Megazyme/Mannazyme Tablets/TMNZ1000T/1,000 Tablets

Asimpleassayprocedureforβ-D-mannanaseenzymehasbeendevelopedwhichemployscarobD-galacto-D-mannandyedwithRemazolbrilliantBlue.Additionally,theprocedureisquantitative,relativelysensitive,andhighlyspecificforβ-D-mannanaseenzyme.Itcanbereadilyusedforthedeterminationofβ-D-mannanaseactivityincrudeenzymepreparationsandcolumn-chromatographyeluates.

Chemicallymodifiedpolysaccharidesarewidelyusedasrheologymodifiersinseveralapplications,suchasfoodandfeed,personalcare,detergents,textileprinting,buildingmaterials,paintsandcoating,papermanufacturing,andoiloperations.Hydroxyalkylation,performedwithethyleneorpropyleneoxide,isoneofthemostcommonchemicalreactionsappliedtomodulatetherheologicalprofileandotherpropertiesofpolysaccharides.Hydroxyethylcellulose(HEC)andhydroxypropylguar(HPG)arewidelyusedasthickeningandstabilityagentsinwaterbornepaints.Hydroxyalkylationalsoincreasestheresistanceofpolysaccharidestoenzymedegradationduetosterichindrancebythesubstituentsonthesusceptiblebondsalongthepolysaccharidebackbone.Thisfeatureof“enzymeresistance”isoftenreferredtoas“biostability,”yetitdoesnotmimicareal-lifesituationofmicrobialcontaminationthatcanoccurinaproductionplantorstorehouse.WehavecomparedviscositydecreasesofHECsandHPGsinthepresenceoftheirspecifichydrolyzingenzyme(cellulaseandmannanase,respectively)toactualmicrobialcontaminationbyconsortiaoffungiorbacteria.WefoundthatthebehaviourofHECandHPGsolutionsinoculatedwithmicroorganismsdiffersandcannotbepredictedfromenzymechallengedataalone.Thus,“enzymeresistance”and“biostability”arenotequivalentproperties.Forpracticalpurposes,itisimportanttobearthisinmindwhenselectingthemostappropriatepolysaccharidethickener,themanufacturingconditionsofwaterbornepaintsandtheoptimalstageofbiocideaddition.

Chemicalmodificationsofgalactomannansareappliedtoimproveand/ormodifytheirsolubility,rheologicalandfunctionalproperties,buthavelimitedspecificityandareoftendifficulttocontrol.Enzymaticreactions,catalyzedundermildprocessconditions,suchasdepolymerization,debranchingandoxidation,representaviableandeco-friendlyalternative.Inthisstudy,wedescribeoxidationofguargalactomannanprimaryhydroxylgroupsbyafungallaccaseusingthestableradicalTEMPOasmediator.Fourfungallaccaseswereinvestigatedfrom:Trametesversicolor,Myceliophthorathermophila,Thielaviaarenaria,Cerrenaunicolor.ThelaccasefromT.versicolorwasfoundtoefficientlyoxidizeTEMPOandtobefreeofmannanasesideactivity.OxidationofgalactomannanwiththisenzymeplusTEMPObroughtaboutaten-foldincreaseinviscosityofaguargalactomannansolutionandaltereditsrheologicalprofile,byconvertingaviscouspolysaccharidesolutionintoanelasticgel.Thisstructuralmodificationispresumablyduetoformationofinter-chainhemiacetalicbondsbetweennewlygeneratedcarbonylgroupsandfreeOHgroups,yieldingacross-linkedgel.Thesefindingscouldbeofpracticalimportance,consideringthatpolysaccharideswithhighviscosity,gellingandelasticpropertiescanfindinterestingandnovelapplicationsasthickeners,viscosifiersandemulsionstabilizersinseveralindustrialapplicationssuchas:personalcare,oiloperations,papercoating,paints,constructionandmining.

Guargalactomannan(referredtoasguargum)isaversatilepolysaccharide,obtainedfromtheseedsoftheshrubCyamopsistetragonolobus,whichfindsseveralapplicationsineitheritsnativeorchemicallymodifiedform.Fortextileprinting,guargumcanalsobepartiallydepolymerisedinordertopromotedyepenetration,improveswellinginwaterandachievethedesiredrheologicalproperties.Guargumisobtainedfromguarseedsbyathermo-mechanicalprocessthatleavesca.3%oflargelyinsolubleproteinsinthegum,originatingfromtheendospermsaleuronelayer.Whenprintingsilkfabricswithacidorpremetalliseddyes,guarendogenousinsolubleproteinsbindtightlytoanionicdyes,causingdepositionofcolouredaggregatesonthefabric.Thiscausesimperfectionsontheprintedfabricintheformoftiny,butvisible,‘dots’,whichlowersthequalityofthefinalarticles.Inordertoeliminate‘dotting’,anovelprintingthickenercomposedofdepolymerisedguargummixedwithabioengineeredsubtilisinproteasehasbeendeveloped.Uponsolubilisationofthegum,andduringpreparationoftheprintingpastemixture,theproteasehydrolysesguarguminsolubleproteins,generatingsolublepeptidesthatarewashedoffbythepost-printingtreatmentsofthefabric.Thisenzymaticapplicationprevents‘dotting’andsignificantlyimprovesthequalityofthesilkprint,withoutanymeasurabletensilestrengthlossofthefabric.