PurchasehighpurityCeralpha:α-AmylaseReagent–4vialsforthemeasurementofα-amylaseforresearch,biochemicalenzymeassaysandinvitrodiagnosticanalysis.
Measurementofα-amylaseactivityinwhitewheatflour,milledmalt,andmicrobialenzymepreparations,usingtheceralphaassay:Collaborativestudy.
McCleary,B.V.,McNally,M.,Monaghan,D.&Mugford,D.C.(2002).JournalofAOACInternational,85(5),1096-1102.
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Thisstudywasconductedtoevaluatethemethodperformanceofarapidprocedureforthemeasurementofα-amylaseactivityinfloursandmicrobialenzymepreparations.Samplesweremilled(ifnecessary)topassa0.5mmsieveandthenextractedwithabuffer/saltsolution,andtheextractswereclarifiedanddiluted.Aliquotsofdilutedextract(containingα-amylase)wereincubatedwithsubstratemixtureunderdefinedconditionsofpH,temperature,andtime.Thesubstrateusedwasnonreducingend-blocked
p-nitrophenylmaltoheptaoside(BPNPG7)inthepresenceofexcessquantitiesof
Thermostableα-glucosidase.TheblockinggroupinBPNPG7preventshydrolysisofthissubstrateby
exo-actingenzymessuchasamyloglucosidase,α-glucosidase,andβ-amylase.Whenthesubstrateiscleavedbyendo-actingα-amylase,thenitrophenyloligosaccharideisimmediatelyandcompletelyhydrolyzedto
p-nitrophenolandfreeglucosebytheexcessquantitiesofα-glucosidasepresentinthesubstratemixture.Thereactionisterminated,andthephenolatecolordevelopedbytheadditionofanalkalinesolutionismeasuredat400nm.AmylaseactivityisexpressedintermsofCeralphaunits;1unitisdefinedastheamountofenzymerequiredtorelease1µmol
p-nitrophenyl(inthepresenceofexcessquantitiesofα-glucosidase)in1minat40°C.Inthepresentstudy,15laboratoriesanalyzed16samplesasblindduplicates.Theanalyzedsampleswerewhitewheatflour,whitewheatflourtowhichfungalα-amylasehadbeenadded,milledmalt,andfungalandbacterialenzymepreparations.Repeat
ABIlityrelativestandarddeviationsrangedfrom1.4to14.4%,andreproducibilityrelativestandarddeviationsrangedfrom5.0to16.7%.
Theeffectofcarbohydratesonα-amylaseactivitymeasurements.
Baks,T.,Janssen,A.E.&Boom,R.M.(2006).EnzymeandMicrobialTechnology,39(1),114-119.
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TheCeralphamethodcanbeusedforα-amylaseactivitymeasurementsduringthehydrolysisofstarchathighsubstrateconcentrations(>40wt.%).However,theresultsareaffectedbythecarbohydratespresentinthesamples.TheeffectofcarbohydratesontheCeralphaα-amylaseactivitymeasurementswasmeasuredoverabroadconcentrationrange.ItwasfoundthatstarchhasthelargestinfluenceandglucosehasthelowestinfluenceontheCeralphaassayprocedure.Theseresultswereexplainedbyconsideringsubstrateinhibitionandsubstratecompetition.Asimplekineticmodelwasusedtodescribetheobservedphenomenaquantitatively.ThismodelwasalsousedtoestimatetheMichaelis–MentenconstantforalargenumberofsubstratesanditrequiresonlyasingleexperimentforeachKmdetermination.
Cross-inhibitoryactivityofcerealproteininhibitorsagainstα-amylasesandxylanases.
Sancho,A.I.,Faulds,C.B.,Svensson,B.,Bartolomé,B.,Williamson,G.&Juge,N.(2003).BiochimicaetBiophysicaActa(BBA)-ProteinsandProteomics,1650(1),136-144.
