HighpurityAmylaseHRReagent–4vialsforthemeasurementofα-amylaseforresearch,biochemicalenzymeassaysandinvitrodiagnosticanalysis.
Analysisoffeedenzymes.
McCleary,B.V.(2001).“EnzymesinFarmAnimalNutrition”,(M.BedfordandG.Partridge,Eds.),CABInternational,pp.85-107.
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Enzymesareaddedtoanimalfeedtoincreaseitsdigestibility,toremoveanti-nutritionalfactors,toimprovetheavail
ABIlityofcomponents,andforenvironmentreasons(CampbellandBedford,1992;Walsh
etal.,1993).Awide-varietyofcarbohydrase,protease,phytaseandlipaseenzymesfinduseinanimalfeeds.Inmonogastricdiets,enzymeactivitymustbesufficientlyhightoallowfortherelativelyshorttransittime.Also,theenzymeemployedmustbeabletoresistunfavourableconditionsthatmaybeexperiencedinfeedpreparation(e.g.extrusionandpelleting)andthatexistinthegastrointestinaltract.Measurementoftracelevelsofenzymesinanimalfeedmixturesisdifficult.Independentoftheenzymestudied,manyoftheproblemsexperiencedaresimilar;namely,lowlevelsofactivity,extractionproblemsinactivationduringfeedpreparation,non-specificbindingtootherfeedcomponentsandinhibitionbyspecificfeed-derivedinhibitors,e.g.specificxylanaseinhibitorsinwheatflour(Debyser
etal.,1999).
Measurementofcerealα-Amylase:Anewassayprocedure.
McCleary,B.V.&Sheehan,H.(1987).JournalofCerealScience,6(3),237-251.
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Anewprocedurefortheassayofcerealα-amylasehasbeendeveloped.Thesubstrateisadefinedmaltosaccharidewithanα-linkednitrophenylgroupatthereducingendofthechain,andachemicalblockinggroupatthenon-reducingend.Thesubstrateiscompletelyresistanttoattackbyβ-amylase,glucoamylaseandα-glucosidaseandthusformsthebasisofahighlyspecificassayforα-amylase.Thereactionmixtureiscomposedofthesubstrateplusexcessquantitiesofα-glucosidaseandglucoamylase.Nitrophenyl-maltosaccharidesreleasedonactionofα-amylaseareinstantaneouslycleavedtoglucoseplusfreep-nitrophenolbytheglucoamylaseandα-glucosidase,suchthattherateofreleaseofp-nitrophenoldirectlycorrelateswithα-amylaseactivity.TheassayprocedureshowsanexcellentcorrelationwiththeFarrand,theFallingNumberandthePhadebasα-amylaseassayprocedures.
Anewprocedureforthemeasurementoffungalandbacterialα-amylase.
Sheehan,H.&McCleary,B.V.(1988).BiotechnologyTechnniques,2,289-292.
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Aprocedureforthemeasurementoffungalandbacterialα-amylaseincrudeculturefiltratesandcommercialenzymepreparationsisdescribed.Theprocedureemploysend-blocked(non-reducingend)p-nitrophenylmaltoheptaosideinthepresenceofamyloglucosidaseandα-glucosidase,andisabsolutelyspecificforα-amylase.Theassayprocedureissimple,reliableandaccurate.
Measurementofα-AmylaseinCereal,FoodandFermentationProducts.
McCleary,B.V.&Sturgeon,R.(2002).CerealFoodsWorld,47,299-310.
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InGeneral,thedevelopmentofmethodsformeasuringα-amylaseispioneeredintheclinicalchemistryfieldandthentranslatedtootherindustries,suchasthecerealsandfermentationindustries.Inmanyinstances,thistransferoftechnologyhasbeendifficultorimposs
IBLetoachieveduetothepresenceofinterferingenzymesorsugarsandtodifferencesinthepropertiesoftheenzymesbeinganalysed.Thisarticledescribesmanyofthecommonlyusedmethodsformeasuringα-amylaseinthecereals,food,andfermentationindustriesanddiscussessomeoftheadvantagesandlimitationsofeach.
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-blockedp-nitrophenylmaltoheptaoside(BPNPG7)inthepresenceofexcessquantitiesofthermostableα-glucosidase.TheblockinggroupinBPNPG7preventshydrolysisofthissubstratebyexo-actingenzymessuchasamyloglucosidase,α-glucosidase,andβ-amylase.Whenthesubstrateiscleavedbyendo-actingα-amylase,thenitrophenyloligosaccharideisimmediatelyandcompletelyhydrolyzedtop-nitrophenolandfreeglucosebytheexcessquantitiesofα-glucosidasepresentinthesubstratemixture.Thereactionisterminated,andthephenolatecolordevelopedbytheadditionofanalkalinesolutionismeasuredat400nm.AmylaseactivityisexpressedintermsofCeralphaunits;1unitisdefinedastheamountofenzymerequiredtorelease1µmolp-nitrophenyl(inthepresenceofexcessquantitiesofα-glucosidase)in1minat40°C.Inthepresentstudy,15laboratoriesanalyzed16samplesasblindduplicates.Theanalyzedsampleswerewhitewheatflour,whitewheatflourtowhichfungalα-amylasehadbeenadded,milledmalt,andfungalandbacterialenzymepreparations.Repeatabilityrelativestandarddeviationsrangedfrom1.4to14.4%,andreproducibilityrelativestandarddeviationsrangedfrom5.0to16.7%.
