Ubururu bwa metilene na mitokondiriya: itwarwa rya elekitironi n'ibimenyetso

Tekereza ku ngero ebyiri zateguwe zishyizwe iruhande rumwe. Zombi zirimo mitokondiriya zo mu bwonko zahungabanyijwe na rotenone, ikinyabutabire gifunga Urusobe I rw'urukurikirane rw'ubuhumekero. Mu rugero rumwe, ukora igerageza ashyiramo ingano y'ubururu bwa metilene ipimwe muri micromolar akoresheje pipeti. Imikoreshereze ya ogisijeni iragaruka igice. Itandukaniro rya potansiyeli y'amashanyarazi hagati y'impande z'agahu na ryo riragaruka igice. Ikorwa rya ATP rirasubukurwa ku rugero ruto. Mu gatoki k'igerageza kari iruhande, icyuma gipima perogiside kigaragaza ikindi gice cy'ibibaye: ikorwa rya perogiside ya hidirojeni ryikubye inshuro nyinshi, kuri buri ngano yageragejwe, no kuri buri sibusitirate yakoreshejwe.

Ibyo bipimo byombi ni byo. Ubururu bwa metilene ni umutwazi wa elekitironi ushobora gutuma zikomeza gutembera zinyuze iruhande rw'igice cyangiritse cy'urukurikirane rw'ubuhumekero, ariko uwo mutwazi anatera ikiguzi cyo kwiyongera kwa perogiside mu gihe abikora. Iyo uzirikanye ibyo bintu byombi icyarimwe, inyandiko z'ubushakashatsi ku mikorere y'ubururu bwa metilene muri mitokondiriya zirumvikana. Iyo uzirikanye kimwe gusa, zisa n'izivuga igitangaza cyangwa akaga, bitewe n'inyandiko wabanje gusoma.

Umutwazi wa elekitironi, mu magambo yoroshye

Urukurikirane rw'ubuhumekero ni nk'umurongo w'abahererekanya ibintu. Elekitironi zinjirira ku Rusobe I (zivuye kuri NADH) cyangwa ku Rusobe II no ku misemburo ya flavin ifitanye isano na rwo (zivuye kuri succinate n'ibindi bizitanga bisa na yo), zikanyura ku Rusobe III zikagera ku mutwazi ugenda witwa cytochrome c, hanyuma zikanyura ku Rusobe IV zikagera kuri ogisijeni. Buri hererekanya rituma porotoni zisunikwa zikambuka agahu k'imbere, kandi ubusumbane buturutse kuri ibyo bugatuma hakorwa ATP. Iyo ufunze ahantu hamwe muri uwo murongo, ibice biwubanziriza birahagarara.

Ubururu bwa metilene bwiyongeramo nk'umutwazi ukorera ku wundi murongo. Imiterere yabwo yatakaje elekitironi izakira zivuye ku batwazi bo mu bice bibanza, bugahinduka imiterere yungutse elekitironi itagira ibara, ari yo leucomethylene blue. Iyo miterere ihererekanya izo elekitironi mu bice bikurikiraho maze igasubira kuba ubururu. Iyo miterere yombi isobanurwa mu nyandiko ku miterere ibiri ihindurana binyuze mu gutanga no kwakira elekitironi, naho imyitwarire rusange y'iryo hererekanya ikaboneka mu bisobanuro by'uburyo rusange bukora. Ikibazo kitarakemuka ni aho uwo mutwazi yongera kwinjirira muri uwo murongo: ahafatirwa quinol ku Rusobe III, hazwi nk'ahantu Qo, cyangwa kuri cytochrome c ako kanya. Inzira yiganje iterwa n'imiterere y'igerageza, nk'uko isesengura ryo kunyura iruhande rw'Urusobe III ribisobanura mu buryo burambuye.

Icyo ubushakashatsi butatu ku mbeba n'inyamaswa zijya gusa na zo bwapimye koko

Ubushakashatsi uko ari butatu bwakoresheje mitokondiriya zo mu bwonko zatandukanyijwe n'uturemangingo, ni ukuvuga utugingo ngengamikorere twakuwe mu turemangingo tugashyirwa mu gisukika gifite ibigize bizwi kandi gifasha gukomeza pH. Nta turemangingo twuzuye, nta nyamaswa zahawe irangi, nta bantu bakoreweho ubushakashatsi. Ubwinshi buvugwa ni ubw'irangi mu gisukika gikikije utwo tugingo ngengamikorere, si ingano umuntu afata anyuze mu kanwa. Iyo uzirikanye iyo mipaka, imibare irasobanuka.