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Thepurificationandcharacterisationofaxylanaseinhibitor(XIP-I)fromwheatwasreportedpreviously.Inourcurrentwork,XIP-Iisalsodemonstratedtohavethecapacitytoinhibitthetwobarleyα-amylaseisozymes(AMY1andAMY2).XIP-IcompletelyinhibitedtheactivityofAMY1andAMY2towardsinsolubleBlueStarchandasolublehepta-oligosaccharidederivative.Aternarycomplexwasformedbetweeninsolublestarch,acatalyticallyinactivemutantofAMY1(D180A),andXIP-I,suggestingthatthesubstrate–XIP-Iinteractionisnecessaryforinhibitionofbarleyα-amylases.Kivaluesforα-amylaseinhibition,however,couldnotbecalculatedduetothenonlinearnatureoftheinhibitionpattern.Furthermore,surfaceplasmonresonanceandgelelectrophoresisdidnotindicateinteractionbetweenXIP-Iandtheα-amylases.TheinhibitionwasabolishedbyCaCl2,indicatingthatthedrivingforcefortheinteractionisdifferentfromthatofcomplexationbetweenthebarleyα-amylase/subtilisininhibitor(BASI)andAMY2.ThisisthefirstreportofaproteinaceousinhibitorofAMY1.BASI,inaddition,wasdemonstratedtopartiallyinhibittheendo-1,4-β-D-xylanasefromAspergillusniger(XylA)ofglycosidehydrolasefamily11.Takentogether,thedatademonstrateforthefirsttimethedualtargetenzymespecificityofBASIandXIP-Iinhibitorsforxylanaseandα-amylase.
OverexpressionoftheArabidopsissyntaxinPEP12/SYP21inhibitstransportfromtheprevacuolarcompartmenttothelyticvacuoleinvivo.
Foresti,O.,daSilva,L.L.P.&Denecke,J.(2006).ThePlantCell,18(9),2275-2293.
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Golgi-mediatedtransporttothelyticvacuoleinvolvespassagethroughtheprevacuolarcompartment(PVC),butlittleisknownabouthowvacuolarproteinsexitthePVC.Weshowthatthislaststepisinhibitedbyoverexpressionof
ArabidopsisthalianasyntaxinPEP12/SYP21,causinganaccumulationofsolubleandmembranecargoandtheplantvacuolarsortingreceptorBP80inthePVC.AnterogradetransportproceedsnormallyfromtheendoplasmicreticulumtotheGolgiandthePVC,althoughexportfromthePVCappearstobecompromised,affectingbothanterogrademembraneflowtothevacuoleandtherecyclingrouteofBP80totheGolgi.However,Golgi-mediatedtransportofsolubleandmembranecargotowardtheplasmamembraneisnotaffected,butasolubleBP80ligandispartiallymis-sortedtotheculturemedium.WealsoobserveclusteringofindividualPVCbodiesthatmovetogetherandposs
IBLyfusewitheachother,formingenlargedcompartments.WeconcludethatPEP12/SYP21overexpressionspecificallyinhibitsexportfromthePVCwithoutaffectingtheGolgicomplexorcompromisingthesecretorybranchoftheendomembranesystem.TheresultsprovideafunctionalinvivoassaythatconfirmsPEP12/SYP21involvementinvacuolarsortingandindicatesthatexcessofthissyntaxininthePVCcanbedetrimentalforfurthertransportfromthisorganelle.
Vacuolartransportintobaccoleafepidermiscellsinvolvesasinglerouteforsolublecargoandmultipleroutesformembranecargo.
Bottanelli,F.,Foresti,O.,Hanton,S.&Denecke,J.(2011).ThePlantCell,23(8),3007-3025.
