生物化学词典

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aｃｅtｙlＣoAcarbｏｘyｌaseＡnenｚyｍethatcａtaｌyzｅｓtｈeＡTP—depｅnｄentsｙnthesｉsofmａloｎylCoAｆromaｃｅtylＣｏAandcaｒbondioxide，theｃommｉttｅdstｅｐinfaｔtyaｃiｄsｙnｔhesis.

ａcｅtylcholinereｃeptoｒAliｇaｎd-gａtedｃhannelthatｐroｍoteｓaｌａｒgｅinwaｒdcurrentoｆsodiumionsaｎdtrｉggerｓanacｔiｏnpotentｉal；ｃomｐosｅｄｏfaｐentａmｅｒｏｆfｏurkindsofｐoｌypｅｐtidesubuｎits,thecｈaｎnelopeｎstoalｌowｐａssageｏｆsodiｕmandpotaｓsiuｍionｓwｈｅntｗoacetｙlcholineｍｏlｅculｅspromotetransientopeningｏｆｔhｅchannel．

acｅtｙｌcholｉnestｅraseAnｅnzｙｍｅiｎthesyｎaｐtiｃcleｆｔthatconverｔsacetylchoｌineinｔocholｉneandａcetate；thisenzｙmeｐromotesｔhecｌosｉngoｆtｈeacetyｌchoｌｉnｅ—ｒeｃeｐtorｍembrａnebyｒapiｄlyｒedｕｃｉnｇｔｈeconcｅnｔrationoｆａceｔylcholineinｔheｒegionbetwｅｅnｔｈepreｓynａpticandｔhepostsｙｎaｐticmembranes。

acetyｌlysine-bindingｄｏmainＡdomaiｎｃoｎsiｓtingｏｆafｏｕｒ—ｈelixbｕndｌethatｂｉnｄspeptiｄescontainｉｎｇacetylｌｙsinｅ。Alsoｃａlｌｅdabroｍodomａin.

ａcｔinＡhiｇhlyｃｏnservｅdpｒoteｉnfounｄinａlleukａｒyｏtes；inｓtriatedmusclｅ,itformｓｔhethinfｉlamenｔsoftｈesarcomereanｄaｃｔivaｔestheATPaｓｅｏfmｙosin。

actｉnｏmycinApoｌypeｐtｉdeaｎtibioticfroｍＳtreptomｙcesｔｈatｉnhｉbitstheelongａtioｎｐhａsｅofRＮＡsynthｅsisbｙｂindｉngｔodｏｕble-helicalDNAbyintercalａtiｎｇｗithiｔ，ｔherebｙpｒｅventｉnｇtｈeDNAfromserｖiｎgasatｅｍpｌａｔe．

actionpｏtenｔｉalTheｉncreaｓeinｍemｂrａnepotｅｎｔialanｄthecｈangesinsｏｄiｕmandｐotassiｕｍｃonduｃtancesthaｔreｓultfromaｌtｅratiｏｎsintheｐeｒmｅａｂilityoftheaxonｍembrａnetoｔhoｓｅions.Alsoｃａlledｎeｒveimｐｕlse．

actｉvatedcａｒrieｒsSmalｌmoｌeculｅｓcarryｉngactiｖaｔｅdfunctionalｇrｏupsthaｔｃanbeｄonａtedｔootｈeｒｍoleｃulｅs；forinstance，ATＰcarriesａcｔｉｖatｅdphoｓｐhategｒｏupｓandCｏAcarrｉesactｉｖａｔedａcylgroｕps。

activaｔedmethylcyclｅAseriesofｒｅａｃtｉoｎsinwhiｃhS—metｈylｇroupｓｆｒommetｈiｏnｉneａｒecｏｎvertｅdintoaｂｉochｅmicａllｙrｅactivｅformthrｏughinｓertｉonintoaｎadenｏsylgｒouｐ;aｎａcｔiveS－mｅｔhylgroupcaｎbetransfeｒredｆromＳ－adenosｙlmｅｔhｉoninetｏacｃeptorｍolecuｌessuchasnoreｐiｎephｒｉnｅ．TheremainingpartｏfｔhecyｃleiｎcludestheregｅneｒatｉoｎoｆmethionineｆromhｏmｏｃysｔeiｎeanｄN５－ｍethyltetraｈydｒofｏlaｔｅ。

acｔivaｔｉondoｍainＴhestructurａlreｇioｎｏfatranｓcrｉｐtionfactｏrtｈaｔfacilｉtatestrａｎsｃｒipｔioniｎsomeｍａnnｅｒ．ＳeealｓoＤNA－biｎdingdomain。

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aｃtivesiteAspｅｃifiｃｒegｉoｎoｆanｅnzymeｔhaｔbindstheｓｕbstrateanｄｃarriｅsoｕtｃaｔａｌysis。

aｃtivetｒａｎspｏrｔTheｔrａnsｐoｒｔofａnｉonoramｏlecuｌｅagaｉnｓtaｃonceｎｔrａtｉonｇradienｔ，whereDGfoｒthｅtranspｏｒｔedｓｐeｃiesisposiｔive;thepｒocessmustbｅcｏupledtoaｎinｐutoｆfreeeｎeｒgｙfroｍasｏurcesｕcｈasATP，anelｅｃtrocｈemicalgradiｅｎtoｆNａ+orK+,orｌｉgｈt.

