Ingabe ukusetshenziswa komoya-mpilo okwengeziwe kusho i-ATP eyengeziwe? Izifundo ezivela ocwaningweni lwe-methylene blue

I-mitochondrion ehlukanisiwe ifakwa egunjini lokuhlola elinomthombo wamandla kodwa elingenayo i-ADP. Isebenzisa umoya-mpilo kancane. Uma kufakwa i-ADP, ukusetshenziswa komoya-mpilo kwanda ngokuphindwe kaningana. Uma kulindwa kuze kuphele i-ADP, ukusetshenziswa komoya-mpilo kuyehla futhi. Umthombo wamandla awushintshanga. Okushintshile kuphela yisidingo se-ATP.

Lolu chungechunge olufushane lwezehlakalo luqukethe wonke umehluko okukhulunywa ngawo kulesi sihloko. Ukusetshenziswa komoya-mpilo kukala ukuthi ama-electron ageleza ngesivinini esingakanani ochungechungeni lokuphefumula kwamaseli aze afinyelele emoyeni-mpilo. Ukukhiqizwa kwe-ATP kukala ukuthi kungakanani kulokho kugeleza okugcinwa njengamandla asebenzisekayo. Kokubili kwabelana ngesinyathelo esiphakathi, igradiyenti yamaphrothoni ezinhlangothini zolwelwesi lwangaphakathi lwe-mitochondrion, futhi noma yini eshintsha indlela le gradiyenti ehlanganiswe ngokuqinile ngayo nokwakheka kwe-ATP ingenza le miphumela emibili iye ezinhlangothini ezahlukene. I-methylene blue isiza ukuqonda lokhu ngoba iye yabonakala yenza kokubili: yandisa ukusetshenziswa komoya-mpilo kanye ne-ATP kwamanye amasampula, futhi yandisa ukusetshenziswa komoya-mpilo kuyilapho i-ATP ingashintshi noma yehla kwamanye.

Abafundi abafuna ukuqala ngombono obanzi wokudluliswa kwama-electron bangafunda ngokuthi i-methylene blue iwathutha kanjani ama-electron ochungechungeni lokuphefumula kwamaseli, kanti abafuna ukuqonda amagama asetshenziswa ekuhloleni kwasekuqaleni komoya-mpilo bangafunda ngokuthi izilinganiso zokuqala zokuphefumula kwamaseli zabonisani ngempela.

Ukuphefumula kwamaseli, i-ATP, negradiyenti ephakathi kwakho

Ama-electron avela ku-NADH naku-FADH2 angena ochungechungeni ezakhiweni eziyinkimbinkimbi I no-II, adlule esakhiweni esiyinkimbinkimbi III aye ku-cytochrome c, bese edlula esakhiweni esiyinkimbinkimbi IV aye emoyeni-mpilo. Amandla akhishwa ezakhiweni eziyinkimbinkimbi I, III, no-IV ampompa amaphrothoni aphume ku-matrix aye esikhaleni esiphakathi kwezindwelwesi. Lokho kwehlukaniswa kweshaji kagesi nobumuncu yikona okwakha amandla aqhuba amaphrothoni, futhi ingxenye yakho kagesi, umehluko wamandla kagesi ezinhlangothini zolwelwesi, ngokuvamile iyona ebusa kakhulu.

I-ATP synthase ivumela amaphrothoni ukuba ageleze abuyele ku-matrix futhi isebenzisa amandla akhishwayo ukuhlanganisa i-ADP ne-phosphate kube i-ATP. Ngakho uchungechunge lumi kanje:

ukusetshenziswa komoya-mpilo, bese kuba ukupompa amaphrothoni, bese kuba igradiyenti, bese kuba ukwakheka kwe-ATP.