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Wetestedifdifferentclassesofvacuolarcargoreachthevacuoleviadistinctmechanismsbyinterferenceatmultiplestepsalongthetransportroute.Weshowthatnucleotide-freemutantsoflowmolecularweightGTPases,includingRab11,theRab5membersRha1andAra6,andthetonoplast-residentRab7,causedinducedsecretionofbothlyticandstoragevacuolarcargo.InsituanalysisinleafepidermiscellsindicatesasequentialactionofRab11,Rab5,andRab7GTPases.ComparedwithRab5members,mutantRab11mediatesanearlytransportdefectinterferingwiththearrivalofcargoatprevacuoles,whilemutantRab7inhibitsthefinaldeliverytothevacuoleandincreasescargolevelsinprevacuoles.Incontrastwithsolublecargo,membranecargomayfollowdifferentroutes.Tonoplasttargetingofanα-TIPchimerawasimpairedbynucleotide-freeRha1,Ara6,andRab7similartosolublecargo.Bycontrast,thetail-anchoredtonoplastSNAREVam3sharesonlytheRab7-mediatedvacuolardepositionstep.ThemostmarkeddifferencewasobservedforthecalcineurinbindingproteinCBL6,whichwasinsensitivetoallRabmutantstested.Unlikesolublecargo,α-TIPandVam3,CBL6transporttothevacuolewasCOPIIindependent.Theresultsindicatethatsolublevacuolarproteinsfollowasingleroutetovacuoles,whilemembranespanningproteinsmayuseatleastthreedifferenttransportmechanisms.
Measurementofα-amylaseactivitybySequentialInjectionAnalysis.
Min,R.W.,Carlsen,M.,Nielsen,J.&Villadsen,J.(1995).BiotechnologyTechniques,9(10),763-766.
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ASequentialInjectionAnalysis(SIA)systemformonitoringα-amylaseactivityisdescribed.TheSIAanalyserisafurtherdevelopmentofpreviouslyinvestigatedFlowInjectionAnalysis(FIA)analyser.Theanalysisofα-amylaseactivityisbasedonmonitoringthedecolorationofaniodine-starchcomplex.PerformancesoftheSIAanalyserhavebeencomparedwiththeFIAanalyser.AgoodagreementhasbeenobtainedbetweentheSIAmeasurementsandtheFIAmeasurements.
Secretion,purification,andcharacterisationofbarleyα-amylaseproducedbyheterologousgeneexpressioninAspergillusniger.
Juge,N.,Svensson,B.&Williamson,G.(1998).
AppliedMicroBIOLOGyandBiotechnology,49(4),385-392.
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Efficientproductionofrecombinantbarleyα-amylasehasbeenachievedin
Aspergillusniger.The
CDNAencodingα-amylaseisozyme1(AMY1)anditssignalpeptidewasplacedunderthecontrolofthe
Aspergillusnidulansglyceraldehyde-3-phosphatedehydrogenase(
gpd)promoterandthe
A.nidulanstrpCgeneterminator.Secretionyieldsupto60 mg/lwereobtainedinmediaoptimisedforα-amylaseactivityandlowproteaseactivity.TherecombinantAMY1(reAMY1)waspurifiedtohomogeneityandfoundtobeidenticaltonativebarleyAMY1withrespecttosize,p
I,andimmunoreactivity.N-terminalsequenceanalysisoftherecombinantproteinindicatedthattheendogenousplantsignalpeptideiscorrectlyprocessedin
A.niger.Electrosprayionisation/massspectrometrygaveamolecularmassforthedominantformof44 960 Da,inaccordancewiththelossoftheLQRSC-terminalresidues;glycosylationapparentlydidnotoccur.Theactivitiesofrecombinantandnativebarleyα-amylasesareverysimilartowardsinsolubleandsolublestarchaswellas2-chloro-4-nitrophenolβ-D-maltoheptaosideandamylose(degreeofpolymerisation=17).Barleyα-amylaseisthefirstplantproteinefficientlysecretedandcorrectlyprocessedby
A.nigerusingitsownsignalsequence.
