19.4 Oxidative Phosphorylation PDF

Preview

Summary

Download 19.4 Oxidative Phosphorylation PDF

Description

OXI DATI VEPHOSPHORYLATI ON Chapt er19Par t4of4 METABOLI CPOI SONS METOBOLI CPOI SONS Muc hofourknowl edgeofmi t oc hondr i alf unc t i onr es ul t sf r om t hes t udyof t ox i ccompounds . Spec i fi ci nhi bi t or swer eus edt odi st i ngui sht heel ect r ont r anspor ts y s t em f r om t hephos phor y l at i ons y s t em andhel pedt odefinet hes equenceof r edoxcar r i er sal ongt her es pi r at or yc hai n.

i fi nhi bi t ed,NADHwon’ tbeoxi di z ed. I ft hechai ni sbl ockedt henal lt hei nt er medi at esont hesubst r at esi de oft hebl ockbecomemor er educed,whi l eal lt hoseont heoxygensi de becomemor eoxi di z ed I ti seas yt os eewhathashappenedbec aus et heox i di z edandr educ ed c ar r i er sof t endi fferi nt hei rspec t r al pr oper t i es .I fav ar i et yofdi ffer ent i nhi bi t or sar eav ai l abl et henmanyoft her es pi r at or yc ar r i er scanbepl aced i nt hec or r ector der . Di ffer i ngs pect r alpr oper t i esdependonaci ds t r engt h. COUPLI NG r ef er st ot hef actt hatphos phor y l at i oni st ot al l ydependenton el ect r ont r anspor tandvi c ev er s a.Thet wopr oces sesar et i edt oget her i ndi r ect l yv i at hepr ot ongr adi ent-madebyel ec t r ont r ans por tandr equi r ed f orox i dat i v ephosphor y l at i on.

Et cr edoxr xnsc oupl edbyATPs y nt has ephosphor y l at i onr x ns I nhi bi t or sofel ect r ont r ans por ts t opt hefl owofel ect r onst hr ought he s y s t em.

s t opt heETCandev er y t hi ngst ops( r educ esact i v i t y) Bybl oc ki ngt hewayf orel ect r onst opas st ooxy gen,pumpi ngofpr ot ons s t ops .Thus ,s t oppi ngel ec t r ont r ans por tal s os t opsox i dat i v e phos phor y l at i on. Ther ear es ev er aldi s t i nctt y pesofpoi sonwhi c hmayaffec tmi t ochondr i al f unct i on.Wewi l lconsi dert hr eeoft hem:  Respi r at or ychai n( el ect r ont r anspor t )i nhi bi t or s  ATPsynt hasei nhi bi t or s  Uncoupl i ngagent s ETCI NHI BI TORS ETSi nhi bi t or sbi nds omewher eont heel ect r ont r anspor tchai n,pr ev ent i ng el ect r onsf r om bei ngpass edf r om onecar r i ert ot henex t . ETSi nhi bi t or sacts pec i fi cal l y( eachi nhi bi t orbi ndsapar t i c ul arcar r i eri nt he ETS) . I nt hi sc l as s ,we’ l ls t udyt hef ol l owi ngETSi nhi bi t or s : • Rot enone( Compl exIi nhi bi t or ) • Ant i myci n( Compl exI I Ii nhi bi t or )

• Cyani de( Compl exI Vi nhi bi t or ) • Car bonmonoxi de( Compl exI Vi nhi bi t or ) notal l ,onl yt al ki ngaboutsome • Rot enone Rot enonei nhi bi t sCompl exI

Rot enonei sanat ur al l yocc ur r i ngc hemi calf oundi nt her oot s ,s eeds ,and l eav esofs ev er als ubt r opi calpl ant sandhasbeencommonl yusedasa pi s c i c i deandi ns ect i c i de. Fi s hki l l er( pi sc i c i de)

Fi s har epar t i cul ar l ys ensi t i v et or ot enonebec aus et hechemi cal compound eas i l yent er st hei rbl oods t r eam di r ect l yt hr ought hei rgi l l s . I ndi genousfi s her shav et r adi t i onal l yc r ushednat i v er ot enonec ont ai ni ngpl ant sandappl i edt hem t omar i neandf r es hwat ert ocat chfi sh.

