Shin ƙarin amfani da oxygen yana nufin ƙarin ATP? Darussa daga nazarin methylene blue

An saka mitochondrion da aka ware a wani ɗakin gwaji mai tushen makamashi amma babu ADP. Yana amfani da oxygen a hankali. Idan aka ƙara ADP, amfani da oxygen yana ƙaruwa sau da yawa. Idan aka jira har ADP ya ƙare, amfani da oxygen yana raguwa ya koma yadda yake. Tushen makamashin bai sauya ba. Bukatar ATP ce kawai ta sauya.

Wannan ɗan jerin abubuwa ya ƙunshi dukkan bambancin da wannan labarin yake bayani a kai. Amfani da oxygen yana auna saurin da elektron suke gudana ta sarkar numfashin salula zuwa oxygen. Samar da ATP kuwa yana auna yawan wannan gudu da ake kamawa a matsayin makamashi mai amfani. Biyun suna da wani mataki na haɗin gwiwa a tsakiya: bambancin tarin proton a ɓangarorin membrane na cikin mitochondria. Duk wani abu da ya sauya ƙarfin haɗin wannan bambanci da samar da ATP zai iya sa sakamakon biyun ya nufi hanyoyi daban-daban. Methylene blue yana taimakawa wajen fahimtar wannan domin an ga yana yin duka biyun: yana ƙara amfani da oxygen tare da ATP a wasu shirye-shiryen gwaji, kuma yana ƙara amfani da oxygen yayin da ATP bai sauya ba ko yake raguwa a wasu.

Masu karatu da suke son fara da cikakken bayanin tsarin miƙa elektron za su iya farawa da yadda methylene blue yake jigilar elektron ta sarkar numfashin salula. Waɗanda suke son fahimtar kalmomin da aka yi amfani da su a gwaje-gwajen oxygen na farko kuma za su iya karanta abin da ma'aunin numfashin salula na farko ya nuna a zahiri.

Numfashin salula, ATP, da bambancin tarin proton da ke tsakaninsu

Elektron daga NADH da FADH2 suna shiga sarkar a rukunai I da II, su bi ta rukuni III zuwa cytochrome c, sannan ta rukuni IV zuwa oxygen. Makamashin da ake saki a rukunai I, III, da IV yana tura proton daga matrix zuwa sararin da ke tsakanin membranes. Wannan rarrabuwar cajin lantarki da matakin acidity ita ce ƙarfin tura proton. Ɓangarenta na lantarki, wato bambancin ƙarfin lantarki a membrane, yawanci shi ne ya fi rinjaye.

ATP synthase yana barin proton su koma cikin matrix, sannan yana amfani da makamashin da aka saki wajen haɗa ADP da phosphate su zama ATP. Don haka tsarin shi ne:

amfani da oxygen, sai tura proton, sai bambancin tarinsu, sannan samar da ATP.

Sai dai proton na iya komawa ta wasu hanyoyi. Duk komawar da ta kauce wa ATP synthase ita ce zubewar proton. Wannan zubewa tana tilasta sarkar ta sake tura waɗannan proton domin ta riƙe bambancin ƙarfin lantarki a membrane ba tare da sauyi ba. Hakan yana amfani da ƙarin oxygen ba tare da samar da ƙarin ATP ba. Idan zubewar ta yi ƙarfi sosai, tana katse haɗin aiki: amfani da oxygen yana ƙaruwa yayin da ATP bai sauya ba ko yake raguwa, kuma makamashin da aka rasa yana fita a matsayin zafi.

Yanayi 3, yanayi 4, da rabon sarrafa numfashin salula

Asalin kalmomin da aka saba amfani da su wajen wannan bayani ya fito ne daga nazarin mitochondria da aka ware. Yanayi 3 shi ne numfashin salula lokacin da sinadarin da ake sarrafawa da ADP suke nan: ATP synthase yana rage bambancin tarin proton, bambancin ƙarfin lantarki a membrane yana raguwa, sarkar tana ƙara sauri domin ta sake gina shi, kuma amfani da oxygen yana da yawa domin ana samar da ATP. Yanayi 4 shi ne numfashin salula bayan ADP ya ƙare: ATP synthase yana zaman banza, bambancin tarin proton yana ƙaruwa, babban bambancin ƙarfin lantarki a membrane yana hana ƙarin tura proton, kuma amfani da oxygen yana raguwa zuwa adadin da ake buƙata domin rama zubewar proton.