TargetingoftheplantvacuolarsortingreceptorBP80isdependentonmultiplesortingsignalsinthecytosolictail.
daSilva,L.L.P.,Foresti,O.&Denecke,J.(2006).ThePlantCell,18(6),1477-1497.
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Althoughsignalsforvacuolarsortingofsolubleproteinsarewelldescribed,wehaveyettolearnhowtheplantvacuolarsortingreceptorBP80reachesitscorrectdestinationandrecycles.Toshedlightonreceptortargeting,weusedaninvivocompetitionassayinwhichatruncatedreceptor(greenfluorescentprotein-BP80)specificallycompeteswithsortingmachineryandcauseshypersecretionofBP80-ligandsfromtobacco(Nicotianatabacum)leafprotoplasts.WeshowthatboththetransmembranedomainandthecytosolictailofBP80containinformationnecessaryforefficientprogresstotheprevacuolarcompartment(PVC).Furthermore,thetailmustbeexposedonthecorrectmembranesurfacetocompetewithsortingmachinery.Mutationalanalysisofconservedresiduesrevealedthatmultiplesequencemotifsarenecessaryforcompetition,oneofwhichisatypicalTyr-basedmotif(YXXΦ).SubstitutionofTyr-612forAlacausespartialretentionintheGolgiapparatus,mistargetingtotheplasmamembrane(PM),andslowerprogresstothePVC.AroleinGolgi-to-PVCtransportwasconfirmedbygeneratingthecorrespondingmutationonfull-lengthBP80.ThemutantreceptorwaspartiallymistargetedtothePMandinducedthesecretionofacoexpressedBP80-ligand.FurthermutantsindicatethatthecytosolictailislikelytocontainotherinformationbesidestheYXXΦmotif,possiblyforendoplasmicreticulumexport,endocytosisfromthePM,andPVC-to-Golgirecycling.
Isolation,characterizationandinhibitionbyacarboseoftheα-amylasefromLactobacillusfermentum:comparisonwithLb.manihotivoransandLb.plantarumamylases.
Talamond,P.,Desseaux,V.,Moreau,Y.,Santimone,M.&Marchis-Mouren,G.(2002).ComparativeBiochemistryandPhysiologyPartB:BiochemistryandMolecularBiology,133(3),351-360.
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Extracellularα-amylasefromLactobacillusfermentum(FERMENTA)waspurifiedbyglycogenprecipitationandionexchangechromatography.Thepurificationwasapproximately28-foldwitha27%yield.TheFERMENTAmolecularmass(106000Da)isinthesamerangeastheonesdeterminedforL.amylovorus(AMYLOA),L.plantarum(PLANTAA)andL.manihotivorans(MANIHOA)α-amylases.TheaminoacidcompositionofFERMENTAdiffersfromtheotherlactobacilliconsideredhere,buthowever,indicatesthatthepeptidicsequencecontainstwoequalparts:theN-terminalcatalyticpart;andtheC-terminalrepeats.TheisoelectricpointofFERMENTA,PLANTAA,MANIHOAareapproximatelythesame(3.6).TheFERMENTAoptimumpH(5.0)isslightlymoreacidicandtheoptimumtemperatureislower(40°C).Rawstarchhydrolysiscatalyzedbyallthreeamylasesliberatesmaltotrioseandmaltotretaose.MaltoseisalsoproducedbyFERMENTAandMANIHOA.MaltohexaoseFERMENTAcatalyzedhydrolysisproducesmaltoseandmaltotriose.Finally,kineticsofFERMENTA,PLANTAAandMANIHOAusingamyloseasasubstrateandacarboseasaninhibitor,werecarriedout.Statisticalanalysisofkineticdata,expressedusingageneralvelocityequationandassumingrapidequilibrium,showedthat:(1)intheabsenceofinhibitorkcat/Kmare,respectively,1×109,12.6×109and3.2×109s-1M-1;and(2)theinhibitionofFERMENTAisofthemixednon-competitivetype(K1i=5.27µM;L1i=1.73µM)whiletheinhibitionofPLANTAAandMANIHOAisoftheuncompetitivetype(L1i=1.93µMand1.52µM,respectively).Whatevertheinhibitiontype,acarboseisastronginhibitoroftheseLactobacillusamylases.Theseresultsindicatethat,asfoundinporcineandbarleyamylases,Lactobacillusamylasescontaininadditiontotheactivesite,asolublecarbohydrate(substrateorproduct)bindingsite.