Fi s her mens mashbar bas cor oot swi t hapi ec eofwood,t hendi pandshak e t hesmas hedr oot si nt hewat er ,r el easi ngr ot enone.Poi sonedfi s hcomet o t hesur f ace,eas yt ot ak ewi t hanet . Lar gequant i t i esofr ot enoneof t enus edt ok i l l offi nv as i v eorunwant ed fi s hesi nf r es hwat ers y st ems ,t henr es t ockt hes y s t em wi t hnat i v efis ht o c ons er v et henat ur alecos y s t em ort osuppor tr ecr eat i onalfi sher i es .

Humansar ebel i ev edt obef ai r l ysus cept i bl et or ot enone.Howev er ,no humanf at al i t i eshav ebeenr epor t ed,per hapsbecauser ot enonei sus ual l y s ol di nl owconc ent r at i onsandbec aus ei t si r r i t at i ngact i oncaus espr ompt v omi t i ng. Rot enonei sr api dl ybr ok endowni ns oi landi nwat er .Thehal f l i f ei nbot hof

t hes eenv i r onment si sbet weenoneandt hr eeday s .Bec aus eofi t ss hor t hal f l i f eandbecaus ei tdoesnotr eadi l yl eac hf r om s oi l ,i ti snotexpec t edt o beagr oundwat erpol l ut ant . Bl oc ki ngCompl exIdoesnot c ompl et el ys t opt heETC becaus eel ec t r onc ans t i l lfl ow f r om FADH t ocompl exI I . 2 Effect sofCompl exI i nhi bi t or s: + I ncr easei nNADH/ NAD r at i o Decr easei nO 2 consumpt i on Decr easei nATPsynt hesi s bcl esspr ot onsbei ng pumped. Mor eNADHt hanNAD+ Rot enonebl ockscompl ex1 • Ant i myci n Ant i my c i ni smet abol i t epr oduc edbySt r ept omy cesbact er i a.I ti sc l as si fi ed asanext r emel yhaz ar douss ubs t anc e,andi ss ubj ec tt os t r i ctr epor t i ng r equi r ement sbyf ac i l i t i eswhi c hpr oduce,s t or e,orusei ti ns i gni fic ant herfi s hki l l er . quant i t i es .Anot

Ant i my c i nAi st heac t i v ei ngr edi enti npi sc i c i desus edi nfi sher i es management . Byi nhi bi t i ngcompl exI I I ,el ec t r onsc annotfl owf r om nei t herNADHand set obl ockcompl ex3t han2bcacc um ofNADH FADH ox i dat i on.Wor 2 andFADH2?? Becaus et hewor koft heETCi sdecr eas ed,t hecons ump4onofO i s 2 dec r eas ed. Al so,i ft hepr ot ongr adi enti snotf or med,t heATPs y nt hes i si sdecr eas ed.

Effect sofCompl exI I Ii nhi bi t or s: + I ncr easei nNADH/ NAD r at i o I ncr easei nFADH / FADr at i o 2  Decr easei noxygenconsumpt i on  Decr easei nATPsynt hesi s

• Cyani de Cyani dei nhi bi t sCompl exI V

Cy ani dei sanex t r emel yeffec t i v er ev er si bl ei nhi bi t orofc y t oc hr omeox i das e. Aconc ent r at i onof1mM KCNi ss uffic i entt oi nhi bi toxy genc ons umpt i onby mi t ochondr i af r om av er t ebr at es our ceby>98%. Cy ani dei soneoft hemos tdeadl ycompoundsi nal abor at or y .St ock soft he dr yc hemi cals houl dbes t or edunderl oc kandk ey .Becaus eofi t sv ol at i l i t y , ex pos ur et of umesf r om l ar gequant i t i esi shaz ar dous . I nt ox i cat i onbyc y ani dec anbeseenr el at i v el yf r equenti npat i ent swi t h s mok ei nhal at i onf r om r esi dent i alori ndus t r i al fi r es .( bur ni ngof pol y ur at hane)

3+ Cy ani depr i nc i pal t oxi c i t yder i v esf r om t hebi ndi ngt ot heFe i nt heHeme gr oupsi nCompl exI V,i nhi bi t i ngt hef unct i oni ngoft heEl ect r onTr ans por t Chai n. Asacons equence,r edoxr eact i onsi nt her es pi r at or yc hai nwi l ls t op,ener gy wi l lnotber el eased,pr ot onpumpswi l l notf unct i on,s ot heywi l l notr et ur n V,andt hepr oduc t i onofATPwi l lc ease. t hr oughCompl exI I nt ent i onal poi s oni ngcanbes eeni nsui ci dalper sonswi t hacc es st o c y ani decompounds . I nhi bi t or sofcompl exI V( l as ts t ep)ar et hemos teffec t i v ei nhi bi t or s. Thei reffect i v enessi saf unct i onoft hef actt hatt her ear eNO way sar ound t hei ri nhi bi t i on. Rot enone,whi c hi sani nhi bi t orofCompl exI ,i snotnear l yaspoi sonousas c y ani de,bec aus eel ec t r onsc ans t i l lfl owf r om FADHt hr oughCompl exI I . 2 • Car bonmonoxi de Car bonmonoxi dei nhi bi t sCompl exI V

