreaticInhibitor:ThepancreaticinhibitorproducedbyWorthingtonisoftenreferredtoastheKunitzinhibitorandwasfirstcrystallizedbyKunitzandNorthropJ.Gen.Physiol.,19,991(1936).Itformsaverystable1:1complexwithbovinetrypsinbetweenpH3and10andalsowithhumantrypsins.Chymotrypsinisalsoinhibitedbythisproductbutisboundlesstightly.Theesterolytic,proteolyticandelastolyticactivitiesofporcineelastase,ontheotherhand,arenotinhibited.TheKunitzinhibitorisasinglepolypeptidechainof58aminoacidsandhasamolecularweightof6.5kDa.Whenlungtissueisusedasthesource,theinhibitoriscalledaprotinin.
Stability/Storage:Thepancreaticinhibitorisstable1-2yearswhenstoredat2-8°C.
SoybeanInhibitor:ThesoybeantrypsininhibitorwasfirstcrystallizedbyKunitzin1945andisoneofseveralsuchinhibitorsfoundinsoybeans.Itsmolecularweightis21,500±800daltonsandtheoptimumpHis7.0.Soybeaninhibitorinhibitstrypsinmole-for-moleandtoalesserextentchymotrypsin.
Stability/Storage:Thesoybeaninhibitorisstablefor1-2yearsat2-8°C.
UnitDefinition:Theactivityoftheinhibitorsisexpressedastheamountoftwicecrystallizedtrypsin(WorthingtonCode:TRL)inhibitedpermilligramofinhibitor.1mgTRL≥180TAMEunits,10,350BAEEunits,3,450USP/NFunits.
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NeutralProtease(Dispase,NPRO)
Papain(PAP/PAPL/PAP2)
ProteinaseK(PROK)
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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？
《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)
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
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