Saboda haka, rabon sarrafa numfashin salula, wato yanayi 3 da aka raba da yanayi 4, yana nuna ƙarfin haɗin aiki a mitochondria da aka shirya don gwaji. Babban rabo yana nufin ADP yana sarrafa numfashin salula sosai. Rabo mai raguwa tare da ƙaruwa a yanayi 4 yana nufin zubewar proton tana fara rinjaye. Wannan ita ce hanyar fahimtar sakamakon methylene blue da ke ƙasa.

Akwai wani tsarin tunani da ya kamata a riƙe. Babban bambancin ƙarfin lantarki a membrane yana rage saurin sarkar. Rage wannan bambanci yana ƙara mata sauri. Sarkar tana amsawa ne ga yadda tura proton ya zama da wahala, ba kai tsaye ga ko ana samar da ATP ba.

Lokacin da sakamakon biyun suke tafiya tare

Misali mafi bayyana na haɗin aiki ya fito daga mitochondria da aka ware daga ƙwaƙwalwar aladun Guinea waɗanda aka toshe rukunansu na numfashin salula. A tarin methylene blue daga 100 nanomolar zuwa 1 micromolar, amfani da oxygen a lokacin hutawa ya ƙaru lokacin da aka yi amfani da glutamate tare da malate, succinate, ko glycerophosphate a matsayin tushen makamashi, amma numfashin salula da ADP ya motsa bai sauya ba. A mitochondria da aka hana rukuni I ko rukuni III aiki da guba, rinin ya ƙara samar da ATP kaɗan, ya dawo da bambancin ƙarfin lantarki a membrane, kuma ya inganta shigar calcium. Hanyar da aka ba da shawarar ita ce taƙaitacciyar hanya: rinin yana karɓar elektron kafin wurin da aka toshe, sannan ya miƙa su ga cytochrome c, yana kauce wa rukunin da ya lalace.

Misali na biyu na haɗin aiki yana amfani da wani tushen ATP daban gaba ɗaya. A mitochondria da aka ware daga ƙwaƙwalwa waɗanda aka hana ATP synthase aiki, methylene blue har yanzu ya ƙara numfashin salula a kan kowane sinadarin da aka gwada a matsayin tushen makamashi. Amma samar da ATP ya ƙaru ne kawai a kan alpha ketoglutarate da glutamate, sinadarai biyun da suke samar da succinyl CoA. Yayin da oligomycin ya toshe ATP synthase, ƙarin ATP ya fito ne daga ƙara phosphate a matakin sinadarin da ake sarrafawa ta hanyar succinyl CoA ligase a zagayowar citric acid, ba daga ƙara phosphate ta hanyar oxidation ba. Rinin kuma ya dawo da bambancin ƙarfin lantarki a membrane lokacin da aka hana rukuni I da ATP synthase aiki tare. A nan, amfani da oxygen da ATP sun ƙaru tare, amma sai inda sinadarin tushen makamashi ya ba da damar amfani da hanya ta biyu ta samar da ATP. A kan succinate ko malate, numfashin salula ya ƙaru ba tare da ƙarin ATP ba. Rini iri ɗaya, ɗakin gwaji ɗaya, tushen makamashi daban, sakamako daban.

Lokacin da sakamakon biyun suke rabuwa

An wallafa misalan rabuwa kamar misalan haɗin aiki, kuma su ma suna koyarwa sosai. A wani nazarin mitochondria da aka ware daga hantar beraye a 1997, methylene blue ya ƙara saurin numfashin salula na yanayi 4 a mitochondria masu haɗin aiki mai ƙarfi waɗanda suke amfani da succinate. Wannan ya rage rabon sarrafa numfashin salula. An ga tasirin tun daga 0.5 micromolar, kuma ya yi ƙarfi a 5 micromolar, tarin da yake kusa da matakan da ake samu a plasma bayan allurar 100 milligram da aka yi a jijiya lokaci guda. A 5 micromolar, mitochondria sun kuma kumbura. Amma matsalar haɗin aiki ta fara bayyana a ƙananan matakan tarin sinadarin, abin da yake nuna cewa zubewar proton ta fara kafin lalacewar tsarin, maimakon lalacewar ce ta jawo ta. A mitochondria waɗanda aka katse haɗin aikinsu, rinin ya motsa numfashin salula ta hanyar da ta dogara da tarin sinadarin kuma take kaiwa iyakar ƙaruwa. Amfani da oxygen ya ƙaru a duka shirye-shiryen gwajin. Samar da ATP ga kowane adadin oxygen da aka yi amfani da shi bai ƙaru ba. Wannan shi ne misalin katse haɗin aiki tare da jigilar elektron da ake samu a littattafan koyarwa, duka a cikin ƙwayar sinadari ɗaya.