Car bonmonox i dei nt ox i c at i onc aus esi mpai r edoxy genDELI VERYand UTI LI ZATI ONatt hecel l ul arl ev el . Theaffini t yofHbf orCO i sal mos t300t i meshi ghert hanf orOxy gen. I ti sc ol or l essandodor l es s ;hi ghl ev el sc anr esul tf r om i nc ompl et e c ombus t i onoff uel s :engi neandf ur naceex haus t sar ei mpor t ants our ces . Car bonmonox i dei sr es ponsi bl ef ormor et han50% ofdeat hbypoi s oni ng wor l dwi de. Thebr ai nandt hehear t ,t hathasahi ghox y genc ons umpt i on,ar et hemos t affec t ed. My ogl obi nhasev enagr eat eraffini t yf orCO t hanHemogl obi n. Asacons equenceoft hebi ndi ngofCO t ot hes emol ec ul es ,t hehear t f unct i oni ngi sv er yi mpai r edandt hepat i entpr es ent ss ev erhypot ens i on. I nhi bi t onofCyt oc hr omeOx i das e( compl exI V)byCO al s opl ay sar ol ei n CO i nt ox i c at i on. Hughaffini t yf orHbandMb.bi ndi ngt oHbandMbar emor er el ev anti n i nhi bi t i on. * * * need2know cyani dei scompl ex4( notgoi ngt ogi veusi nf ol i ke t hat )shoul dknow whatcompl exal lt hei nhi bi t or sbl ock. * * * effect s,degr eeofsever i t y;know whateachcompl exdoes.

ATPSYNTHASEI NHI BI TORS • Ol i gomyci n Ol i gomy c i ni nhi bi t sATPs y nt hase. Bi ndst oF0( notcat al yt i cs i t e)ofATPs y nt has e. ATPs y nt hes i sdec r eas eswi t hacc umul at i onofpr ot onsi ni nt er membr ane s paceul t i mat el yaffect i ngt hefl owofel ect r ons . Ac cumul at i onofr educedf or m ofe-c ar r i er s . Consumpt i onofO2r educ ed. * * * * * * * know wher ei ti nhi bi t s

Ol i gomyci nbi ndst ot heF subuni toft heATPsynt hasebl ocki ngt he 0 pr ot onflow. Theconsequencei st hatATPsynt hesi sdecr easeswi t han accumul at i onofpr ot onsi nt hei nt er membr anespaceul t i mat el y affect i ngt heflow ofel ect r ons. Thepr ot onpumpsoft heETC( compl exI ,I I I ,andI V) ,becomeunabl et o oper at ebecauset hegr adi entbec omest oos t r ongf ort hem t ooper at e. NADHi st hennol ongerox i di z edandt hec i t r i cac i dc y c l ec eas est ooper at e + becaus et heNAD c oncent r at i onf al l sbel owt hec onc ent r at i ont hatt hes e

enz y mecanuse. Ox y genc ons umpt i onwi l ldec r eas e. Whent heflowofpr ot onsi nt ot hemat r i xt hr oughATPs y nt has ei sbl ock ed, nopat hexi s t sf ort her et ur nofpr ot onst ot hemat r i x ,andt hecont i nued ex t r us i onofpr ot onsdr i v enbyt heact i v i t yoft her es pi r at or yc hai ngener at es al ar gepr ot ongr adi ent . Thepr ot onmot i v ef or cebui l dsupunt i lt hec os t( f r eeener gy )ofpumpi ng pr ot onsoutoft hemat r i xagai ns tt hi sgr adi entequal sorex c eedst heener gy r el eas edbyt het r ans f erofel ec t r onsf r om NADHt oO .Att hi spoi nt 2 el ect r onfl owmus ts t op;t hef r eeener gyf ort heov er al lpr oc es sofel ect r on fl owc oupl edt opr ot onpumpi ngbec omesz er o,andt hes y s t em i sat equi l i br i um. UNCOUPLI NG AGENTS ETCcanwor kwi t hATPsynt hesi s.How?Assumi ngyouar t i fici al l y cr eat eapr ot ongr adi ent . Ther ei sex per i ment alev i dencef orc hemi os mot i cc oupl i ng. Whent hephysi calcont i nui t yoft hemembr anei si nt er r upt ed,( f or exampl ebysoni cosci l l at i on)t her esul t i ngpar t i cl escancar r yout el ect r ont r anspor tbutnotATPsynt hesi s.