Thickenersfordysphagicpatients:comparisonofanewamylaseresistantproductwithfourstandardstarch-basedproducts-invitrostudy.
Oudhuis,A.A.C.M.,Helmens,H.J.&Bos,M.A.ESPEN2:e83.2007.
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Patientswithdysphagiaarecommonlyprescribedthickeneddrinkstopromotesafeswallowing.Standardstarch-basedthickenersaresensitivetoα-amylase,andmaythinduringconsumptionresultinginpatientsnotreceivingtheirprescribedconsistency.Thisstudycomparestheeffectofhumansalivaontheconsistencyofdrinks(water,fullfatmilkandblackcoffee)thickenedwithanewlydevelopedthickenerwithα-amylaseresistantfeaturesandfourstandardstarch-basedthickeners.
Pharmacometricsof3-Methoxypterostilbene:AComponentofTrADItionalChineseMedicinalPlants.
Martinez,S.E.,Sayre,C.L.&Davies,N.M.(2013).Evidence-BasedComplementaryandAlternativeMedicine,ArticleID261468.
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3-Methoxypterostilbeneisanaturallyoccurringstilbenewithpotentialinthetreatmentofdiabetes.Thepreclinicalpharmacokineticsandpharmacodynamicsof3-methoxypterostilbenewereevaluatedinthepresentstudy.TherightjugularveinsofmaleSprague-Dawleyratswerecannulated.Theratsweredosed10 mg/kgor100 mg/kgof3-methoxypterostilbeneintravenously(IV)ororally(PO),respectively.Serumandurinesampleswereanalyzedusingapreviouslyvalidatedreversed-phaseHPLCmethod.SerumAUC,serumt1/2,urinet1/2,Cltotal,andVdforIVdosingwere48.1±23.8 µg/h/mL, 18.1±10.9h,9.54±1.51 h,47.8±23.7 L/h/kg,and5.11±0.38 L/kg,respectively(mean±SEM,n=4).SerumAUC,serumt1/2,urinet1/2,Cltotal,andVdforPOdosingwere229.8±44.6 µg/h/mL,73.3±8.91 h,20.6±3.01 h,0.48±0.008 L/h/kg,and52.0±10.5 L/kg,respectively(mean±SEM,n=4).Bioavailabilityofthestilbenewasdeterminedtobe50.6% ±10.0%.A3-methoxypterostilbeneglucuronidatedmetabolitewasdetectedinbothserumandurine.3-Methoxypterostilbeneexhibitedantidiabeticactivityincludingα-glucosidaseandα-amylaseinhibitionaswellasconcentration-dependentantioxidantcapacitysimilartoresveratrol.3-Methoxypterostilbenealsoexhibitedanti-inflammatoryactivity.3-Methoxypterostilbeneappearstobeabioactivecompoundandmaybeusefulinreducingpostprandialhyperglycemia.
Dose-andtissue-specificinteractionofmonoterpeneswiththegibberellin-mediatedreleaseofpotatotuberbuddormancy,sproutgrowthandinductionofα-amylasesandβ-amylases.
Rentzsch,S.,Podzimska,D.,Voegele,A.,Imbeck,M.,Müller,K.,Linkies,A.&Leubner-Metzger,G.(2012).Planta,235(1),137-151.
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Gibberellins(GA)areinvolvedinbuddormancyreleaseinseveralspecies.WeshowherethatGA-treatmentreleasedbuddormancy,initiatedbudsproutingandpromotedsproutgrowthofexcisedpotatotuberbuddiscs(‘eyes’).Monoterpenesfrompeppermintoil(PMO)andS-(+)-carvone(CAR)interactwiththeGA-mediatedbuddormancyreleaseinahormesis-typeresponse:lowmonoterpeneconcentrationsenhancedormancyreleaseandtheinitiationofbudsprouting,whereashighconcentrationsinhibitit.PMOandCARdid,however,notaffectsproutgrowthrateafteritsonset.WefurthershowthatGA-induceddormancyreleaseisassociatedwithtissue-specificregulationofα-andβ-amylases.Molecularphylogeneticanalysisshowsthatpotatoα-amylasesclusterintotwodistinctgroups:α-AMY1andα-AMY2.GA-treatmentinducedtranscriptaccumulationofmembersofbothα-amylasegroups,aswellasα-andβ-amylaseenzymeactivityinsproutand‘sub-eye’tissues.Insprouts,CARinteractswiththeGA-mediatedaccumulationofα-amylasetranscriptsinanα-AMY2-specificanddose-dependentmanner.LowCARconcentrationsenhancetheaccumulationofα-AMY2-typeα-amylasetranscripts,butdonotaffecttheα-AMY1-typetranscripts.LowCARconcentrationsalsoenhancetheaccumulationofα-andβ-amylaseenzymeactivityinsprouts,butnotin‘sub-eye’tissues.Incontrast,highCARconcentrationshavenoappreciableeffectinsproutsontheenzymeactivitiesandtheα-amylasetranscriptabundancesofeithergroup.Thedose-dependenteffectsontheenzymeactivitiesandtheα-AMY2-typeα-amylasetranscriptsinsproutsarespecificforCARbutnotforPMO.Differentmonoterpenesthereforemayhavespecifictargetsfortheirinteractionwithhormonesignallingpathways.
