生物化学词典.doc

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1、AacetylCoAcarboxylaseAnenzymethatcatalyzestheATP-dependentsynthesisofmalonylCoAfromacetylCoAandcarbondioxide,thecommittedstepinfattyacidsynthesis.acetylcholinereceptorAligand-gatedchannelthatpromotesalargeinwardcurrentofsodiumionsandtriggersanactionpotential;composedofapentameroffourkindsofpoly

2、peptidesubunits,thechannelopenstoallowpassageofsodiumandpotassiumionswhentwoacetylcholinemoleculespromotetransientopeningofthechannel.acetylcholinesteraseAnenzymeinthesynapticcleftthatconvertsacetylcholineintocholineandacetate;thisenzymepromotestheclosingoftheacetylcholine-receptormembranebyrap

3、idlyreducingtheconcentrationofacetylcholineintheregionbetweenthepresynapticandthepostsynapticmembranes.acetyllysine-bindingdomainAdomainconsistingofafour-helixbundlethatbindspeptidescontainingacetyllysine.Alsocalledabromodomain.actinAhighlyconservedproteinfoundinalleukaryotes;instriatedmuscle,i

4、tformsthethinfilamentsofthesarcomereandactivatestheATPaseofmyosin.actinomycinApolypeptideantibioticfromStreptomycesthatinhibitstheelongationphaseofRNAsynthesisbybindingtodouble-helicalDNAbyintercalatingwithit,therebypreventingtheDNAfromservingasatemplate.actionpotentialTheincreaseinmembranepote

5、ntialandthechangesinsodiumandpotassiumconductancesthatresultfromalterationsinthepermeabilityoftheaxonmembranetothoseions.Alsocallednerveimpulse.activatedcarriersSmallmoleculescarryingactivatedfunctionalgroupsthatcanbedonatedtoothermolecules;forinstance,ATPcarriesactivatedphosphategroupsandCoAca

6、rriesactivatedacylgroups.activatedmethylcycleAseriesofreactionsinwhichS-methylgroupsfrommethionineareconvertedintoabiochemicallyreactiveformthroughinsertionintoanadenosylgroup;anactiveS-methylgroupcanbetransferredfromS-adenosylmethioninetoacceptormoleculessuchasnorepinephrine.Theremainingpartof

7、thecycleincludestheregenerationofmethioninefromhomocysteineandN5-methyltetrahydrofolate.activationdomainThestructuralregionofatranscriptionfactorthatfacilitatestranscriptioninsomemanner.SeealsoDNA-bindingdomain.BacktoTopactivesite