Inkinga ukuthi amaphrothoni angabuya ngezinye izindlela. Noma yikuphi ukubuya okudlula ngaphandle kwe-ATP synthase kuwukuvuza kwamaphrothoni. Ukuvuza kuphoqa uchungechunge ukuba lumpompe lawo maphrothoni futhi ukuze lugcine umehluko wamandla kagesi olw elwesini ungashintshi, okusebenzisa umoya-mpilo owengeziwe ngaphandle kokwenza i-ATP eyengeziwe. Ukuvuza okunamandla ngokwanele kuwukuhlukana kokuhlanganiswa: ukusetshenziswa komoya-mpilo kuyakhuphuka kuyilapho i-ATP ingashintshi noma yehla, futhi amandla achithekile aphuma njengokushisa.

Isimo 3, isimo 4, nesilinganiso sokulawulwa kokuphefumula kwamaseli

Amagama avamile alokhu avela ocwaningweni lwama-mitochondria ahlukanisiwe. Isimo 3 siwukuphefumula kwamaseli lapho kukhona i-substrate kanye ne-ADP: i-ATP synthase inciphisa igradiyenti, umehluko wamandla kagesi olw elwesini uyehla, uchungechunge lusheshise ukuze luyakhe kabusha, futhi ukusetshenziswa komoya-mpilo kuphakeme ngoba kwakhiwa i-ATP. Isimo 4 siwukuphefumula kwamaseli ngemva kokuphela kwe-ADP: i-ATP synthase ayisasebenzi kakhulu, igradiyenti iyakhuphuka, umehluko omkhulu wamandla kagesi olw elwesini uvimbela ukuqhubeka kokupompa, futhi ukusetshenziswa komoya-mpilo kwehlela ezingeni elidingekayo kuphela ukuze kunxeshezelwe ukuvuza.

Ngakho isilinganiso sokulawulwa kokuphefumula kwamaseli, okuyisimo 3 esihlukaniswe ngesimo 4, sibonisa ukuthi isampula ihlanganiswe ngokuqinile kangakanani. Isilinganiso esiphezulu sisho ukuthi i-ADP ilawula ukuphefumula kwamaseli ngamandla. Isilinganiso esehlayo kuyilapho isimo 4 sikhuphuka sisho ukuthi ukuvuza sekuqala ukubusa. Lona umbono osiza ukuqonda imiphumela ye-methylene blue engezansi.

Kunombono owodwa okufanele ukhunjulwe. Umehluko omkhulu wamandla kagesi olw elwesini unciphisa ijubane lochungechunge. Ukuwuhlakaza kuyalusheshisa. Uchungechunge lusabela ekutheni ukupompa sekunzima kangakanani, hhayi ngokuqondile ekutheni i-ATP iyakhiwa yini.

Lapho imiphumela ihambisana

Isibonelo esicace kakhulu sokuhlanganiswa sivela kuma-mitochondria obuchopho ezingulube zaseGuinea ahlukanisiwe, anezakhiwo eziyinkimbinkimbi zokuphefumula kwamaseli ezivinjiwe. Ku-100 nanomolar kuya ku-1 micromolar we-methylene blue, ukusetshenziswa komoya-mpilo ngesikhathi sokuphumula kwakhuphuka lapho kusetshenziswa i-glutamate kanye ne-malate, i-succinate, noma i-glycerophosphate njengomthombo wamandla, kuyilapho ukuphefumula kwamaseli okugqugquzelwa yi-ADP kungashintshanga. Kuma-mitochondria ayekhutshazwe esakhiweni esiyinkimbinkimbi I noma III, udayi wandisa ukukhiqizwa kwe-ATP kancane, wabuyisela umehluko wamandla kagesi olw elwesini, futhi wathuthukisa ukumuncwa kwe-calcium. Indlela ehlongozwayo iyisinqamuleli: udayi wamukela ama-electron ngaphambi kwendawo evinjiwe bese uwadlulisela ku-cytochrome c, weqa isakhiwo esiyinkimbinkimbi esilimele.