Ubushakashatsi bwa mbere, bwakorewe kuri mitokondiriya zatandukanyijwe n'uturemangingo two mu bwonko bw'ingurube zo muri Gineya, hakoreshejwe 100 nanomolar kugeza kuri 2 micromolar, bwagaragaje akamaro n'ikiguzi mu rugero rumwe rwateguwe. Muri mitokondiriya nzima, irangi ryongereye imikoreshereze ya ogisijeni mu gihe cyo kuruhuka, ariko ntiryahinduye ubuhumekero bwongerewe na ADP; bityo ikorwa rya ATP rifitanye isano n'ubwo buhumekero ntiryiyongereye. Igihe Urusobe I rwari rwafunzwe, 2 micromolar yagaruye ikorwa rya ATP iva kuri 46 ikagera kuri 93 nanomoles ku munota kuri milligram, ugereranyije n'igipimo gisanzwe cyegereye 1109. Igihe Urusobe III rwari rwafunzwe, iyo ngano yagaruye ATP iva hafi ya 46 ikagera kuri 63, ugereranyije n'igipimo gisanzwe cyegereye 910. Itandukaniro rya potansiyeli y'amashanyarazi no kwinjiza kalisiyumu byagarutse igice. Gufunga Urusobe IV hakoreshejwe cyanide ntibyashoboye kurengwa, bikerekana ko aho elekitironi zisohokera zikagira akamaro hari mbere y'Urusobe IV rukora. Buri garuka ry'imikorere ryari rifite agaciro mu mibare y'ibarurishamibare ariko ari rito: ijanisha ry'ikorwa rya ATP risanzwe ryari munsi ya cumi.

Ubushakashatsi bwa kabiri, bwakorewe kuri mitokondiriya zo mu gice cy'inyuma cy'ubwonko bw'imbeba nto hakoreshejwe hafi 1 micromolar, bwemeje ko bishoboka kunyura iruhande rw'Urusobe I, ariko bugaragaza umupaka ku Rusobe III. Rotenone yagabanyije ubuhumekero buva hafi ya 121 bugera munsi ya 2 nanomoles za ogisijeni ku munota kuri milligram, maze irangi rirabwongera bugera hafi ya 21, ni ukuvuga hafi kimwe cya gatandatu cy'igipimo gisanzwe, mu gihe itandukaniro rya potansiyeli y'amashanyarazi ry'agahu ryagarutse hafi ryose. Ariko Urusobe III rumaze gufungwa, haba ubuhumekero cyangwa iryo tandukaniro rya potansiyeli, nta na kimwe cyagarutse hagati ya 1 na 5 micromolar, kandi iryo fungwa ryagabanyije ikimenyetso cya perogiside yaterwaga n'irangi. Abanditsi batanze igitekerezo ko irangi ryungutse elekitironi rizitangira ku hantu Qo h'Urusobe III: iyo aho hantu hafashwe, umutwazi nta ho aba agifite ho kuzitanga.

Ubushakashatsi bwa gatatu, bwakorewe kuri mitokondiriya zo mu bwonko bw'imbeba nto, imbeba nini n'ingurube zo muri Gineya, ahanini hakoreshejwe 2 micromolar, bwagerageje mu buryo butaziguye icyo ubushakashatsi bwabanje butavugagaho rumwe, busanga ko ifungwa ry'Urusobe III rishobora kurengwa. Igihe myxothiazol, ifunga ahantu Qo, yagabanyaga ubuhumekero bw'ibanze ku kigero cya 88 ku ijana, irangi ryagaruye imikoreshereze ya ogisijeni igera hafi ya 62 ku ijana by'igipimo cyo mu gihe urusobe rutafunzwe. Mu igerageza ritaziguye, kimwe cya kabiri cya micromolar cyatumye cytochrome c yaturutse hanze yakira elekitironi nubwo Urusobe III rwari rwafunzwe, bishyigikira inzira iva kuri NADH ikanyura mu irangi ikagera kuri cytochrome c hanyuma ku Rusobe IV. Ariko ubuhumekero bwagaruwe bwitwaye mu buryo budasanzwe: ADP yongewemo yagabanyije imikoreshereze ya ogisijeni aho kuyongera, kandi gufunga ikorwa rya ATP byongereye ubuhumekero. Itandukaniro rya potansiyeli y'amashanyarazi ryagarutse igice gusa. Imikoreshereze myinshi ya ogisijeni iherekejwe n'ihuzwa ry'ubuhumekero n'ikorwa rya ATP ryahindutse ntabwo ari ikorwa ry'ingufu risanzwe.

