Ngaba ukusetyenziswa kweoksijini okungakumbi kuthetha i-ATP engakumbi? Izifundo ezivela kuphando lwe-methylene blue

I-mitochondrion ekhutshiweyo kwiseli ikwigumbi lovavanyo elinesibaso kodwa elingenayo i-ADP. Isebenzisa ioksijini ngokucothayo. Xa kufakwa i-ADP, ukusetyenziswa kweoksijini kunyuka ngokuphindaphindiweyo. Xa kulindwa de iphele i-ADP, ukusetyenziswa kweoksijini kuyehla kwakhona. Isibaso asitshintshanga. Kuphela yimfuno ye-ATP etshintshileyo.

Olo landelelwano lufutshane luqulethe wonke umahluko eli nqaku elithetha ngawo. Ukusetyenziswa kweoksijini kulinganisa isantya ezihamba ngaso ii-elektroni kwikhonkco lokuphefumla ukuya kwioksijini. Ukuveliswa kwe-ATP kulinganisa ukuba kungakanani kolo hambo kugcinwa njengamandla anokusetyenziswa. Ezi zinto zimbini zabelana ngenyathelo eliphakathi, igradiyenti yeeproton enqumla kwinwebu yangaphakathi ye-mitochondrion, kwaye nantoni na etshintsha indlela le gradiyenti edityaniswe ngokuqinileyo ngayo nokwenziwa kwe-ATP inokwenza ezi ziphumo zimbini zitshintshe ziye kumacala ahlukeneyo. I-methylene blue iluncedo ekucaciseni oku kuba ibonwe isenza zombini: inyusa ukusetyenziswa kweoksijini kunye ne-ATP kwezinye iisampulu, ize inyuse ukusetyenziswa kweoksijini ngoxa i-ATP ingatshintshi okanye isihla kwezinye.

Abafundi abafuna ukuqala ngomfanekiso obanzi wokudluliselwa kwee-elektroni banokuqala ngendlela i-methylene blue ethutha ngayo ii-elektroni kwikhonkco lokuphefumla, baze abafundi abafuna isigama seemvavanyo zokuqala zeoksijini bafunde oko imilinganiselo yokuqala yokuphefumla yakubonisa ngokwenene.

Ukuphefumla kweseli, i-ATP, negradiyenti ephakathi kwazo

Ii-elektroni ezivela kwi-NADH nakwi-FADH2 zingena kwikhonkco kwiikhompleksi I no-II, zidlule kwikhompleksi III ukuya kwi-cytochrome c, zize zidlule kwikhompleksi IV ukuya kwioksijini. Amandla akhululwa kwiikhompleksi I, III, no-IV ampompa iiproton ziphume kwimatriksi ziye kwisithuba esiphakathi kweenwebu. Oko kwahlulwa kweentlawulo zombane nobumuncu kudala amandla aqhuba iiproton, yaye inxalenye yawo yombane, umahluko wombane kwinwebu, idla ngokuba yeyona ibalaseleyo.

I-ATP synthase ivumela iiproton ukuba zibuyele kwimatriksi kwaye isebenzisa amandla akhululwayo ukudibanisa i-ADP nefosfeyithi zenze i-ATP. Ngoko ikhonkco lihamba ngolu hlobo:

ukusetyenziswa kweoksijini, kulandele ukumpontshwa kweeproton, kulandele igradiyenti, kuze kulandele ukwenziwa kwe-ATP.

Ingxaki kukuba iiproton zinokubuya ngezinye iindlela. Nakuphi na ukubuya okungadluli kwi-ATP synthase kukuvuza kweeproton. Ukuvuza kunyanzela ikhonkco ukuba liphinde limpompe kwaezo proton ukugcina umahluko wombane kwinwebu uzinzile, nto leyo esebenzisa ioksijini engakumbi ngaphandle kokwenza i-ATP engakumbi. Ukuvuza okunamandla ngokwaneleyo kukuqhawuka kokudityaniswa: ukusetyenziswa kweoksijini kuyenyuka ngoxa i-ATP ingatshintshi okanye isihla, yaye amandla achithakeleyo aphuma njengobushushu.

Imeko 3, imeko 4, nomlinganiselo wolawulo lokuphefumla

Isigama sakudala sale nkqubo sivela kwiimitochondria ezikhutshiweyo kwiiseli. Imeko 3 kukuphefumla xa kukho isubstrate kunye ne-ADP: i-ATP synthase inciphisa igradiyenti, umahluko wombane kwinwebu uyehla, ikhonkco liyakhawuleza ukuze liwubuyisele, yaye ukusetyenziswa kweoksijini kuphezulu kuba kwenziwa i-ATP. Imeko 4 kukuphefumla emva kokuba iphelile i-ADP: i-ATP synthase ayisebenzi, igradiyenti iyenyuka, umahluko wombane ophezulu kwinwebu uchasa ukumpontshwa okungakumbi, yaye ukusetyenziswa kweoksijini kwehla kuye kwinqanaba elifunekayo ukuhlawulela ukuvuza.