Akineticmodeltoexplainthemaximuminα-amylaseactivitymeasurementsinthepresenceofsmallcarbohydrates.
Baks,T.,Janssen,A.E.&Boom,R.M.(2006).BiotechnologyandBioengineering,94(3),431-440.
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Theeffectofthepresenceofseveralsmallcarbohydratesonthemeasurementoftheα-amylaseactivitywasdeterminedoverabroadconcentrationrange.Atlowcarbohydrateconcentrations,adistinctmaximumintheα-amylaseactivityversusconcentrationcurveswasobservedinseveralcases.Athigherconcentrations,allcarbohydratesshowadecreasingα-amylaseactivityatincreasingcarbohydrateconcentrations.Ageneralkineticmodelhasbeendevelopedthatcanbeusedtodescribeandexplainthesephenomena.Thismodelisbasedontheformationofacarbohydrate–enzymecomplexthatremainsactive.Itisassumedthatthiscomplexisformedwhenacarbohydratebindstoα-amylasewithoutblockingthecatalyticsiteanditssurroundingsubsites.Furthermore,thekineticmodelincorporatessubstrateinhibitionandsubstratecompetition.Dependingonthecarbohydratetypeandconcentration,themeasuredα-amylaseactivitycanbe75%lowerthantheactualα-amylaseactivity.Themodelthathasbeendevelopedcanbeusedtocorrectfortheseeffectsinordertoobtaintheactualamountofactiveenzyme.
TowardaMicrofluidic‐BasedRapidAmylaseAssaySystem.
Holmes,R.J.,Summersgil,P.,Ryan,T.,Brown,B.J.T.,Mockbil,A.,Grieve,B.D.&Fielden,P.R.(2009).JournalofFoodScience,74(6),N37-N43.
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Thisarticledescribesworkintoaprototypesystemfortheassayofamylase,usingmicrofludictechnologies.Thenewsystemhasasignificantlyshortercycletimethanthecurrentlaboratorymethods,whichgenerallyusemicrotitreplates,yetiscapableofgeneratingsignificantlysuperiorresults.Assuch,wehaveshownthatsensitivityisenhancedbyafactorof10inthestandardassaytrials,andbyafactorof2inthereal-samplelabtrials.Inbothassays,theuseofamicroreactorsystemreducedthereactiontimebyafactorof6.2,from20minincubationto3.2min.Basingtheconclusiononthe
MegazymeCerealphaStandardMethod,andusingtheCerealphaunitsasameasureofassayefficiency,thetypicalresponseforthemicrofluidicassaywasshowntobe1.0×10
-3CU/mL(standarddeviation[SD]2.5×10
-4CU/mL),comparedto2.56×10
-4CU/mL(SD5.94×10
-5CU/mL)forthestandardmacroassay.Itisbelievedthatthisimprovementinthereactionschematicsisduetotheinherentadvantagesofmicrofluidicdevicessuchassuperiormixing,higherthermalefficiency,andenhancedreactionkinetics.
EffectofGelatinizationandHydrolysisConditionsontheSelectivityofStarchHydrolysiswithα-AmylasefromBacilluslicheniformis.
Baks,T.,Bruins,M.E.,Matser,A.M.,Janssen,A.E.M.&Boom,R.M.(2008).JournalofAgriculturalandFoodChemistry,56(2),488-495.
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Enzymatichydrolysisofstarchcanbeusedtoobtainvariousvaluablehydrolyzateswithdifferentcompositions.Theeffectsofstarchpretreatment,enzymeadditionpoint,andhydrolysisconditionsonthehydrolyzatecompositionandreactionrateduringwheatstarchhydrolysiswithα-amylasefrom
Bacilluslicheniformiswerecompared.S
USPensionsofnativestarchorstarchgelatinizedatdifferentconditionseitherwithorwithoutenzymewerehydrolyzed.Duringhydrolysis,theoligosaccharideconcentration,thedextroseequivalent,andtheenzymeactivityweredetermined.Wefoundthatthehydrolyzatecompositionwasaffectedbythetypeofstarchpretreatmentandtheenzymeadditionpointbutthatitwasjustminimallyaffectedbythepressureappliedduringhydrolysis,aslongasgelatinizationwascomplete.Thedifferencesbetweenhydrolysisofthermallygelatinized,high-pressuregelatinized,andnativestarchwereexplainedbyconsideringthegranulestructureandthespecificsurfaceareaofthegranules.Theseresultsshowthatthehydrolyzatecompositioncanbeinfluencedbychoosingdifferentprocesssequencesandconditions.