Impamvu laboratwari zitavuga rumwe, n'icyo kibisobanura

Ibisobanuro bishingiye ku bwoko bw'inyamaswa ni byo bibanza kuvuguruzwa. Itsinda rya gatatu ryasubiyemo ubushakashatsi mu bwoko butatu bw'imbeba n'inyamaswa zijya gusa na zo, ribona ko kunyura iruhande rw'urusobe byagaragaye mu buryo bumwe muri zose, harimo n'umuryango w'imbeba nto wari waratangajweho ko ibyo bitabonekamo. Ahubwo ibitandukanye ni ubwinshi bw'irangi (1 ugereranyije na 2 micromolar), ingano z'ibifunga urusobe, ibisukika bikomeza pH, uburyo bwo gutandukanya mitokondiriya n'uturemangingo, cyane cyane uko imiterere y'ikorwa ry'ingufu yagereranyijwe: kunyura iruhande rw'urusobe bigaragara neza mbere yo kongeramo ADP, ari na ho igisubizo cya ADP kinyuranye n'icyari cyitezwe kigaragara. Igishushanyo kitagoreka ukuri rero kigaragaza inzira ebyiri zo gusohokera zishingiye ku miterere y'igerageza, imwe ku hantu Qo n'indi kuri cytochrome c. Umutwazi atanga elekitironi aho imiterere y'ubutabire y'aho hantu ibimwemerera.

Ikiguzi cya perogiside

Ibimenyetso by'ikiguzi birahamye nk'iby'igaruka ry'imikorere. Mu bushakashatsi ku ngurube zo muri Gineya, irangi ryongereye irekurwa rya perogiside muri buri miterere yageragejwe: mu kuruhuka, mu gukora ATP no mu gihe imikorere yahungabanyijwe n'ibinyabutabire, hakoreshejwe sibusitirate uko ari eshatu. Mu gihe cy'ikorwa rya ATP, ikorwa rya perogiside ryavuye hafi ya 148 rirenga 1500 picomoles ku munota kuri milligram kuri 1 micromolar, ndetse na 100 nanomolar yatumye ikimenyetso kirenga inshuro enye icyo cyari cyo. Irangi ryanagabanyije umuvuduko wo gukuraho perogiside hafi inshuro 2.6, bityo ikimenyetso kigaragaza ko ikorwa ryihuta kandi ikurwaho rigatinda. Uburyo bw'ubutabire bwatanzweho igitekerezo ni uko irangi ryungutse elekitironi riziha ogisijeni mu buryo butaziguye, nta superoxide ishobora gutahurwa ibonetse; ariko ibyo biracyari ibisobanuro bishoboka, si intambwe yemejwe.

Ubushakashatsi ku mbeba nto bwongeramo ikintu gituma ibisobanuro birushaho kuba ingirakamaro, nubwo birushaho kugorana. Perogiside yazamutse cyane uko ingano y'irangi yiyongeraga, iva ku gipimo cy'ibanze cyegereye 76 igera hafi ya 2000 picomoles ku munota kuri milligram kuri 2 micromolar, nyamara gufunga Urusobe III byagabanyije igice cyaterwaga n'irangi. Iyo perogiside iza guturuka gusa ku mwitikio hagati y'irangi ryungutse elekitironi na ogisijeni, gufunga urukurikirane ntibyari kugira ingaruka zingana gutyo. Ariko birazigira, bityo urukurikirane na rwo rugira uruhare. Isuzuma ry'ubushobozi bwo kurwanya no guteza iyangirika rituruka ku kwamburwa elekitironi rishyira iyi myitwarire ibiri mu rwego rwagutse, naho isesengura rya ogisijeni ugereranyije na ATP risobanura impamvu imibare ya ogisijeni yonyine idashobora kwemeza ibivugwa ku ngufu.

