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1、CriticalReviewPharmacologieRoleofCysteineinAmelioratingorExacerbatingMineralToxicities1DAVIDH.BAKERANDGAILLCZARNECKI-MAÃœLDENDepartmentofAnimalSciencesandDivisionofNutritionalSciences,UniversityofIllinois,Urbana,IL61801DownloadedfromABSTRACTCysteine,viachelationreactions,am
2、elioratesbiochemicallesionscausedbyexcessiveingestionofseveraltraceelements.Becauseoralcysteineperseisconsiderablymoreprotectivethantheinvivometaboliccysteineprecursors,methionineorcystine,chelationofcysteinewithtraceelementslikelyoccursprimarilyinthegut,therebydecreasingab
3、sorptionofbothcysteineandthetraceelementinquestion.Hence,usingcopperasanexample,orallyadministeredcysteinemarkedlyimprovesgrowthandreduceslivercopperdepositioninchicksorratsfedahighlevelofinorganiccopper.Likewise,excessivecopperingestionimpairssulfuraminoacid(SAA)utilizatio
4、nandincreasesthedietaryrequirementforSAA.Cobaltandseleniumtoxicitiesjn.nutrition.orgarealsoamelioratedbyoralcysteineingestion,withtheresponsesbeingevenmorestrikingthanthoseoccurringwithcoppertoxicity.Whileinorganicarsenicpoisoningsaregenerallyamelioratedbyadministeringcyste
5、ineoracysteinederivative(e.g.,dimercaptopropanol),organicpentavalentarsenictoxicityisexacerbatedbycysteineadministration.Cysteineinthisinstanceactsasareducingagent,facilitatingconversionoforganicpentavalentarsenicalssuchasroxarsoneandarsanilicacidtothemoretoxicbivalentstate
6、.J.Nutr.117:1003-1010,1987.atSouthwestJiaotongUniversityonFebruary18,2017INDEXINGKEYWORDS:•cysteine•methionine•metal•chelation•copper•cobalt•selenium•arsenic•roxarsone•chick•ratBecausemethionineisthesulfuraminoacid(SAA)permittingsulfationofthesedrugsto
7、facilitateurinarythatisadietaryessential,andbecausecystineandmeexcretion(11).thioninearetheSAAfoundingreatestabundanceinSinceintracellularcysteineconcentrationisgenerfoodandtissueproteins,littleattentionisgiventotheallyratelimitinginthecontrolofGSHbiosynthesisnutritionaland
8、metabolicroleofcysteine.Yetcysteine(12),Meisterandcolleagueshavebeenactivelyinisth