Ngoko umlinganiselo wolawulo lokuphefumla, oyimeko 3 eyahlulwe ngemeko 4, ubonisa indlela iinkqubo zesampulu ezidityaniswe ngokuqinileyo ngayo. Umlinganiselo ophezulu uthetha ukuba i-ADP ilawula ukuphefumla ngamandla. Umlinganiselo owehlayo xa imeko 4 inyuka uthetha ukuba ukuvuza kuya kulawula ngakumbi. Le yindlela enceda ekuqondeni iziphumo ze-methylene blue ezingezantsi.

Kukho umfanekiso omnye wengqondo ofanele ukhunjulwe. Umahluko wombane ophezulu kwinwebu ucothisa ikhonkco. Ukuphelisa loo mahluko kulikhawulezisa. Ikhonkco lisabela kubunzima bokumpompa, hayi ngokuthe ngqo ekubeni i-ATP iyenziwa na.

Xa iziphumo zitshintsha kunye

Owona mzekelo ucacileyo wokudityaniswa uvela kwiimitochondria ezikhutshwe kwingqondo yeehagu zaseGuinea ezineekhompleksi zokuphefumla ezivaliweyo. Kwi-100 nanomolar ukuya kwi-1 micromolar ye-methylene blue, ukusetyenziswa kweoksijini xa ziphumle kwenyuka xa kusetyenziswa i-glutamate kunye ne-malate, i-succinate, okanye i-glycerophosphate njengesibaso, ngoxa ukuphefumla okuvuselelwa yi-ADP kwakungatshintshi. Kwiimitochondria ezonakaliswe yityhefu kwikhompleksi I okanye kwikhompleksi III, le dayi yandisa kancinane ukuveliswa kwe-ATP, yabuyisela umahluko wombane kwinwebu, yaza yaphucula ukufunxwa kwekhalsiyam. Indlela ecetywayo yindlela enqumlayo: idayi yamkela ii-elektroni phambi kwendawo evaliweyo ize izidlulisele kwi-cytochrome c, idlule ecaleni kwekhompleksi eyonakeleyo.

Umzekelo wesibini wokudityaniswa usebenzisa umthombo we-ATP owahluke ngokupheleleyo. Kwiimitochondria ezikhutshwe kwingqondo apho i-ATP synthase yayithintelwe, i-methylene blue yayisakuvuselela ukuphefumla kuyo yonke isubstrate eyavavanywayo. Kodwa ukwenziwa kwe-ATP kwenyuka kuphela kwi-alpha ketoglutarate nakwi-glutamate, iisubstrate ezimbini ezenza i-succinyl CoA. Xa i-oligomycin ivala i-ATP synthase, i-ATP eyongezelelekileyo yavela ekongezweni kweqela lefosfeyithi kwinqanaba lesubstrate okwenziwa yi-succinyl CoA ligase kumjikelo we-citric acid, hayi ekongezweni kweqela lefosfeyithi okuqhutywa yi-oxidation. Idayi yaphinda yabuyisela umahluko wombane kwinwebu xa ikhompleksi I ne-ATP synthase zazithintelwe kunye. Apha ukusetyenziswa kweoksijini ne-ATP zatshintsha kunye, kodwa kuphela apho isubstrate yayivumela indlela yesibini yokwenza i-ATP. Kwi-succinate okanye kwi-malate, ukuphefumla kwenyuka ngaphandle kwe-ATP eyongezelelekileyo. Idayi enye, igumbi elinye, isibaso esahlukileyo, impendulo eyahlukileyo.

Xa iziphumo zahlukana

Imizekelo yokwahlukana nayo ipapashiwe kwaye ifundisa ngokulinganayo. Kuphononongo luka-1997 lweemitochondria ezikhutshwe kwisibindi seempuku, i-methylene blue yakhawulezisa ukuphefumla kwemeko 4 kwiimitochondria ezidityaniswe ngokuqinileyo ezaziphefumla zisebenzisa i-succinate, nto leyo eyehlisa umlinganiselo wolawulo lokuphefumla. Isiphumo sasibonakala ukususela kwi-0.5 micromolar kwaye sasinamandla kwi-5 micromolar, uxinaniso olusondele kumanqanaba akwiplasma emva kokufakwa kwe-100 milligram emthanjeni ngexesha elinye. Kwi-5 micromolar iimitochondria nazo zadumba, nangona isiphene sokudityaniswa sabonakala kuqala kuxinaniso olusezantsi, nto leyo exhasa ukuba ukuvuza kwandulela umonakalo wesakhiwo kunokuba kubangelwe ngulo monakalo. Kwiimitochondria ezazingasadityaniswanga, idayi yavuselela ukuphefumla ngendlela exhomekeke kuxinaniso enokufikelela kwinqanaba lokuhlutha. Ukusetyenziswa kweoksijini kwenyuka kuzo zombini iisampulu. Ukwenziwa kwe-ATP ngokweyunithi yeoksijini esetyenzisiweyo akuzange kwenyuke. Lo ngumzekelo ocacileyo wokuqhawuka kokudityaniswa kunye nokuthuthwa kwee-elektroni, kwimolekyuli enye.