Theactivityofbarleyα-amylaseonstarchgranulesisenhancedbyfusionofastarchbindingdomainfromAspergillusnigerglucoamylase.
Juge,N.,Nøhr,J.,LeGal-Coëffet,M.F.,Kramhøft,B.,Furniss,C.S.,Planchot,V.,Archer,D.B.,Willianson,G.&Svensson,B.(2006).BiochimicaetBiophysicaActa(BBA)-ProteinsandProteomics,1764(2),275-284.
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Highaffinityforstarchgranulesofcertainamylolyticenzymesismediatedbyaseparatestarchbindingdomain(S
BD).In
Aspergillusnigerglucoamylase(GA-I),a70aminoacid
O-glycosylatedpeptidelinkerconnectsSBDwiththecatalyticdomain.Agenewasconstructedtoencodebarleyα-amylase1(AMY1)fusedC-terminallytothisSBDviaa37residueGA-Ilinkersegment.AMY1-SBDwasexpressedin
A.niger,secretedusingtheAMY1signalsequenceat25mg×L
-1andpurifiedin50%yield.AMY1-SBDcontained23%carbohydrateandconsistedofcorrectlyN-terminallyprocessedmultipleformsofisoelectricpointsintherange4.1–5.2.ActivityandapparentaffinityofAMY1-SBD(50nM)forbarleystarchgranulesof0.034U×nmol
-1and
Kd=0.13mg×mL
-1,respectively,werebothimprovedwithrespecttothevalues0.015U×nmol
-1and0.67mg×mL
-1forrAMY1(recombinantAMY1producedin
A.niger).AMY1-SBDshoweda2-foldincreasedactivityforsolublestarchatlow(0.5%)butnotathigh(1%)concentration.AMY1-SBDhydrolysedamyloseDP440withanincreaseddegreeofmultipleattackof3comparedto1.9forrAMY1.Remarkably,atlowconcentration(2nM),AMY1-SBDhydrolysedbarleystarchgranules15-foldfasterthanrAMY1,whilehigheramountsofAMY-SBDcausedmolecularovercrowdingofthestarchgranulesurface.
Impactofformulationandtechnologicalfactorsontheacrylamidecontentofwheatbreadandbreadrolls.
Claus,A.,Mongili,M.,Weisz,G.,Schieber,A.&Carle,R.(2008).JournalofCerealScience,47(3),546-554.
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Thisstudyclearlydemonstratesthatformulationandbakingtechnologyhavestronginfluenceontheacrylamidecontentinthebakedproducts.NaClplaysanambiguousrole:Whereaslowdosesupto2%loweredacrylamidebyinhibitionoftheenzymeactivities,higheradditionremarkablyincreasedthecontentsduetogrowthinhibitionoftheyeast.Theresultsofpreviousmodelstudiesconcerningtheinfluenceofcysteinecouldbeconfirmedinpilotplantexperiments.Itsadditiontothedoughresultedinsignificantlyloweracrylamidecontentwhereasitsapplicationtothecrustprovedtobeineffective.Furthermore,itwasdemonstratedthatenzyme-bearingbakeryimprovershadnoinfluenceonacrylamideformation.Inpilotplantexperimentsacrylamidewasreducedwithincreasingfermentationtime,andminimumacrylamidelevelswerealreadyreachedafter60minthusavoidingflattenedbreadsduetoprolongedamylaseactivity.Besidesformulationandfermentationalsoprocesstechnologyiscrucial.Asshownbyourdata,reducedbakingtemperatureandprolongedheattreatmentisfavorable.Furthermore,convectionovensseemtoenhanceacrylamideformationcomparedtodeckoven.
