CYANOCOBALAMIN (VITHAMINI B12)
Sebopeho le Matlotlo
Sehlahisoa sena ke phofo e khubelu ea kristale kapa kristale, ha e na monko, ha e na tatso 'me e na le thepa e matla e bakang mongobo. E qhibiliha hanyane ka metsing kapa ethanol, ha e qhibilihe ka har'a chloroform kapa ether. E hanela mocheso, empa e ka se sebetse ha e pepesehetse lintho tse oxidating kapa tse fokotsang (tse kang vithamine C kapa hydrogen peroxide, jj.), letsoai la tšepe e boima le li-acid tse matla le alkali tse matla.
Sebopeho sa Lik'hemik'hale
Vithamine B12 ke motsoako oa equioctaphedral o nang le li-ion tsa cobalt. Sebopeho sa eona se bohareng ke lesale le bataletseng la corrin le entsoeng ka li-pyrrole tse 'ne tse hokahaneng. Limolek'hule tsa vithamine B12 li entsoe ka likarolo tse 3: lesale la gourin le chylated ke liathomo tse 'ne tsa N le li-ion tsa cobalt tse bohareng; 5,6-dimethylbenzimidazole (5,6-dimethylbenzimidazole, DMBI) tse hokahaneng le liathomo tsa N-7 le li-ion tsa cobalt e le limolek'hule tsa vithamine B 12 tsa li-ligand tse tlase (α). Ho phaella moo, DMBI e boetse e hokahane le aminopropanol ka lihlopha tsa phosphate, 'me aminopropanol e hokahane ka kopanelo le ketane ea lehlakore la propionic acid ho pyrrole D; sehlopha sa adenosyl kapa sehlopha sa methyl. E hokahane le li-ion tsa cobalt ho theha ligand e kaholimo (β) ea limolek'hule tsa vithamine B12. Mefuta e fapaneng ea lintho tsa vithamine B12 e thehoa ha sehlopha sa buka ea lik'hemik'hale se fapane le buka ea lik'hemik'hale e kaholimo ho axis ea lesale la goline. Sehlopha sa hydroxyl (-OH) se hokahantsoe le ion ea cobalt ka har'a lesale la gluline ho etsa hydroxycobalamin. Ka mokhoa o ts'oanang, li-ion tsa deoxyadenosine (5'-deoxyadenosyl), methyl (-CH3), cyanide (-CN) le cobalt li hokahantsoe ho hlahisa adenosine cobalt ka ho latellana. Amine (deoxyadenosylcobalamin), methylcobalamin (methylcobalamin) le cyanocobalamin (cyanocobalamin). Ka tlhaho, mofuta oa ho qetela oa vithamine B12 e entsoeng ke likokoana-hloko ke adenosine cobalamine (coenzyme B12), methyl cobalamine le hydroxycobalamine. Leha ho le joalo, hobane thepa ea tsona ha e tsitsitse haholo, sodium cyanide e eketsoa ka maiketsetso ts'ebetsong ea tlhoekiso ea indasteri ho fetola mofuta oa tlhaho oa vithamine B12 hore e be cyanocobalamin e tsitsitseng haholoanyane.
Mosebetsi oa 'mele
Ntlafatsa sekhahla sa tshebediso ya folic acid, ho kopanya meththionine (e entsweng ho tswa ho cysteineine e ngata) le choline ka folic acid, le ho kopanya cyanocobalamin precursors jwalo ka methyl coballamin le coenzyme B12 tshebetsong ya ho hlahisa prine le pyrimidine, mme o kenye letsoho tshebetsong ya methylation ya metsoako e mengata ya bohlokwa. Ha vithamine B12 e haella, mosebetsi wa ho fetisetsa dihlopha tsa methyl ho tswa ho methyl tetrahydrofolic acid o a fokotseha, e leng se etsang hore folic acid e be sebopeho se sa sebedisweng, se lebisang ho khaello ya folic acid. Boloka metabolism le tshebetso ya sheath ya myelin ya methapo. Ho hloka vithamine B12 ho ka baka mathata a methapo ya kutlo, ho senyeha ha lesapo la mokokotlo, mme buka ya dikhemikhale e ka baka matshwao a tebileng a kelello. Ho hloka vithamine B12 ho ka lebisa ho neuritis ya peripheral. Dipontsho tsa pele tsa ho hloka vithamine B12 ho bana ke maikutlo a sa tlwaelehang, ho hlahisa maikutlo ka botswa, ho arabela butle, mme qetellong ho lebisa ho anemia. Kgothaletsa ntshetsopele le kgolo ya disele tse kgubedu tsa madi. Methylpropandiyl coenzyme A e fetoloa hore e be succinoyl coenzyme A mme e nka karolo potolohong ya tricarboxylic acid, moo succinyl coenzyme A e amanang le ho qaptjoa ha heme. Vithamine B12 e boetse e nka karolo ho qaptjweng ha deoxynucleic acid (DNA), metabolism ya mafura, dikhabohaedreite le protheine, mme e eketsa ho qaptjwa ha nucleic acid le diprotheine.