ａctｏmyosinAcoｍplexｆorｍedｉnｖｉtrｏbetweenmｙosinａndactｉｎthａtdｉsplaysｃertaiｎproｐｅrtiｅsofｍusclｅs，sucｈaｓcontrａctingｉntｈｅprｅsenceofAＴP．

acylａｄenylateAmixedaｎhydrideｉnwhichtｈeｃａｒboxylgrｏupｏｆａmolｅcuｌeisｌinkedtoｔheｐhoｓphorylgroｕpoｆAMＰ；theｆormatｉoｎｏfacylａdenylaｔｅsisameaｎsｏfaｃｔivatingcarbｏxyｌgｒoupｓｉnｂioｃhemiｃalreactiｏns，suｃｈａsthｅforｍaｔｉｏnｏfｆaｔtｙacｙlCoAmｏlecｕlｅｓfroｍａfｒeｅｆaｔtｙaｃidａndcoenzymeA.

acyｌcarrierｐroteinAbａcterialｐolypeptiｄethａtisｌinkeｄtophoｓpｈopaｎtｅtｈeineaｎdaｃtｓaｓacarrierofthｅｇrowingfaｔtyaｃylchａｉnduｒingｆattyacidbｉosynｔｈｅsis.

adaptａtionThｅresetｔinｇoｆtheｓensｉtiｖｉtyｌevelofrｅｃeptorsduetoｔｈecontinuedｐrｅsenceｏfｌiｇaｎds.Alsoｃalleｄdeｓensiｔizaｔioｎ．

ａdditiontoｏrｆormatｉonofdｏｕblｅｂｏｎｄAreaｃtioｎinwｈichａfunctｉonalｇrｏｕpisaddｅｄtoａdoubｌｅbondorａgrｏupisｒeｍｏvedfromamoleｃulｅtoｆormａdoubｌｅboｎd.

aｄｅnｙlaｔecyｃlasｅAnenｚｙmethatgenｅｒatescAＭP,aseconｄmesseｎｇｅr,ｆｒomATP。

ａｄeｎylateｃyclａsｅcascadeＡsiｇｎal-traｎsductioｎpaｔhwaｙｔhateｍpｌoyscAＭＰanｄａｓｅriｅｓofenzymestｏｃoｎvertanextｒaｃellularｓｉgnaｌiｎtoａniｎtracelｌｕlarsｉｇnal．

adipocyｔｅsＭammａliaｎｃellsｔhataｒethemajorｓtｏｒagesitｅｆoｒｔriａcylｇlyｃｅrolｓ.

A-DNAheliｘAｒighｔ－handeddoubleｈeliｘmａdeupofaｎtiｐarａllｅlstrandｓｈeｌdｔogetheｒｂｙA-TandG—Cbａsepaiｒinｇ;itiｓwiderandshortertｈaｎＢ—DNAandiｓseｅｎｉndehｙdratedDNAaswellａｓindoublｅsｔraｎdｅdreｇionsofRNAandinRNA—ＤＮAhelices。

aｅroｂicInthｅprｅsencｅofoｘygｅn.

ａfｆｉｎitｙcｈromａtographyＡproｔein-purｉfiｃatioｎtechniｑuｅbasedoｎthｅｈｉghａffinityofmanyprｏtｅiｎsforspeｃｉｆiｃchemicａｌｇroups．Sucｈgroｕpsａrｅattachedｔoanｉｎertmatriｘ，andｔheｐｒｏtｅinｓampleisａｐplｉｅｄ;ｏｎlythosepｒoteinswithanaffｉｎｉｔyforthegroupswｉllbｉｎｄ.

affｉｎitylａbeｌiｎgAmｅanｓｏfｍappiｎｇtheactiｖesitｅofａnenzymebyｕsingaｓubｓtrateanalogthatbinｄstotheａctivesiｔeandｆorｍｓacovalentbｏnｄwithａnｅaｒbyaminｏacｉｄ.

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ａgoｎiｓtsＭoleculesthatｂinｄtorｅceptoｒprotｅｉnｓandtｒiggeｒsignaｌinｇpatｈwａys．

aｌｃapｔoｎｕriaＡｒelativeｌyhａrmleｓshｅｒediｔarydisorderｒeｓuｌｔiｎgfrｏmｔｈeaberrａnｔbreaｋdownofｔyｒosｉnｅａndｐhｅｎylａｌanｉne.

alcohｏlicfermｅnｔationThｅａnaerobｉcconversｉｏｎoｆglｕcoｓeintoeｔhanolwiｔhtheｃoｎｃoｍｉｔantproduｃtｉoｎｏfATP.

aldolcｏｎdｅｎｓatioｎＴhecombinatｉoｎoftwocarbonylcompouｎｄs（e。g．，analdｅhydeａndａketone）tｏfｏrmaβ－hyｄroｘyｃarbonyｌcｏｍｐｏund，orａｌｄoｌ．

aｌdｏseAmoｎoｓａcchａｒidewhoｓeC－1carｂonaｔｏmｃｏntaiｎsaｎaｌdehydｅｇｒoup.

aｌleleｓAltｅrnatｉvｅfｏｒmsｏfaｇeneataparticｕlarsiteonachroｍosome.

alloｓtericｉnterａcｔionAninteracｔiｏnbetweenasmaｌｌｍolｅcｕｌe（aｌiｇand）aｎdasｉteonaproteiｎtｈatｍaybesｏmedｉstaｎceawayfromｔhｅaｃｔivesiｔe；thｅｉｎｔeｒacｔiｏncaｕsｅsacｏnformationalchａngeandcｏnsequeｎtａｌｔerａｔiｏnintｈｅcatａlyticactivｉtyofthｅprotein。

αhｅlixAｃommoｎstｒuctuｒａｌｍotifinprｏteinｓ，iｎｗhichapolｙｐeptideｍaincｈａｉnｆｏrmstheiｎneｒpartｏfarighｔ－handeｄhelix,withthesidｅchａinsextendingoutwａrｄ；thehelixissｔabilizedｂｙintｒaｃｈainｈｙdｒogenbｏndsｂｅtｗeeｎNHａnｄCＯｇroupｓoｆthemａinchaiｎ．

α—ketｏglutaｒａｔｅdｅhyｄrｏgenａsｅＡｃiｔrｉcaｃiｄcｙcleｅnｚｙｍethatcａtａlｙzｅstheoxｉdativeｄｅcａrboxylationｏfα—ｋeｔoglutaratｅtｏyｉeｌdsｕcciｎyｌCｏＡ.Thisenzyｍe,whichhelｐstoｒegulatetheｒａteｏｆthecitricaciｄcycle,isstrucｔurａllｙaｎdmｅchaｎisticallysiｍiｌaｒtothepyruvateｄehyｄrogeｎａsecｏmplex.

aｌternatｉｖeｓpｌicinｇＴhegeｎｅrａtioｎｏｆunｉqｕebutrelａｔｅｄmＲNＡmoleculｅsbｙthｅdifｆｅrenｔialspliciｎgoｆtheｐｒｅ-ｍRＮAtranscｒiｐt。ByallowingｔhesyｎthｅsisofmorｅｔｈanonｅmＲNAmolｅｃuleｆｒoｍaｐrｅmRNAｔrａｎscript，alterｎativesｐｌｉcｉngincreaseｓｔheｅｎｃoｄｉnｇpotｅntiａｌofｔhｅgenｏme.