Heterologousexpressionofanα-amylaseinhibitorfromcommonbean(Phaseolusvulgaris)inKluyveromyceslactisandSaccharomycescerevisiae.
Brain-Isasi,S.,Álvarez-Lueje,A.&Higgins,T.J.V.(2017).MicrobialCellFactories,16(1),110.
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Background:Phaseolaminorα-amylaseinhibitor1(αAI)isaglycoproteinfromcommonbeans(
PhaseolusvulgarisL.)thatinhibitssomeinsectandmammalianα-amylases.SeveralclinicalstudiessupportthebeneficialuseofbeanαAIforcontrolofdiabetesandobesity.Commercialextractsof
P.vulgarisareavailablebuttheirefficacyisstillunderquestion,mainlybecausesomeoftheseextractscontainantinutritionalimpuritiesnaturallypresentinbeanseedsandalsoexhibitalowerspecificactivityαAI.TheproductionofrecombinantαAIallowstoovercomethesedisadvantagesandprovidesaplatformforthelarge-scaleproductionofpureandfunctionalαAIproteinforbiotechnologicalandpharmaceuticalapplications.
Results:AsyntheticgeneencodingαAIfromthecommonbean(
Phaseolusvulgariscv.Pinto)wascodon-optimisedforexpressioninyeasts(
αAI-OPT)andclonedintotheproteinexpressionvectorspKLAC2andpYES2.Theyeasts
KluyveromyceslactisGG799(andproteasedeficientderivativessuchasYCT390)and
SaccharomycescerevisiaeYPH499weretransformedwiththeoptimisedgenesandtransformantswerescreenedforexpressionbyantibodydotblot.Recombinantcoloniesof
K.lactisYCT390thatexpressedandsecretedfunctionalαAIintotheculturesupernatantswereselectedforfurtheranalyses.RecombinantαAIfrom
K.lactisYCT390waspurifiedusinganion-exchangeandaffinityresinsle
ADIngtotherecoveryofafunctionalinhibitor.TheidentityofthepurifiedαAIwasconfirmedbymassspectrometry.RecombinantclonesofS.cerevisiaeYPH499expressedfunctionalαAIintracellularly,butdidnotsecretetheprotein.
Conclusions:Thisisthefirstreportdescribingtheheterologousexpressionoftheα-amylaseinhibitor1(αAI)from
P.vulgarisinyeasts.Wedemonstratedthatrecombinantstrainsof
K.lactisand
S.cerevisiaeexpressedandprocessedtheαAIprecursorintomatureandactiveproteinandalsoshowedthat
K.lactissecretesfunctionalαAI.
AnalysisofNanobody–EpitopeInteractionsinLivingCellsviaQuantitativeProteinTransportAssays.
Früholz,S.&Pimpl,P.(2017).PlantProteinSecretion,MethodsinMolecularBiology,1662,pp.171-182,HumanaPress,NewYork,NY.
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Overthepastfewdecades,quantitativeproteintransportanalyseshavebeenusedtoelucidatethesortingandtransportofproteinsintheendomembranesystemofplants.Here,wehaveappliedourknowledgeabouttransportroutesandthecorrespondingsortingsignalstoestablishaninvivosystemfortestingspecificinteractionsbetweensolubleproteins.Here,wedescribetheuseofquantitativeproteintransportassaysintobaccomesophyllprotoplaststotestforinteractionsoccurringbetweenaGFP-bindingnanobodyanditsGFPepitope.Forthis,weuseasecretedGFP-taggedα-amylaseasareportertogetherwithavacuolar-targetedRFP-taggednanobody.Theinteractionbetweentheseproteinsisthenrevealedbyatransportalterationofthesecretoryreporterduetotheinteraction-triggeredattachmentofthevacuolarsortingsignal.