I nt he1940s ,i twass howns howt hatacompoundc al l eddi ni t r ophenol ( DNP)c ompl et el ybl oc k edt hes y nt hes i sofATPwi t houti nt er f er i ngwi t h ox i dat i on.NADHandFADH2

El ect r ont r anspor tandATPs y nt hes i sc anbeex per i ment al l ys epar at edf r om oneanot her . Socal l edUNCOUPLI NG AGENTSal l owt heobs er v at i onofel ec t r on t r ans por twi t houtATPs y nt hes i s . Ont heot herhand,ATPs y nt hes i swor k swi t houtel ect r ont r anspor ti fa pr ot ongr adi enti scr eat edi ns omeot herway . hephenol i chydr oxy lgr oupi nDNPi ss uc ht hati ti snor mal l y Thepk oft a di s s oc i at edatphy s i ol ogi c alpH.

DNPcandi ffus eac r os smembr anesi nbot hi t spr ot onat edand unpr ot onat edf or m. WhenaDNPmol ec ul eappr oac hest hei nnermembr anef r om t heout s i de,i t becomespr ot onat ed,bec aus eoft hel owerpHv al uei nt hi sv i c i ni t y .

Thi spr ot onat i oni nc r easest hehy dr ophobi ci t yofal l owi ngt odi ffus ei nt o mat r i xbymassac t i on. Oncei nsi det hemat r i x ,t hehi gherpHc aus est hehy dr oxy lphenolgr oupt o depr ot onat e. Mi t oc hondr i al mat r i xAtt opofpi cIt hi nk .I nt er membr anespac eat bot t om. Las tmol ecul e( onr i ght )depr ot onat es( dumpspr ot on) . i npr ot onat edf or m,canc r os si nnermembr ane( di ffus i on) + ThusDNPhast heeffectofTRANSPORTI NG HBACKI NTO THE MATRI X,bypassi ngt heF pr ot onchannel ,andt her ebyPREVENTI NG 0 ATPSYNTHESI S.

+ DNPi sanuncoupl erbec ausei twor k sasanH f ac i l i t at eddi ffus i onc ar r i er . di etpi l l s ! ! !Ox i dat i onoff ueldoesn’ ts t op.ATPj ustnotr el eased? El uc i dat i ng( mak esomet hi ngcl ear / ex pl ai n)t her ol eofDNPi nuncoupl i ng ox i dat i v ephos phor y l at i onwasaness ent i alc omponenti ns uppor tofPet er Mi t c hel l ' schemi os mot i chypot hes i s . + DNPs hor t c i r c ui t st heH gr adi entbef or ei tcanpasst hr ought he + F ATPas e,t husuncoupl i ngel ect r ont r anspor t ,t heener gys our c ef ort heH 1 gr adi ent ,f r om ATPs y nt hesi s . Ther ef or e,i nt hepr es enc eofDNP,el ect r ont r ans por tcont i nues ,butATP pr oduc t i oni sdi mi ni s hed.Theener gyt hatshoul dhavebeenconver t ed t ochemi calener gyi nt hef or m ofATPi st henr el easedasheat . Thei nnermi t oc hondr i almembr anecont ai nsuncoupl i ngpr ot ei ns( UCP) ( t her mogeni n) .Hi ghl yr egul at ed

pr ot ongr adi entaf or m ofener gy Unc oupl i ngpr ot ei nsar er egul at edmembr anepr ot ei nst hatpassi vel y t r anspor tpr ot ons,al l owi ngt hem t oby passATPs y nt hase. Anuncoupl i ngpr ot ei ni scapabl eofdi ssi pat i ngt hepr ot ongr adi ent gener at edbyt heETC.