Rabuwa mafi ɗaukar hankali ta fito daga retina. A ɓeraye masu ƙarancin AIF da salula masu karɓar haske da aka yi wa rotenone, methylene blue ya kiyaye kaurin retina, alamomin salula masu karɓar haske, da tsarin mitochondria. Ya kuma rage rabon NADH da NAD, ya lafa hanyoyin amsa ga damuwa, ciki har da amsar ga furotin da bai naɗe yadda ya kamata ba da mitophagy. Ya yi haka ba tare da gyara ƙarancin ATP ba. Kariya ba tare da dawo da makamashi ba tana nufin amfanin ya biyo ta daidaiton redox da kiyaye cikakken tsarin mitochondria, ba ta ƙarin ATP ba. Duk wanda ya ɗauka cewa tsirar nama yana nufin an dawo da samar da makamashi zai yi kuskuren fahimtar wannan gwajin gaba ɗaya.

Aikin nazarin mitochondria na ƙwaƙwalwa ya ƙara wani ɓangaren hasara ga wannan lissafi. Waɗannan ƙananan matakan tarin sinadarin da suka inganta samarwa da amfani da makamashi sun kuma ƙara samar da hydrogen peroxide a kowane yanayin da aka gwada, sannan suka rage saurin kawar da shi. An auna wannan da gwajin Amplex da aka daidaita, maimakon rini wanda ba ya keɓance abin da ake aunawa. Ƙarin ATP da ƙarin sinadarin da ke haifar da oxidation sun zo tare.

Jerin abubuwan dubawa yayin karatu

Tambayoyi huɗu suna bambanta sakamakon da haɗin aiki ya kasance daga wanda aka katse haɗin aiki.

Na farko, wane ma'aunin sakamako ne aka auna a zahiri? Amfani da oxygen shi kaɗai ba zai iya nuna ATP ba. Samar da ATP, bambancin ƙarfin lantarki a membrane, da rabon sarrafa numfashin salula kowannensu yana ƙara wani bayani da na'urar auna oxygen ba za ta iya gani ba. Jagorar karanta iƙirarin bincike kan methylene blue tana bayyana wannan tsari na lura da ma'aunin sakamako dalla-dalla.

Na biyu, wane sinadari ne aka bai wa mitochondria a matsayin tushen makamashi? Sakamakon succinyl CoA ya nuna cewa zaɓin tushen makamashi na iya tantance ko ƙarin numfashin salula zai iya zama ƙarin ATP ko kaɗan.

Na uku, wane matakin tarin sinadarin aka yi amfani da shi? Methylene blue daga nanomolar zuwa ƙananan matakan micromolar a mitochondria na ƙwaƙwalwa ya ba da ɗan ingantawa wajen samarwa da amfani da makamashi, tare da ƙarin sinadaran da ke haifar da oxidation; rabin micromolar da sama da haka a mitochondria na hanta ya raunana haɗin aiki; 5 micromolar ya ƙara kumburi. Tarin sinadarin yana cikin tsarin yadda yake aiki, ba ƙaramin bayanin gefe ba.

Na huɗu, a wane tsarin gwaji aka samu sakamakon? Mitochondria da aka ware suna bayyana tsarin haɗin aikin, amma salula da nama cikakku suna ƙara abubuwa kamar jigilar sinadarin, sauya shi zuwa siga marar launi ta karɓar elektron, da wasu wuraren karɓar elektron masu gogayya. Aikin nazarin adadin sinadarin da ake amfani da shi a dakin gwaje-gwaje, ciki har da yadda tarin sinadarin da tsarin gwaji suke tsara tasirin methylene blue, shi ne gada tsakanin lambobin ɗakin gwaji da duk wani iƙirari game da mutum.

Amfani da oxygen yana nuna gudun elektron. ATP yana nuna yawan wannan gudu da aka kama a matsayin makamashi. Methylene blue na iya sauya ko ɗaya daga cikinsu, kuma gwaje-gwajen da ke sama sun nuna duk sakamako huɗu da suka biyo baya: biyun suna ƙaruwa, numfashin salula yana ƙaruwa ne kawai inda sinadarin tushen makamashi ya ba da dama, numfashin salula yana ƙaruwa yayin da haɗin aiki yake raguwa, kuma ana kiyaye nama yayin da ATP bai sauya ba. Lambar da na'urar auna oxygen ta nuna ita ce farkon fassarar sakamako, ba ƙarshenta ba.