ProductName:LCMSGradeTFA(Trifluoroaceticacid)AlternativeNames:LCMSTFA;LCMSTFAAmps;TFAAmpules;Trifluoroaceticacid;TFAAcid;CAS#76-05-1;Perfluoricacid;2,2,2-Trifluoroaceticacid;HPLCTFA
Covachem"sLCMSGradeTrifluoroaceticacid(TFA)iswellsuitedasachromatographyadditivefordifficulttoseparateanalytesinHPLCandLCMSapplications.CovaChem"sLCMSTFAisanidealadditiveforseparationsofpeptidesinpeptidesynthesisapplications.Trifluoroaceticacidiswidelyusedtoseparatebothprotectedaminoacidchainsanddeprotectedpeptides.Duetotheaminoandcarboxylategroupshavingvastlydifferentpkavalues,syntheticpeptidescanbeparticularlychallengingtoseparate,TheHPLCseparationofpeptidesismuchmoreeasilyachievedwith0.1%Trifluoroaceticacidbeingpresentinthemobilephase.
Trifluoroaceticacid(TFA)istypicallybeneficialasaseparationsenhancer,andisamoderatelystrongionpairingagent,whichcanbeaveryeffectivewayofgaininggoodanalyteseparationandobtainingsharppeaksinHPLCapplications.AlthoughTFAisandexcellentlowpHbufferforHPLCapplications,thisionpairingeffecthassomenegativeimpactonionizationefficiencies(comparedtootheracidadditives,suchasFormicacid(CovaChem11202)andAceticacid(CovaChem11201.CovaChemoffersseveralremediesfortheimpactof0.1%TFAonionization,inservinghighlyrefinedproductsthatreversethiseffect.Thisreductionofionizationefficiencycanbeovercomebyincorporatingapost-columnadditionofa“TFAfix”reagent,suchasCovaChem"sUltraPure(2-(2-methoxyethoxy)ethanol(CovaChem11207)orLCMSGradePropionicacid(CovaChem11206).Theseproductsareeasytoemploy,andallowLCMStobeperformedonpeptidesandproteinswithoutalteringHPLCmethodsthatemploy0.1%TFA.Thesetfafixreagentshavesavedcountlesshoursofhplcmethoddevelopmentandvalidationhours.Pleasefeelfreetocontactourtechnicalsupportformoreinformationonthissubject.
CovaChem"sLCMSGradeTFAcomesintwoconvenientpackagesizes(10x1mLAmpulesand25mLbottles).The1mLAmpulesofLCMSGradeTFAareusefulforquicklypreparing1Literbottlesof0.1%TFAsolutionsineitherwaterorotherorganicsolvents.
ProductNumbers:11204-10x1or11204-25
Specifications
Appearance:Clearliquid
Purity:is≥99.5%
Storage:RoomTemperature
Properties
PhysicalState:Liquid
CAS#:76-05-1
ChemicalFormula:C2HF2O2
MolecularWeight:114.02amu
pKa:0.23
BoilingPoint:72.4°C(Lit)
Density:1.489g/mL
TariffCode:2915.90.5000
AdditionalProductInformation:
TrifluoroaceticAcid(TFA)ProductInformationBulletin
TrifluoroaceticAcid(TFA)MSDS
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第一类激素作用在靶细胞表面,并不进入细胞内部,而是与细胞膜表面特异的受体结合.这种结合使腺苷酸环化酶激活产生cAMP(一种第二信使),cAMP再去激活细胞内的一些特定系列的酶,从而引起各种生理效应.这是由E.W.Sutherland于1965年提出来的第二信使假说
第二类激素由于是脂溶性的小分子.能直接进入靶细胞,与靶细胞的细胞质中的受体分子结合成"激素-受体复合物",在一定条件下穿过核膜进入核内,与染色质上的一种酸性蛋白质相互作用,促进DNA样板转录相应的mRNA.
mRNA扩散出核膜进入细胞质,导致某种蛋白质(酶)的合成,从而引起这种激素的生理效应.
http://care.diabetesjournals.org/cgi/content/abstract/31/8/1479
OBJECTIVE—Hyperglycemiaisariskfactorformicrovascularcomplicationsandmayincreasetheriskofcardiovasculardiseaseinpatientswithtype2diabetes.ThisstudytestedtheLDLcholesterol–loweringagentcolesevelamHCl(colesevelam)asapotentialnoveltreatmentforimprovingglycemiccontrolinpatientswithtype2diabetesonsulfonylurea-basedtherapy.
RESEARCHDESIGNANDMETHODS—A26-week,randomized,double-blind,placebo-controlled,parallel-group,multicenterstudywascarriedoutbetweenAugust2004andAugust2006toevaluatetheefficacyandsafetyofcolesevelamforreducingA1Cinadultswithtype2diabeteswhoseglycemiccontrolwasinadequate(A1C7.5–9.5%)withexistingsulfonylureamonotherapyorsulfonylureaincombinationwithadditionaloralanti-diabetesagents.Intotal,461patientswererandomized(230givencolesevelam3.75g/dayand231givenplacebo).Theprimaryefficacymeasurementwasmeanplacebo-correctedchangeinA1Cfrombaselinetoweek26intheintent-to-treatpopulation(lastobservationcarriedforward).
RESULTS—Theleastsquares(LS)meanchangeinA1Cfrombaselinetoweek26was–0.32%inthecolesevelamgroupand+0.23%intheplacebogroup,resultinginatreatmentdifferenceof–0.54%(P<0.001).TheLSmeanpercentchangeinLDLcholesterolfrombaselinetoweek26was–16.1%inthecolesevelamgroupand+0.6%intheplacebogroup,resultinginatreatmentdifferenceof–16.7%(P<0.001).FurThermore,significantreductionsinfastingplasmaglucose,fructosamine,totalcholesterol,non–HDLcholesterol,andapolipoproteinBweredemonstratedinthecolesevelamrelativetoplacebogroupatweek26.
CONCLUSIONS—ColesevelamimprovedglycemiccontrolandreducedLDLcholesterollevelsinpatientswithtype2diabetesreceivingsulfonylurea-basedtherapy.