Kugarura imikorere si ugusana

Imvugo ikwiye kureka gukoreshwa ni "ese ubururu bwa metilene busana mitokondiriya." Gusana byasobanura gukosora kurambye: inzobe zongera kubakwa, ihuzwa ry'ubuhumekero n'ikorwa rya ATP rikomeza na nyuma y'uko umuti uvuyeho, imikorere igaruka mu turemangingo twuzuye, hanyuma imikorere y'ikinyabuzima kizima ikarushaho kuba myiza. Nta na rumwe muri izo nyandiko eshatu rubyerekana. Zigaragaza guhindura inzira mu gihe gito mu tugingo ngengamikorere tumaze gutandukanywa n'uturemangingo, mu gihe hari ifungwa ryatewe n'ibinyabutabire mu buryo bw'igerageza, ikorwa rya ATP rikaba ari agace gato k'irisanzwe kandi rimwe na rimwe ihuzwa ryaryo n'ubuhumekero rikaba ridasanzwe rwose. Rotenone na antimycin ni ibikoresho bya laboratwari, si ingero zigereranya gusaza cyangwa indwara za mitokondiriya mu bantu. Nta kintu hano gisobanura ko umuntu muzima yagira ingufu nyinshi kurushaho; icyo ni ikibazo cyihariye cy'ibimenyetso gifite inyandiko zacyo z'ubushakashatsi ku bantu.

Imipaka itatu ituma umwanzuro uwo ari wo wose ku kwigeragerezaho ugamije guhindura imikorere y'umubiri utagoreka ukuri. Ubwa mbere, ubwinshi mu gisukika si ingano ifatwa: 0.1 kugeza kuri 2 micromolar mu gisukika gikikije utugingo ngengamikorere twatandukanyijwe n'uturemangingo ntacyo bivuga ku ngano umuntu yanywa kugira ngo habeho ubwo bwinshi bw'irangi ritaboshywe kuri mitokondiriyoni yo mu bwonko bwe, cyane ko irangi ryirundanya cyangwa rikarekurwa bitewe n'itandukaniro rya potansiyeli y'amashanyarazi ry'agahu ubwaryo. Ubwa kabiri, ogisijeni si ingufu: irangi rishobora kongera imikoreshereze ya ogisijeni binyuze mu kwizunguruka no mu kumeneka kwa elekitironi, kimwe no mu iyongerwaho rya fosifate ritanga ATP. Bityo gupima ubuhumekero utapimye ATP n'itandukaniro rya potansiyeli y'amashanyarazi ntibyemerera umuntu kuvuga ko ingufu ziyongereye. Ubwa gatatu, akamaro n'ikiguzi bigomba kuvugirwa hamwe: imvugo iyo ari yo yose ku igaruka rya potansiyeli cyangwa ATP itavuga ukwiyongera kwa perogiside kwabiherekeje iba itanga amakuru agoretse ku igerageza. Izindi ngingo zigomba kwitabwaho zirimo iringaniza rya NAD mu gutanga no kwakira elekitironi, imiterere y'igisubizo uko ingano ihinduka n'amabwiriza yo guhitamo ibipimo by'igerageza.

Akandi kantu kamwe ko kuzirikana mu bikorwa: ubushobozi bwo gutwara elekitironi ni umwihariko w'iyo molekile nyirizina. Molekile zifitanye isano na yo zavanyweho amatsinda ya metil, nka Azure B, na zo zitanga kandi zikakira elekitironi, ariko zikitwara ukundi. Bityo igisukika cyatangiye kwangirika gitanga igerageza ritandukanye n'iry'irangi ritarangiritse. Iyo ni imwe mu mpamvu zo gusaba ko ibisabwa byose by'igitabo ngenderwaho cy'ubuziranenge bw'imiti byubahirizwa kandi hakabaho inyandiko yatangajwe yerekeye icyiciro cy'ibicuruzwa, aho gushingira gusa ku isuzuma ry'ibyuma birimo. Ubutabire buterwa n'urumuri bwongeraho indi ngingo yo kwitondera mu mikoreshereze irimo kumurika, ivugwa mu gukomatanya n'urumuri rutukura.

Umwanzuro ufite imbibi ukomeza kwemezwa n'ibi byose kandi ukwiriye kugumaho: ubururu bwa metilene bushobora gukora nk'umutwazi wa elekitironi mu miterere runaka muri mitokondiriya zangiritse zatandukanyijwe n'uturemangingo, bugakomeza igice cy'itembera ryazo ariko bukishyurwa ukwiyongera kwa perogiside. Ibirenze ibyo byose, yaba ingufu, kuramba cyangwa gusana, biracyategereje ibimenyetso ubu bushakashatsi butari bugenewe gutanga.