ＡmａnitiｎAcyclicｏcｔａpｅptidefromtｈemuｓｈroｏmAmanitaphaｌlｏｉdes(ｔｈedestｒｏｙinｇａnｇｅｌ）ｔhaｔiｓａpoｔentinhibitoroftheeｌongatioｎｐhaseofＲNAsｙｎｔhesiscａtａlyzｅdbｙRＮＡpolｙｍｅraseII．

AｍeｓｔestAｓiｍplｅ，ｒapiｄmeａnsｏfdetectiｎgcaｒcｉnoｇensbymｅaｓuringａcｈemｉcal’sabilｉtytoiｎducｅmutatiｏnｓｉnSａlmoｎeｌlaｂａcteｒiａ。

ａｍiｌｏride—sｅnｓｉtｉvesodiumchannelAsodｉuｍchannelimｐorｔaｎtｉnthｅdeｔectionｏfthetａｓteｏfsａｌt.Suchchａnnelsaｒeｉnhｉbitedbｙａｍiloridｅ，whicｈalsomｕtesthetasteｏfｓaｌｔ．

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aminoaciｄAnorganｉｃaｃidｗｉｔhanα—cａrbｏnａｔomlｉnkedｔｏacaｒbｏｘyliｃacｉd,aｎaｍiｎｏgrｏup,ahydrogenaｔｏm,ａndasｉdecｈａiｎ(ｔheRgｒｏup）.Ｔwentyｄｉfｆereｎtaｍinoａcidsａreｔhｅbｕildingblｏcksofpｒoteiｎs.

aｍinosuｇａrＡｓuｇaｒthatｃｏｎtaｉｎsａｎaminoｇroｕpｒatｈerthａｎaｈydroxyｌgroupatthｅC-２posiｔiｏn；thｅmostcｏmmｏｎaｍｉｎosugarsarｅglucosａmiｎeaｎdgaｌaｃｔosamiｎe.

amiｎoacyl-tRＮAAnａminoacｉdesｔerｏftｒaｎｓferＲNA.

aｍｉｎoａcyl-tRNAｓyｎtｈetaｓｅAnｅnｚymeｔｈaｔａctivａｔeｓaｎａminoaｃidａｎｄthenlｉnkｓittoｔranｓferＲNA．Alsoknｏwnａsaｎactivatinｇｅｎzyｍｅ，eａchａmiｎoacｙｌ－ｔRＮＡsｙnthetaseisｓpecificforapartｉcuｌaramiｎoacｉd.

ａminｏtｒaｎsfｅraseAclａssofｅnzｙmｅsthａttransfｅｒaｎα－aminogrouｐfromａｎα-aｍｉnｏaｃidtoａnα—ｋｅtoacｉｄ。Aｌsocａlleｄtrａｎｓaminaｓes.

ammoniｏteｌicCharaｃteristｉcofｏrｇａｎisｍsinｗｈicｈexcesｓaｍmoｎiａisdｉrectlｙsecrｅted;manyaｑｕａｔicａnimaｌsaｒeaｍｍｏniotelｉc。

AMP-dｅpendentproteinkinaseAｐroｔeinkinase,cｏｎｓeｒvedamongeuｋaｒyotｅs,thａtisaｃtiｖatｅdonbiｎdｉngoｆAＭPandｉnhｉbitｅdbyAＴP;coｎseqｕentｌy，itfuｎctｉonsａsaｃeｌluｌarfuelgauge,inhｉｂｉｔiｎgcerｔainproｃeｓsｂypｈｏsphorylatｉｎｇｋeyenzｙmeｓwhｅntｈｅenergｙsｕpplyisloｗ．

ａｍpereAｍeaｓｕreofｅｌectricａlｃurrｅｎt：theｆｌoｗof6.2４×1018ｃｈａrgesｐeｒsecond．

ampｈibolｉcreactiｏnsMｅtａbolicreaｃtionsthatcanbeaｎaboｌicorｃaｔaｂoｌｉc，dｅpendingonthｅenｅrgｙcｏｎｄitiｏnｓinｔheceｌl。

ampｈipatｈｉcmoleculeAｍolecule,ｓuchａsaｍembｒanelipid,thatcｏntaｉnsbothａhyｄrｏphobiｃａndahydｒｏphｉliｃmoｉety。

ａmyｌopeｃｔinThebraｎchedｆorｍoｆｓtａｒcｈ，ｃontaｉninggｌuｃｏsereｓｉduesｉnaｂoutoneα—１,6linkagｅperthirｔyα－1，4linkａges．

aｍylosｅTheunbranchedｆormofｓｔarch,containiｎｇgｌuｃoseresｉdueｓinα—１，4linkagｅ。

aｍｙtaｌAbaｒｂitｕrａteｔhatbｌocｋｓｔhｅreｓpirａtｏrｙchａｉｎｂｙiｎhibitiｎｇｅlectrontrａnsferintheＮADH—Qreductａsecｏmｐlｅx.

ａnabｏlicｓteroｉdAstｅｒoid,suｃhaｓtestoｓｔeｒone，thatactstｈroughtheanｄrogenreｃeｐｔorｔoｓtimulategeｎesｔhａtenhanｃethｅdｅveｌoｐmentofleanmusｃlemass。

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anabｏlisｍTｈeseｔofmetabｏlicrｅactionsｔhatrequiｒeenerｇytosynthｅizｅmolｅculesｆromsimplerpreｃursoｒs。

anａerobiｃIntｈeaｂseｎceｏfoｘygen.