El ect r ont r anspor tandhydr ogenoxi dat i onwi l lcont i nue,butATP synt hesi swi l lcease. Theener gyl os ti ndi ss i pat i ngt hepr ot ongr adi entv i aUCPsi sNOTusedt o dobi oc hemi calwor k . Theener gyt hatwoul dhav egonei nt oATPs y nt hes i si ss i mpl ydi ss i pat edas HEAT

Uncoupl i ngpr ot ei nsar ef oundi npar t i c ul ar l yhi ghc oncent r at i oni nt he mi t ochondr i aofBROWNADI POSETI SSUE,whi c hdi ffer sf r om t hemor e abundantwhi t eadi pos et i s suebyi t shi ghdens i t yofmi t ochondr i a.

t hebr ownf atc el l shav emanymor emi t oc hondr i a Thef unct i onofbr ownadi pos et i s suei st oconv er tener gyf r om f oodi nt o heatwi t houtATPpr oduc t i on. Br ownadi pos et i s suei sauni quel ymammal i ant i s suet hatpr ot ect s oundt het i meofbi r t hbycombust i ng neonat albodyt emper at ur ear t r i gl y c er i desi nt henumer ousmi t ochondr i at oemi theat( t her mogenes i s) . UCP1i sf oundpr i mar i l yi ndepot sofbr ownadi poset i ss ue,not abl y per i aor t i c ,c er v i cal ,i nt er s capul ar ,andper i r enal ,i nt hehumani nf ant .

I nadul thumansbr ownadi pos et i ss uei sf oundi nt hec er vi c al – s upr ac l av i c ul arar ea.Di mi ni s hesaswe’ r eol der .

BATmassdecl i nessi gni fic ant l ywi t hage.Howev er ,t hedec r easei nBAT masswi t hc hr onol ogi c alagemostl i k el yr eflect sl ongt er m di sus eoft hi s t i s sue,bec auseani mal sar et y pi cal l yhousedatt her moneut r al t emper at ur es .

Thi ss ugges t i oni sc onsi s t entwi t ht heobs er v at i ont hatcol dex posur eofol d r at sat10° Cf orfi v ec ons ec ut i v eday ssi gni fic ant l yi nc r easesbr ownf at massandBATcel ls i z e.

J us tl i k eUCP1doesi nbr ownf att i ss ue,di ni t r ophenol wi l l i nduc et he bur ni ngoff atorot hers ubs t r at esandt hepr oduc 4onofheat —buti nt he mi t ochondr i aev er y wher e,notj usti nbr ownf att i ss ue. Thi spr oper t yl edt ot hemedi cal appl i cat i onofDNPt ot r eatobesi t yf r om 1933t o1938. Uponaddi t i onofDNP:

•Thepat i entbec ameweakduet ol owATPl ev el s . •Br eat hi ngi ncr easedduet oi ncr eas edel ect r ont r anspor tt or es c ueATP pr oduc t i on. •Met abol i cr at ei nc r eas ed. •Bodyt emper at ur ei nc r easedduet oi nabi l i t yt ot r apel ect r i c alener gyas c hemi c al ener gyi nt hef or m ofATP,r el eas i ngheat . •Bodywei ghtdec r easedduet oi nc r easedr espi r at i onbur ni ngmor es t or ed f at . DNPwasi ndeedas ucc ess f ulwei ghtl os sdr ug. DNP,howev er ,di dhav eonedi st ur bi ngsi deeffect —deat h! edbyal ackofATP,butr at herbyadanger ous Fat al i t ywasnotcaus i nc r easei nbodyt emper at ur e( hy per t her mi a) . I nhumans ,20–50mg/ k gofDNPcanbel et hal . Al t houghgener alus eofDNPi nt heUni t edSt at eswasdi sc ont i nuedi n 1938,i ti ss t i l lempl oy edi not herc ount r i esandbybody bui l der st oel i mi nat e f atbef or ecompet i t i ons . ENDOFCHEM221FALL2018 NOTonfinal -Car bohydr at es -Li pi ds -Membr anes -Dr awi ngofmol ecul arst r uct ur es -I dent i f yst r uct ur es -Wat erspeci ficsl i keHydr ogenbondsandot heri nt er mol ecul ar f or ces -Gl uconeogenesi s -Essays Know f orfinal -pH,pKAofAAs -pr ot ei ns,enz ymes -Hb,Mb -Del t ag,ki net i cs -Bi oener get i cs* * * *st andar df r eeener gyIt hi nk? -Know namesofenz ymesandi nt er medi at es -Gl ycol ysi sandr egul at i on

-Pyr uvat edehydr ogenasecompl ex -Ci t r i caci dcycl e( gener al ) -Ch.19?s( notasspeci fic)BI G pi ct ur est uff Fort hi sch19Test4 -Know how subuni tCl ooks...