Owona mahluko uphawulekayo uvela kwiretina. Kwiimpuku ezingenayo i-AIF ngokwaneleyo nakwiiseli ezamkela ukukhanya eziphathwe nge-rotenone, i-methylene blue yagcina ubukhulu beretina, iziphawuli zeeseli ezamkela ukukhanya, kunye nesakhiwo seemitochondria, yaza yehlisa umlinganiselo we-NADH kwi-NAD kwaye yathomalalisa iindlela zokusabela kuxinzelelo kuquka ukusabela kwiiproteni ezingasongekanga kunye nokususwa kweemitochondria nge-mitophagy. Yakwenza oko ngaphandle kokulungisa ukunqongophala kwe-ATP. Ukukhuselwa ngaphandle kokubuyiselwa kwamandla kuthetha ukuba inzuzo yavela ekulinganisweni kwe-redox nasekugcinweni kwemeko yeemitochondria, hayi kwi-ATP eyongezelelekileyo. Nabani na olinganisa ukusinda kwethishu nokubuyiselwa kokuveliswa kwamandla uya kuyitolika ngokupheleleyo ngendlela engachanekanga loo mvavanyo.

Uphando lweemitochondria zengqondo longeza icala leendleko kulo mfanekiso. Kwaezo nxinaniso zisezantsi ezaphucula iinkqubo zamandla ebhayoloji zandisa nokuveliswa kwe-hydrogen peroxide phantsi kwazo zonke iimeko ezavavanywayo, zaza zacothisa ukususwa kwayo. Oku kwalinganiswa ngovavanyo lwe-Amplex olulungelelanisiweyo kunokuba kusetyenziswe idayi engajolisanga kwinto ethile. I-ATP engakumbi nento engakumbi ebangela i-oxidation zeza kunye.

Uluhlu lwemibuzo yokukhokela ukufunda

Imibuzo emine yahlula isiphumo esidityanisiweyo kwesingadityaniswanga.

Okokuqala, sesiphi isiphumo esalinganiswa ngokwenene. Ukusetyenziswa kweoksijini kuphela akunakubonisa i-ATP. Ukwenziwa kwe-ATP, umahluko wombane kwinwebu, nomlinganiselo wolawulo lokuphefumla nganye yongeza inxalenye engabonwa yi-electrode yeoksijini. Isikhokelo sokufunda amabango ophando lwe-methylene blue sichaza ngokweenkcukacha olu qwalaselo lweziphumo ezilinganisiweyo.

Okwesibini, yeyiphi isubstrate eyasetyenziswa sisibaso ziimitochondria. Isiphumo se-succinyl CoA sibonisa ukuba ukhetho lwesibaso lunokugqiba ukuba ukuphefumla okongezelelekileyo kungakwazi na ukuvelisa i-ATP eyongezelelekileyo kwaphela.

Okwesithathu, loluphi uxinaniso olwasetyenziswa. I-methylene blue ukusuka kwi-nanomolar ukuya kwi-micromolar ephantsi kwiimitochondria zengqondo yazisa ukuphucuka okuncinane kwiinkqubo zamandla ebhayoloji, kodwa kunye neendleko zokwanda kwezinto ezibangela i-oxidation; isiqingatha se-micromolar nangaphezulu kwiimitochondria zesibindi kwanciphisa ukudityaniswa; i-5 micromolar yongeza ukudumba. Uxinaniso luyinxalenye yendlela yokusebenza, hayi inkcukacha engasemva nje.

Okwesine, yeyiphi imodeli eyavelisa isiphumo. Iimitochondria ezikhutshiweyo kwiiseli zityhila uqhagamshelwano lwenkqubo, kodwa iiseli neethishu ezipheleleyo zongeza uthutho, ukuncitshiswa kwe-methylene blue ukuya kuhlobo olungenambala, kunye nezinye iindawo ezikhuphisana ngokwamkela ii-elektroni. Umsebenzi waselebhu wokumisela izixa, kuquka indlela uxinaniso nenkqubo yovavanyo ezichaphazela ngayo iziphumo ze-methylene blue, udibanisa amanani egumbi lovavanyo nawo nawaphi na amabango ngomntu.

Ukusetyenziswa kweoksijini kubonisa ukuhamba kwee-elektroni. I-ATP ibonisa ukuba kungakanani kolo hambo kugcinwe njengamandla. I-methylene blue inokutshintsha nokuba yeyiphi kwezi zimbini, kwaye iimvavanyo ezingentla zibonisa zonke iindibaniselwano ezine ezilandelayo: zombini ziyenyuka, ukuphefumla kunyuka kuphela apho isubstrate ivumela khona, ukuphefumla kuyenyuka ngoxa ukudityaniswa kuncipha, kwaye ithishu iyagcinwa ngoxa i-ATP ingatshintshi. Inani eliboniswa yi-electrode yeoksijini sisiqalo sokutolika, hayi isiphelo sako.