ａnapｌeurｏticreactionＦrｏmtheGrｅｅkfor"filｌup，＂refｅｒringtoarｅacｔionｔhａtｒｅｐｌenisｈeｓｉntermｅｄiatｅｓremoｖedfromaｍetａboliｃｐaｔhway.Ｔhemostcoｍmonexaｍｐｌeistherｅactiｏnｃaｔａｌyzeｄbypyruvatｅcaｒboxｙlａｓe,ｉｎwhｉchtheｃarboxylａtioｎoｆpｙｒｕvaｔepｒoｄｕcｅsｏｘａｌoacｅtaｔe，akeycｏｍponentｏfｔhｅcitricacidcycle.

Ａndersen’sdiseasｅAdiseasｅduｅtｏaniｎabiｌitytointｒodｕcｅα-1,６－ｇlycosidicｂｏｎdsｄｕrinｇthesｙnｔhesiｓofglyｃｏgen.Glycogｅnispresenｔinnｏrmａｌamouｎｔｓbｕｔｗiｔhlｏｎgｏuｔerｂｒanｃheｓ；clinicａlly，theｄisｅaｓeischaｒacterizｅdｂyproｇｒeｓsiveｃiｒrhoｓisoftheliver。

anｄｒogensAｃlassofsteroidhｏrmoneｓ，exeｍplifiedbyteｓｔosterｏne,thaｔareｒespｏnsｉbleforthedeｖeｌopmenｔoｆmalｅsecoｎｄaryｓexualcharａcterｉｓticｓ；ｓyntheｓｉｚｅｄbｙｔheｔeｓteｓ.

anｇｓtroｍ（Å）Aunitoｆｌengthequalto１0-1０meter.

aｎｏｍｅｒsIsｏmerｓｏfcyclichemiaｃｅtalｓorhemikeｔaｌs,ｗｉtｈdｉｆfｅｒenｔcoｎfigｕraｔｉonsonlyaｔtｈｅcaｒｂｏnylcａrbonatom；thａｔｃarbonｉsknownａｓtheanｏmeｒｉｃcarboｎ.

aｎｔａgonistAｍoｌｅｃｕlethatbｉnｄsｔoareceptoｒproteinｂｕtdoesnottｒiggｅrｔｈesigｎalｉnｇpaｔhwａy。Sucｈmoleculｅsareｌiｋecompetｉtiveinhibitｏrsforｅnzymes。

aｎtiboｄyApｒoteｉｎsｙntｈesizedbｙａnaｎiｍaｌinresponｓetothepresenceｏfaforｅiｇｎsｕbsｔance，ｏraｎｔigen;oftenbｉｎdstotｈeantigen,ｎｅutralｉｚｉnｇitｏｒmaｒkingiｔforｄestruｃtion。

antｉcｏdｏnThree-nucleoｔiｄeｓeqｕenｃｅoftRＮＡｔｈatbase－pairｓwｉthaｃｏdoniｎmＲNA.

anｔigｅnAforｅiｇnsubsｔａｎｃｅthatelicitstｈｅｓyntｈesｉsofanantibody.

antiｇｅnicｄeｔerminantSｉteoｎanａntigeｎtｏwhichaｎantibodｙbinds.Ａlｓｏｃalledaneｐitope.

anｔimyｃｉｎAAnａnｔibioticfromSｔｒepｔoｍycesthatinhibitstherespiratｏｒycｈaｉnbyblockinｇeｌeｃtrontｒanｓferｉｎthecｙｔｏcｈｒｏmeｒeｄucｔasecomplｅx。

aｎtipｏrterAｔranｓporｔsystemｉnwhｉchamoｌeculeisｃarｒieｄaｃrｏssaｍembraｎeinｔｈediｒecｔiｏnoppoｓｉtｅthａtofａnion,wｈicｈinturnｉspｕｍpeｄbackaｃrosstheｍembｒanethrougｈａctivetranspoｒtｌinkeｄtoATＰｈyｄrolysiｓ。

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aｎtiserumSerｕmprｅｐａrｅdｆromtheｂlｏodｏｆaniｍmunｉzeｄanimalｃontainingｓolubleａｎtｉｂodiｅsｓpecifｉcforaｐａrticulａranｔigen。

apｏptoｓisＡcasｃaｄeofprｏtｅolytｉcenzymｅsthａｔresultｓincontｒolｌeｄcelldeathinreｓponｓetoｓｉgnificａntcｅlldaｍageorｓpｅcｉｆicdｅvｅｌopmentalpｒｏgrams.Alsocａlleｄｐroｇraｍmｅdcｅｌｌdeath．

aｒachｉｄｏnateDerｉｖedfromｌinoｌeate,a20:4fａttyａcidｔhａtｉsaｍａｊorprecｕrｓoｒtoseveralclａssesofｓiｇnａlmolecuｌes,ｉnｃｌudinｇｐroｓtaglａndiｎｓ．

arrestinAｐrotｅintｈａtplaｙsａｒoleintheterminatioｎofｔhevｉsuａlsｉｇｎal-traｎsducｔionpaｔhｗａyｂybiｎdiｎgtophosphorｙｌatedrhｏdopsiｎandｐreveｎtingfurtheｒinteractionwithｔranｓducｉｎ.Ａrrestｉnmaｙfunctioｎsiｍilarlyinothｅr7TM-depeｎdｅｎｔsｉgnａｌ-transdｕcｔionpathwａys。

asｃorbate（vｉtａminC)Awater－solubleｖitaminthatfunｃtionsaｓananｔioxｉdａnｔaｎｄｉsreｑuｉrｅdfｏrthehydrｏxｙlaｔioｎｏfcoｌlａgｅｎ；sｃuｒvyresultｓifａscｏrbateｉsｄｅficiｅnt。

aspａrtyｌproteａsｅｓＡclassofprotein-ｄeｇｒaｄingeｎｚyｍｅswhoseactｉvityisdｅｐendenｔｏnａnaspartaｔeresiｄueａttheactivesite.AnａspartｙlｐroteaｓeisｒeqｕiredｆorHＩVrｅｐｌiｃａｔｉｏn．

ATＰ(adenosinｅ5＇-tｒipｈosphate）Anucleotideconsisｔｉnｇoｆadenine,ｒibose，andｔriphosphateｕnitstｈａｔserveｓastheｃeｌlulareｎergｙcurｒenｃy.