Isibonelo sesibili sokuhlanganiswa sisebenzisa umthombo we-ATP ohluke ngokuphelele. Kuma-mitochondria obuchopho ahlukanisiwe lapho i-ATP synthase ivinjiwe, i-methylene blue yayisagqugquzela ukuphefumula kwamaseli kuwo wonke ama-substrate ahloliwe. Kodwa ukwakheka kwe-ATP kwakhuphuka kuphela nge-alpha ketoglutarate ne-glutamate, ama-substrate amabili akha i-succinyl CoA. Njengoba i-oligomycin yayivimba i-ATP synthase, i-ATP eyengeziwe yavela ekufakweni kwe-phosphate ezingeni le-substrate yi-succinyl CoA ligase emjikelezweni we-citric acid, hhayi ekufakweni kwe-phosphate okuhambisana nokukhipha ama-electron. Udayi wabuye wabuyisela umehluko wamandla kagesi olw elwesini lapho isakhiwo esiyinkimbinkimbi I ne-ATP synthase kuvinjwe ndawonye. Lapha ukusetshenziswa komoya-mpilo ne-ATP kwahambisana, kodwa kuphela lapho i-substrate ivumela indlela yesibili yokwakha i-ATP. Nge-succinate noma nge-malate, ukuphefumula kwamaseli kwakhuphuka ngaphandle kwe-ATP eyengeziwe. Udayi ofanayo, igumbi elifanayo, umthombo wamandla ohlukile, impendulo ehlukile.

Lapho imiphumela yehlukana

Izimo zokwehlukana nazo zishicilelwe futhi zifundisa ngendlela efanayo. Ocwaningweni lwango-1997 lwama-mitochondria esibindi samagundane ahlukanisiwe, i-methylene blue yasheshisa ukuphefumula kwesimo 4 kuma-mitochondria ahlanganiswe ngokuqinile ayesebenzisa i-succinate, okwehlisa isilinganiso sokulawulwa kokuphefumula kwamaseli. Umphumela wawubonakala kusukela ku-0.5 micromolar futhi wawunamandla ku-5 micromolar, okuyizinga lokugxila eliseduze namazinga ku-plasma ngemva kokufakwa ngomthambo okukodwa kwe-100 milligram. Ku-5 micromolar ama-mitochondria nawo avuvukala, nakuba inkinga yokuhlanganiswa yaqala ukubonakala emazingeni aphansi okugxila, okusikisela ukuthi ukuvuza kwandulela ukulimala kwesakhiwo kunokuba kuvele ngenxa yakho. Kuma-mitochondria angahlanganisiwe, udayi wagqugquzela ukuphefumula kwamaseli ngendlela eyayincike ekugxileni futhi eyayifinyelela emkhawulweni. Ukusetshenziswa komoya-mpilo kwakhuphuka kuwo womabili amasampula. Ukwakheka kwe-ATP ngomoya-mpilo ngamunye osetshenzisiwe akuzange kukhuphuke. Lokho kuwukuhlukana kokuhlanganiswa okuvamile kanye nokuthuthwa kwama-electron, ku-molecule eyodwa.

Ukwehlukana okuphawuleka kakhulu kuvela ku-retina. Emagundaneni antula i-AIF nasemaselini amukela ukukhanya aphathwe nge-rotenone, i-methylene blue yagcina ubukhulu be-retina, izimpawu zamaseli amukela ukukhanya, nesakhiwo sama-mitochondria, futhi yehlisa isilinganiso se-NADH ne-NAD yanciphisa nokusebenza kwezindlela zokuphendula ekucindezelekeni, okuhlanganisa impendulo kumaphrotheni angasongekile nokususwa kwama-mitochondria nge-mitophagy. Yakwenza lokhu ngaphandle kokulungisa ukusilela kwe-ATP. Ukuvikelwa ngaphandle kokubuyiselwa kwamandla kusho ukuthi inzuzo yayidlula ekulinganiseni ukusabela kokudluliselwa kwama-electron nasekugcineni ubuqotho bama-mitochondria, hhayi ku-ATP eyengeziwe. Noma ubani olinganisa ukusinda kwezicubu nokubuyiselwa kokukhiqizwa kwamandla angakuqonda kabi ngokuphelele lokho kuhlola.

