Umjikelezo weKrebs - izigaba eziphambili kunye nokubaluleka kwenkqubo yezinto eziphilayo

Ubuninzi bemveliso yamakhemikhali yekhabhoni ikhutshwa phantsi kweemeko ze-aerobic kunye nokuthatha inxaxheba kwe-oxygen. Umjikelezo weKrebs ubizwa ngokuba ngumjikelezo we-citric acid, okanye ukuphefumula kwamaselula. Inzululwazi ezininzi zathatha inxaxheba ekuchazeni ukuphendulwa komntu kule nkqubo: A. Szent-Gyorgyi, A. Lenringer, H. Krebs, ogama lakhe lingumjikelezo, SE Severin nabanye.

Kukho ukulungelelaniswa okufutshane phakathi kwe-anaerobic kunye ne-aerobic digestion ye-carbohydrate. Okokuqala, ibonakaliswa phambi kwe-asiriya ye-pyruvic, ephelisa ukutyalwa kwe-carbohydrate ye-anaerobic kwaye iqala ukuphefumula kweselula (i-Krebs cycle). Zombini izigaba zithathwa yi-enzyme ezifanayo. Amandla ekhemikhali akhululwa ngexesha le-phosphorylation, igcinwe ngendlela ye-macroergs ye-ATP. Kwiimpendulo zamakhemikhali, ii-coenzymes ezifanayo (i-NAD, i-NADP) kunye nezicwangciso zithatha inxaxheba. Ukwahlukana kunjengale ndlela: ukuba ukugaya i-anaerobic ye-carbohydrates kubonakala kakhulu kwindawo ye-hyaloplasm, iimpendulo zokuphefumula kwamaselula zenzeka ngokuyinhloko kwimitochondria.

Ngaphantsi kweemeko ezithile, ukuchasana kubonakala phakathi kwezigaba zombini. Ngaloo ndlela, phambi koo-oxygen, izinga lokusabela kwe- glycolysis liyehla kakhulu (umphumo wePasteur). Imveliso ye-glycolysis inokuvimbela i-aerobic metabolism ye-carbohydrate (i-Crabtree effect).

Umjikelezo weKrebs unemizekelo yeempendulo zamakhemikhali, ngenxa yoko imveliso ye-carbohydrates digestion ifakwe kwi-carbon dioxide kunye namanzi, kwaye amandla eekhemikhali aqokelelwa kwiimveliso ezininzi. Ngexesha lokuphefumula kweselula, "umphathiswa" - oxaloacetic acid (SHCHO) yenziwa. Emva koko, ukuxhaswa kwenzeka kunye "nomthwali" we-actic acetic acid residu. Kukho i-tricarboxylic acid-lemon. Kwixesha leempendulo zamakhemikhali, kukho "inzuzo" yentsalela ye-acetic acid kumjikelezo. Izilwanyana ezilishumi elinesibhozo ze-adenosine triphosphate zenziwa kwi-molecule nganye ye- asiriya ye- pyruvic . Ekupheleni komjikelo, "umthumeli" ukhutshwayo ophendulayo kunye nama-molecule omtsha asele asethi ase-acidtic asele.

Umjikelezo weKrebs: ukuphendula

Ukuba umkhiqizo wokuphela we-anaerobic digestion ye-carbohydrates yi-lactic acid, kwaye phantsi kwefuthe le dectate dehydrogenase i-oxidized to acid pyruvic acid. Icandelo le-molecule ye-asidi ye-pyruvic iya kwi-synthesis "ye-carrier" ye-SHCH phantsi kwefuthe le-enzyme ye-pyruvate carboxylase kwaye phambi kwe-i-Mg2 + ions. Ingxenye yamakhemleksi e-asiriya ye-pyruvic iyimvelaphi yokubunjwa "kwe-acetate esebenzayo" - i-acetylcoenzyme A (i-acetyl-CoA). Impendulo ithathwa phantsi kwefuthe le-pyruvate dehydrogenase. I-Acetyl-CoA iqulethe ubudlelwane obukhulu, apho i-5-7% yamandla iqokelelwa. Ubuninzi bemveliso yamakhemikhali lwakhiwa ngenxa ye-oxidation ye "acetate esebenzayo".

Ngaphantsi kwefuthe le-citrate synthetase, umjikelo weKrebs uqala ukusebenza, okhokelela ekwakheni i-citrate acid. Le asidi phantsi kweempembelelo ze-aconitate hydratase i-dehydrogeni kwaye iguqulwe kwi-acid ye-cis-aconitic, elandelayo emva kokuba ukongezwa kwimilekyuli yamanzi iya kuba i-isomonic acid. Phakathi kwee-matatu ze-tricarboxylic acid, i-equilibrium enamandla isungulwe.

I-isolimonic acid i-oxidized i-oxalyl succinic acid, ene-decarboxylated kwaye iguqulelwe kwi-alpha-ketoglutaric acid. Ukuphendula kuthathwa yi-enzyme isocitrate dehydrogenase. I-Alpha-ketoglutaric acid i-decarboxylated phantsi kwempembelelo ye-enzyme 2-oxo- (alpha-keto) -glutarate dehydrogenase, ekhokelela ekubunjweni kwe-succinyl-CoA equkethe ukudibanisa okuninzi.

Kwinqanaba elilandelayo, i-succinyl-CoA phantsi kwezenzo ze-enzyme succinyl-CoA synthetase idlulisela ubuhlobo obuphezulu be-GDF (i-guanosine diphosphate acid). I-GTP (i-guanosine triphosphate acid) phantsi kwefuthe le-enzyme ye-GTP-adenylate kinase inikeza uxhumano olunzulu lwe-AMP (adenosine monophosphate acid). Umjikelezo weKrebs: iifomula - GTP + AMP - GDF + ADP.

I-asidi ye-succinic phantsi kwesenzo se-enzyme succinate dehydrogenase (i-SDG) i-oxidized to fumaric acid . I-coenzyme ye-LDH yi-flavin adenine dinucleotide. I-Fumarate, phantsi kwefuthe le-enzyme fumarate hydratase, iguqulwa ibe yi-malic acid, yona leyo idibeneyo ukwenza i-SHCHO. Ekubeni kwe-acetyl-CoA kwinkqubo yokusabela, i-SCOQ iphinda ifakwe kwi-tricarboxylic acid cycle.

Ngaloo ndlela, i-molecule ye-ATP isuka kuma-38 AT molecule (ezimbini nge-anaerobic glycolysis, ezithandathu nge-oxidation ezimbini ze-NADH + H + ezenziwe ngexesha le-glycolytic oxidoreduction, kunye ne-30 yi-CTC). I-coefficient of efficiency ye-CTC yi-0.5. Amandla asele apheliswa ngendlela yobushushu. I-CTC ikhidiza i-acid ye-lactate engu-16-33%, ubukhulu bayo buya kwi-resynthesis ye-glycogen.