ATＰ—ADPtranｓlocaｓeAｎadenｉnｅnｕcleｏtideｃaｒryinｇatransｐｏrｔｐrotｅintｈatcaｒriｅｓADＰｉｎtoｔｈemiｔochｏndｒiaanｄATPoｕｔiｎacoupleｄfaｓｈioｎ．

AＴP-binｄiｎgcasｓeｔｔe(ＡBC)dｏmａinＴｈeAＴP—binｄiｎｇｄｏmaｉnｃharacterisｔiｃofsｐecifｉcmｅmbrａnetransｐortｐroteｉnｓ,ｃalledAＢＣtranspｏrters；ｔhesｅtranｓpｏrｔersalsocontaｉnameｍｂraｎe-sｐanningｒegioｎ.

AＴP—graｓpfoｌｄAproteｉndｏmａｉｎｔhatsurroundsATＰaｎdorienｔsitfoｒｎucｌeoｐhiliｃattａｃkatｔhｅãpｈospｈate.Ｅnｚymｅswiththｅsedomaiｎｓcataｌyzetheformatioｎoｆcａｒｂoｎ—niｔrogenｂondｓthrｏughacylphosphａtｅiｎｔeｒmediａtｅs.

ATＰsynthaseMｏｌeｃularａｓｓｅmblyｏｆｔheｉnｎermｉtoｃhondｒiaｌmeｍｂranereｓpｏnsiblefortheｒｅspiraｔｏry－cｈａin-dｒｉvensynthｅｓisofＡTＰ.AlsocalledＣｏmｐlｅｘV,mｉtocｈondriaｌATPａse，Ｈ+—ＡTPａse，oｒF0F1-AＴＰａｓe．

aｔrａctyｌosｉdeＡpｌanｔglｙｃosidｅthａtinｈｉbitsＡTP—ＡDPｔrａnslｏｃａse．

atｔenuationInbａctｅria，ａmechａniｓmfoｒtrａnscrｉptioｎalregulatｉonｉｎwｈiｃhadｅcreaseiｎtｈeratｅｏｆtｒansｌaｔｉonoｆanmRNAopｅｒonrｅducestherａtｅｏftranscｒiｐtionofthatopeｒoｎ。

autoimmunediｓeａseAdisｅasｅ，suchａsinsuｌin-ｄeｐｅndentdiabetｅsandmｕltiｐlesｃlerosｉs，thatresｕlｔfｒomａfailuretosuppressｔhｅｉmmuｎeresponｓetosｅlf—ａｎtiｇens．

autoｒadiographyAmeａnｓｏｆdｅtｅctinｇraｄioａｃtｉｖｅmoｌeculesｉmｍｏbilｉzedinaseｐaｒatioｎｍediumsuchaspｏlyacrylamiｄe;ｔheraｄiｏactiｖitｙofｔｈｅmoleculeswｉlｌblackeｎx—rayｆilm.

aｕｔotｒophｓPhotoｓyntheｔiｃorｇanismsthａtsyｎｔhｅsｉｚｅｇlucosefｒomcarbondioxideａｎdwaｔer，byuｓingsunｌｉｇｈｔasanｅnergyｓouｒｃe;tｈｅglucoseisｔheｎusｅdasafuelfｏｒｃｅllulaｒmeｔaｂoｌism.

aviｄｉtｙThｅstrenｇｔhｏfaninｔeractiｏncomｐrisinｇｍultipleindependeｎtｂindinginｔeractｉonsbetweenpartners，aｓwoulｄtakeplａcebｅｔwｅenanantigenaｎdantibody．

axｏnemeTｈeｆｕnｄamentａｌdesignstｒuctuｒeoｆｃiliaandflaｇella；itcoｎsiｓtsofabｕndlｅofmｉcrotubuｌes,encloseｄinaｍeｍｂrane，inwhiｃhｎinｅmiｃｒｏtubuledoubletssurｒｏundtwomicｒotubulｅsｉｎglets．

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B

blymphocytｅＰrecuｒsoｒstoplaｓmacells，wｈichareａntiｂody－secｒeｔiｎgcelｌs。

bａcｉｔｒacinAnａｎtibiotiｃthatbloｃkstheｔｒanｓfeｒofｏｌiｇosａcchariｄesｆromdolichｏlpｈｏｓpｈａteｔoｐｒotｅins.

bacteｒioｒhodopsinA２6—ｋdintegralmｅmbraneprｏteｉntｈaｔabsｏrbslightａｎdconｖertsitｓｅnergyintoｐroｔon—moｔiveforｃｅ,ｗｈｉchisthenusｅdtｏｓyｎthesizeＡTP．

ｂase-ｅｘｃisionrｅpairAmeａnsｏfrepaiｒinｇDNAinwhicｈthedamageｄbaｓeisremoveｄandreｐlacedｂyaｂａｓｅcomｐlemeｎtａrytotｈeuｎdａmａgedDNAsｔraｎd．

B-ＤＮAhelixＡrｉｇht-handeddoublehｅliｘwithｔｈefollｏwingcｈaracteristicｓ:thetwｏstｒanｄsａｒeaｎｔipａrallel;ｔｈeｂａsesareinsidｅthehｅlｉxａnｄｔhｅｐhosphatesaｎｄdeｏxyｒｉbosesugarsareｏntｈeoｕtｓｉde；adenineformｓhydｒogeｎｂoｎdsｗiththyminｅ，ａｎdguａniｎeforｍsｔhｅｍwitｈcytｏsiｎｅ;thｅｂasesineachpaiｒarecoplanar;thereare10。４residueｓpertｕrn，wｉtｈapitchｏf35Å.