Ucwaningo lwama-mitochondria obuchopho lwengeza uhlangothi lwezindleko kulowo mfanekiso. Wona lawo mazinga aphansi okugxila athuthukisa izinqubo zamandla eziphilayo aphinde andisa ukukhiqizwa kwe-hydrogen peroxide kuzo zonke izimo ezihloliwe futhi anciphisa ijubane lokususwa kwayo, njengoba kwakalwa ngokuhlola kwe-Amplex okulinganiselwe, hhayi ngodayi ongakhethi into ethile kuphela. I-ATP eyengeziwe nento ekhipha ama-electron eyengeziwe kwafika ndawonye.

Uhlu oluwusizo lokuhlola lapho kufundwa

Imibuzo emine yehlukanisa umphumela ohlanganisiwe kongahlanganisiwe.

Owokuqala, yimuphi umphumela owakalwa ngempela. Ukusetshenziswa komoya-mpilo kukodwa akukwazi ukubonisa i-ATP. Ukwakheka kwe-ATP, umehluko wamandla kagesi olw elwesini, nesilinganiso sokulawulwa kokuphefumula kwamaseli ngakunye kwengeza ingxenye i-electrode yomoya-mpilo engakwazi ukuyibona. Umhlahlandlela wokufunda izimangalo zocwaningo lwe-methylene blue uchaza kabanzi lokhu kuqaphela ukuthi yimuphi umphumela okaliwe.

Owesibili, iyiphi i-substrate eyanika ama-mitochondria amandla. Umphumela we-succinyl CoA ubonisa ukuthi ukukhethwa komthombo wamandla kunganquma ukuthi ukuphefumula kwamaseli okwengeziwe kungaba yi-ATP eyengeziwe yini nhlobo.

Owesithathu, yiliphi izinga lokugxila elasetshenziswa. I-methylene blue emazingeni e-nanomolar kuya kwaphansi e-micromolar kuma-mitochondria obuchopho yanikeza ukuthuthuka okuncane ezinqubweni zamandla eziphilayo, kodwa kwaba nezindleko zokwanda kwezinto ezikhipha ama-electron; ingxenye ye-micromolar nangaphezulu kuma-mitochondria esibindi yenza buthaka ukuhlanganiswa; i-5 micromolar yengeza ukuvuvukala. Izinga lokugxila liyingxenye yendlela yokusebenza, hhayi imininingwane eseceleni.

Owesine, yiluphi uhlelo lokuhlola olwanikeza umphumela. Ama-mitochondria ahlukanisiwe aveza indlela izingxenye ezixhumene ngayo, kodwa amaseli nezicubu eziphelele zengeza ukuthuthwa kwezinto, ukwamukelwa kwama-electron okuguqula udayi ube yisimo esingenambala, nezindawo ezincintisanayo ezamukela ama-electron. Umsebenzi wokuhlola amanani asetshenziswa elabhorethri, okuhlanganisa nokuthi izinga lokugxila nenqubo yokuhlola kuyilolonga kanjani imiphumela ye-methylene blue, uyibhuloho eliphakathi kwezinombolo zasegunjini lokuhlola nanoma yisiphi isimangalo ngomuntu.

Ukusetshenziswa komoya-mpilo kubonisa ukugeleza kwama-electron. I-ATP ibonisa ukuthi kungakanani kulokho kugeleza okwagcinwa. I-methylene blue ingashintsha noma yikuphi kwalokhu, futhi ukuhlola okungenhla kubonisa zonke izinhlanganisela ezine ezilandelayo: kokubili kuyakhuphuka, ukuphefumula kwamaseli kukhuphuka kuphela lapho i-substrate ikuvumela, ukuphefumula kwamaseli kukhuphuka kuyilapho ukuhlanganiswa kwehla, futhi izicubu ziyagcinwa kuyilapho i-ATP ingashintshi. Inombolo eku-electrode yomoya-mpilo iyisiqalo sokuchaza umphumela, hhayi isiphetho salokho.