Ｂeｅｒ＇slawＴheｒelaｔionsｂetweenｔheabsorbaｎceofliｇht(Ａ)bｙacompoｕnd，itｓeｘtincｔioncｏefficienｔ(å)，conｃentｒａtｉon（ｃ）andthelengｔh（l）ofｔhｅligｈｔpatｈ:A＝åcｌ

bｅｒiｂerｉAｎeuroloｇiｃandｃａrｄiｏvasculaｒｄisordｅrcａｕseｄbyａｄietaｒydｅficiencｙｏfthiamｉnｅ(vitaminＢ1)．

βsｈeeｔAｃommonｓｔructｕralｍotiｆinｐrｏteiｎｓ，inwｈichtwoormoreβsｔrandsarｅaｓsociateｄasｓtacksofｃhaiｎs,sｔabiｌiｚeｄbyinterｃhaiｎhｙdroｇeｎbｏｎds;ａnumｂｅｒofβstｒａｎｄsrunningｉnｔｈｅsamｅdireｃtionfｏrｍaβpｌeatｅdsheet，whｅreａssucｈstrandsｒunningiｎｏｐpｏsitedirectｉonｓｆormanantipａralｌｅlpｌeateｄshｅet.

β－gaｌacｔosidaseＡnessentialenzyｍｅinlactoｓｅmｅtabｏlismthathyｄrolyzesｌactosｅintogalactｏseandｇlucose．

biｆｕｎｃｔioｎａlｅnzymeAnｅnｚｙmewithtwodiｆferent，oｆtenｏｐpｏｓinｇ，ｃataｌyticacｔivｉtｉｅsｏnonｅpolyｐeptidｅcｈain．Foｒinｓtaｎce，pｈoｓｐhofｒuctｏｋinase2synthesizesfｒuctose2,6－bisphosphａteanｄfructose2，６－ｂiｓphｏｓpｈatasehydrolyzeｓｉt,yｅtbｏthactiｖｅsitesａｒeonthesamｅpｏlypeptｉdechaiｎ.

bilesaltｓPolarｄerivatiｖesoｆcholestｅrｏlｔhatａrｅｍadｅｉnthｅliver，stoｒedinthegallbladｄer,andrｅleaseｄｉntotｈｅsmａllｉntｅstine,wheretｈeｙactａｓdetergｅｎtsｔosｏlubiliｚedieｔarylｉｐiｄｓ,ｆaｃilitatingtheiｒdigｅsｔｉｏnａｎdabsorptｉｏn.

ｂindinｇenｅrgyThefrｅeenergｙrｅleａsedinｔheforｍatiｏｎoftheweakiｎtｅractiｏｎsbetweｅnｅnzymeａndｓubstraｔe.

ｂioｐｔerinAcofactorfrｏmwhichtheelｅcｔrｏncarrｉｅrｔｅtｒaｈydｒobｉopterｉnisderiveｄ。

ｂiotｉnAｖitaminｔhaｔplaysarolｅｉncarboxyｌaｔionanddecａｒboxylationｒeacｔiｏｎs.

BｏhｒeffｅcｔＴｈｅoｂsｅrvatioｎmａｄebｙChristｉanＢｏhrthａtH＋andCＯ2ｐromｏtetherｅleａｓeｏfoxygenfrｏmoxyhｅmｏgloｂｉn。

bｏngkrｅkicacｉdＡｎantibｉoｔｉcthatｉnhibｉtstheａctioｎofATP－AＤPtｒanslocase。

bｒanchmigrａtioｎThｅaｂilityofaDNAsｔrandｐartlyｐaｉreｄwｉｔhitscomplementaryｓtraｎdtｏmoｖe，displａcｉnｇitsｈomologoｕsrｅｓｉdｅntstrandanｄexteｎdiｎgthｅｐａiring.

brｏmｏdomainAdomaｉnconｓｉsｔｉngofaｆｏｕr—helixbundletｈatbiｎdspeptideｓｃonｔainingacetyllyｓine.Ａlｓocallｅdanａcetｙllｙsinｅ－ｂｉndingｄomａin。

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ﻫC

C３plａｎtAplaｎtsthatlackstheC4pathway．

C4pａtｈwayAmeanｓbyｗhichfｏｕｒ－cａrｂoｎcompounds,suｃｈaｓｏxaloaceｔateanｄmａlate，ｃａrryｃarｂｏndiｏxidｅｆrommｅsophylｌcellsinconｔactｗiｔhthｅａirtｏbuｎdｌe-sheaｔhcells,whichaｒetｈemaｊorsiｔesofphotｏｓyntｈｅsiｓ。Thepathwａyacceｌeratespｈoｔosynthesisｂyconcentｒaｔingcarbｏndiｏxiｄｅinphotｏsyntｈeticcｅlls．

C4plantAplａnｔtｈａｔuｔilｉｚeｓtｈｅC4pathwaｙ．

CＡATｂoxAｃomponeｎtofmanyeｕkaryoticpｒomotｅｒswiｔhｔｈeconsensuｓsｅqｕenｃｅ5’—GNＣAAＴCＴ－3'．

CａlｃiuｍATPase（Ca2+ATPａsｅ)ＡnATP-drivenｃalciｕmpumpthatmaｉｎtainｓｔｈelargeｅlectrocｈeｍicaｌgｒaｄiｅnｔoｆcalcｉumｉonａcroｓｓｔｈepｌasmaｍembｒane。

calmoduliｎＩnveｒteｂrates，auｂiqｕｉtouｓprｏteiｎinveｒｔebｒatestｈat，whenboundtocａｌciuｍ，stimuｌateｓmaｎyenzymｅsaｎdｔransportｅrs.

cａlmodulin－dependentkinaseＡprotｅinkiｎasｅｔｈatiｓactivaｔedbythebｉnｄinｇofaＣa２+－ｃalmodulinｃomplex.

calnexｉｎＡncｈｏredintheendoｐlasmicreticuｌuｍｍembｒane，ａchaperonepｒotｅiｎｔhatpｒeventｓｔheｅxｐｏrtｏfimmatureoｒdefｅcｔｉｖeglyｃopｒoteinsbybindｉngglucoｓｅresidｕesonｔheglｙｃｏproteins.

caloricｈomeostasiｓＭａintｅｎａnceofａcｏnstanｔbodywｅighｔbyacompｌexnetｗorkofｈｏrmoｎａliｎteracｔions。

calｏrieＴheamounｔｏfheaｔｒequiredtoraiｓeｔhetemperａturｅof1gramofwａtｅrｆrｏｍ14．5°Ｃｔo15。5°Ｃ．

ＣａlvincｙcｌeInplants，ａcｙcｌｉcmeｔaｂolicpatｈwayinwhichcarboｎdｉoxｉdeisincorporaｔedintorｉbulose１,5—bisｐhoｓpｈatetｏgiｖｅcoｍpoundsｔhatcaｎbｅuseｄforｔhesynthesiｓoｆglucose。

5’ｃａpAstructｕreatthe5'eｎｄofeukaryoｔicmRNAｔhatsｔabilizesthemＲNAaｎdｅｎhａncesiｔｓtransｌatioｎ．Ｔhecapcontａｉnsa7—methyｌguaｎyｌａｔereｓiduｅaｔtａchｅdｂyａtｒiｐhosphaｔelinkagetｏthesugaratthe５’enｄｏfthemRNAｉｎarare5’—5'linkａge.

caｐsaicｉnreceptorsIonｃhanｎelsexpresseｄiｎnoｃｉｃeptorsthａtoｐeniｎreｓponsetonoxiousstiｍuliｓｕcｈasheａt，acｉｄitｙorcheｍicaｌssｕcｈascapｓaiｃin,tｈechemicaｌresponsｉbleforthｅ"hｏt”tasｔeofsｐicｙfood.Ａlsocalledtｈevanilloidreceptor1（VR1)。

cａｐsidＴhepｒｏteincoatsurroｕndiｎgviralDNAoｒRNＡ．

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carbａｍoｙｌｐhospｈatesｙｎｔhｅｔaseAnenzymeｔhatbeginｓthｅuｒｅacycleｂyｃatalyzｉｎgtheｓyntｈｅｓiｓofcａrbａmoyｌphosphateｆrombicarｂonａte,ammoｎiｕmion，andATP。Theｅｎｚymeａｌsocａtalyｚｅstheinitialreaｃtionｉnpyrimidiｎｅbioｓynthesis。

carboｈydratesSacchariｄes,whichaｒeaｌｄehｙdeｏrkeｔonecompoｕｎｄswitｈmｕltiｐleｈyｄroxylｇroups。Aｌsodｅfｉnedasorgaｎｉcｃomｐｏundsｗithｔｈeｅｍpiricaｌformｕｌa(ＣH２O)n.

carboniumiｏnAcarboｎcｏmpoｕnｄthａtｃｏnｔaiｎｓａpoｓｉtiveｌｙchａrgedｃarbｏnatom；ａcａrboniumatomiscritiｃalfｏｒcatalｙsisbyｌｙｓｏzyｍe

carｂoxyｌaｓｅＡnenzｙｍeｔｈatcaｔalyzｅsaｃarboxｙｌｔｒaｎsferreaction；biotinisusuaｌlｙrequｉreｄasaｃoｅnzyme。

caｒcinoembryonicanｔigen(CＥA)Ameｍｂraneglycoproｔeinofｔhefｅtaｌgasｔroinｔestiｎaｌｃellstｈａｔisnｏｔsiｇnificanｔlyｅxｐressedａfｔｅrbirth.HighserumｌeveｌsofCEAａｒeｅviｄentｉnmanypatｉeｎtswithcolorectａlcancer．

cardioｔoｎｉcsteroｉdsCompoundsdｅrｉvedfromchｏlesｔeｒoltｈatinhibittｈeNａ+-Ｋ+ｐｕmpbyblockinｇthedephosphoｒylaｔionｏfｔｈｅE2coｎformａtioｎｏｆtｈeｐuｍpproteｉn．Iｎhibｉtioｎofｔhｅｐumpincaｒdiactｉssｕeceｌlsleaｄstoahｉｇｈeｒlｅveｌoｆsｏdｉｕmioninｔhecelｌs，wｈichsloｗsthｅextrusionｏｆcalciumionaｎdｅｎhａncesｃarｄｉacmuｓclｅcoｎtracｔiliｔｙ。

carｎiｔinｅAzｗitｔｅrioniｃcomｐoundformedfromlyｓiｎethatactsasacarrｉｅroｆloｎg—ｃhainｆaｔtyａciｄｓｆｒｏmthecytosｏltotheｍitochondriaｌmａtriｘ．

caｒoteｎoｉdｓEｘtendｅdpｏlyeneｓtｈaｔaｂsorｂlightbetween４0０and5０0nmaｎｄsｅrvｅaｓacceｓｓorypiｇｍｅntsiｎphotｏsyｎｔhｅsiｓｂyfｕnneliｎｇthｅenerｇytoｔhephotosyｎtheticreaｃtioncenｔeｒ.

casｃade，ｅｎzyｍａticＡsequenceofｒｅactions,iｎｗhicｈateachstｅpａpｒoｄuctstiｍulateｓanｅnｓuｉｎgreacｔion,gｅｎｅrａtｉnganamplificaｔionｏfaｒeｌａtiｖｅlｙsmallstｉmuｌuｓorｓｉgnaｌ．

caｓpasesＣysteineｐroteasesthａtｐａｒｔiciｐatｅｉｎtheproteｏlｙｔiccasｃadeinapoｐｔosis.

ｃataｂolisｍTｈesetｏfmetaｂolｉcｒeactioｎｓｔｈattrａnsformfuelｓintocellulaｒｅｎｅrgy.

catabｏliteacｔivatoｒprotｅin(CＡP）TｈeｃＡMＰrｅsponｓｅpｒｏtein；ｗhenbouｎdtocAMP，CＡPbｉndstoaninｖeｒtedrepeａtedoｆtｈelａｃｏpｅroｎ,neａrposｉｔion－６１rｅlativetotｈestartsiｔeoftranscriptｉon,tostimulaｔetｒaｎscｒiption。

catａboliteｒｅpressionTherepｒｅssionbygｌucｏseoｆcataboｌicｅnzｙｍesrequｉｒedfｏrthecａｔabolisｍoｆcarbohydｒａteｓｏｔheｒthanglucosｅ.

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ｃatａlaｓeAubiqｕitｏushemeｐroteinｔhatcatalyzesｔhedismutationofhyｄｒogeｎpeｒoxideintｏmoleculaｒoxｙｇenanｄwaｔｅｒ．

cataｌysｉsbyapproｘｉｍatｉonＥnhａncingtherateｏfareａctｉonbybringiｎgmｕｌtipleｓubstrａｔeｓtogetheraｌｏngaｓinglebｉndｉｎgsuｒfaｃeoｆaｎeｎzｙｍｅ．

ｃatalyticantｉｂodiesＡntiｂodiesgeｎerａtｅｄｂyｕsｉngtｒansｉtｉｏn-stａteanaｌｏgsofａpａrticuｌarｒeacｔionａsaｎtigeｎｓ。Suchaｎtiboｄiesofｔenfunctｉoｎasｃatａlyｓtsｆoｒtｈereaｃtiｏn。Alｓｏcallｅｄabzymｅｓ。

catａｌyticｇｒｏupAnaminoacｉdorcofaｃｔorａtaｎenzymesａctiｖesiｔethatdirectｌypaｒticipateｓｉnthｅmaｋinｇorbrｅakingofcｏｖaｌｅｎtbｏnds．

ｃatalyticRNＡOneofａcｌａsｓｏfＲNＡmoｌeculｅstｈatdiｓｐlaｙenzｙｍａticａctivity.

cａtaｌｙｔictriａdＡcoｎｓtｅllationｏfthreerｅsiｄｕｅs，fｏundiｎmａnypｒｏｔeolyticenzymeｓ，inwｈiｃhtwooftｈｅresiduesconveｒttｈeremaiｎiｎgｒesidue，usuallyaseriｎｅoｒcｙsteine,inｔｏapoｔentnｕcleｏｐhile。

CD4ＡproteinpreｓｅntonthｅｓuｒfａceofｈｅlperTceｌlｓthat，ａloｎgwｉththeＴ－ｃellreｃｅptoｒ,bindsｔocｌａssIIＭHＣｐroteinｓｏnａntigｅn－prｅsｅnｔｉngcelｌs。CD４ｉsｔhesourceoｆthespecificｉｔyofhelperTcelｌsforclasｓIIMＨＣinｔeｒａctioｎs．

CD8Acｅll-suｒｆａｃｅproｔeｉnexpressedbｙｃytotoｘicTcelｌｓｔhａt,incoｎｊunctioｎwｉｔhｔｈeTcｅlｌrｅｃeｐtoｒ，reｃｏｇnｉｚeｓｃlassIMＨC-peptｉdecompleｘｅs。CD8biｎｄstotｈeMHＣproteiｎitｓｅlf．

cDＮAＤNAcｏｍplementａｒyｔoａnmRNAsequence．

CDP-ａlcoholActｉvａtｅdfｏｒmofanａｌcoholthatcａnｂｅusedｉntｈesｙnthesisoｆphosphｏｇlycerｉｄesｂyｃoｍbｉnｉｎgwｉｔhdiａcylgｌycｅroｌaｔtheｆｒeehyｄroxylｇrouponglｙcerol；forinｓtａｎce，ＣDP—cｈｏｌinecaｎreaｃtwithdｉａcylｇlyceroｌtoformtｈephｏspｈoliｐｉdphoｓphatidyｌcholiｎe。

CDP－diacｙｌglycerｏl（cytidｉnedipｈosｐｈｏdiacylglycerｏｌ）Fｏｒmedfｒomphosphａtidａtｅandcｙtiｄinetｒiｐhospｈate(CTＰ）;actiｖaｔedｄｉacyｌglyceｒoluseｄｉnｔhesyｎｔhesiｓofphosphoglyｃeridessｕchasphosphatidyｌserinｅ。

ceｌｌｔypeCeｌlswiｔｈｉnanoｒｇanｉｓmthathａｖetheｓamegenｅｔｉcｍakｅupbｕthaｖediｆfeｒentｐropｅrtｉesowiｎgtｏｄｉfferencesingenｅexｐrｅssioｎ．

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chimｅricＤNAＡrecomｂｉｎantＤＮAｍolｅcｕleconｔaｉningunrelatedgenｅs．

chｌoｒaｍpｈeniｃoｌAnaｎtiｂiotｉcthatinｈibitsthepeptｉｄyｌtransfeｒａsｅactivityofthepｒokａryｏｔic50Sｒibosomalsuｂunit。

ｃhlｏrophyllAsubstｉｔｕtｅdtetｒapyｒrolethａｔisｔheprinciｐａlphｏtorecｅpｔorinplants.

ｃｈloroplａsｔTheplaｎｔorｇanｅlleｉnｗhｉchphotｏsyntｈesistａkesｐlace。

cｈoｌeratoxinAtoxｉnthatｃonsiｓtsoｆacatａlyｔicｄoｍaiｎａndameｍｂrane-pｅｎetrａtｉondomain；ｔｈｅcataｌｙticｓubｕnitADP－riｂｏsylateｓtｈｅGstimulａｔoｒyｐｒｏteiｎ，persisteｎｔlyａｃtivatingit，lｅａdiｎｇtoaｃtivatｉonｏｆｉonpｕｍpsandｓubsｅquenteｆｆluxoflａｒgｅaｍｏunｔsｏｆＮａ+ａｎdｗaｔeｒiｎtｏｔｈegut.

ｃholestｅrolAstｅrolｔｈaｔisanimportａnｔｃｏnｓtituenｔofeukaryoｔｉｃmemｂraｎesaswellaslipoｐroteinｓ;alsoａpｒecuｒsorofstｅroｉdhorｍoneｓ.

cｈrｏmatinN