CYANOCOBALAMIN (VITAMINI B12)
Mawonekedwe ndi Katundu
Chogulitsachi ndi ufa wa kristalo wofiira kapena kristalo, wopanda fungo, wopanda kukoma ndipo uli ndi mphamvu zoyambitsa chinyezi. Chimasungunuka pang'ono m'madzi kapena ethanol, sichisungunuka mu chloroform kapena ether. Chimalimbana ndi kutentha, koma sichigwira ntchito chikagwiritsidwa ntchito ndi zinthu zowononga kapena zochepetsa (monga vitamini C kapena hydrogen peroxide, ndi zina zotero), mchere wolemera wachitsulo ndi ma acid amphamvu ndi alkali amphamvu.
Kapangidwe ka Mankhwala
Vitamini B12 ndi gulu la equioctaphedral lomwe lili ndi ma ayoni a cobalt. Kapangidwe kake kapakati ndi mphete yathyathyathya ya corrin yopangidwa ndi ma pyrroles anayi olumikizidwa. Mamolekyu a vitamini B12 amapangidwa pafupifupi magawo atatu: mphete ya gourin yolumikizidwa ndi ma atomu anayi a N ndi ma ayoni a cobalt apakati; 5,6-dimethylbenzimidazole (5,6-dimethylbenzimidazole, DMBI) yolumikizidwa ku ma atomu a N-7 ndi ma ayoni a cobalt monga ma molekyulu a vitamini B 12 a ma ligands otsika (α). Kuphatikiza apo, DMBI imalumikizidwanso ndi aminopropanol kudzera m'magulu a phosphate, ndipo aminopropanol imalumikizidwa pamodzi ndi unyolo wa propionic acid pa pyrrole D; gulu la adenosyl kapena gulu la methyl. Imalumikizidwa ndi ma ayoni a cobalt kuti apange ligand yapamwamba (β) ya ma molekyulu a vitamini B12. Mitundu yosiyanasiyana ya zinthu za vitamini B12 zimapangidwa pamene gulu la buku la mankhwala limasiyana ndi buku la mankhwala lapamwamba pa mzere wa mphete ya goline. Gulu la hydroxyl (-OH) limalumikizidwa ndi ayoni ya cobalt mu mphete ya gluline kuti ipange hydroxycobalamin. Mofananamo, deoxyadenosine (5'-deoxyadenosyl), methyl (-CH3), cyanide (-CN) ndi ayoni a cobalt zimalumikizidwa kuti zipange adenosine cobalt motsatana. Amine (deoxyadenosylcobalamin), methylcobalamin (methylcobalamin) ndi cyanocobalamin (cyanocobalamin). Mwachilengedwe, mawonekedwe omaliza a vitamini B12 omwe amapangidwa ndi tizilombo ndi adenosine cobalamine (coenzyme B12), methyl cobalamine ndi hydroxycobalamine. Komabe, chifukwa cha makhalidwe awo osakhazikika kwambiri, sodium cyanide imawonjezedwa mwaluso mu njira yoyeretsera mafakitale kuti isinthe mawonekedwe achilengedwe a vitamini B12 kukhala cyanocobalamin yokhazikika kwambiri.
Ntchito Yachilengedwe
Sinthani kuchuluka kwa kugwiritsa ntchito folic acid, kupanga meththionine (yopangidwa kuchokera ku cysteineine yambiri) ndi choline ndi folic acid, ndi kupanga cyanocobalamin precursors monga methyl coballamin ndi coenzyme B12 popanga prine ndi pyrimidine, ndikutenga nawo mbali mu njira ya methylation ya mankhwala ambiri ofunikira. Pamene vitamini B12 ilibe, ntchito yosamutsa magulu a methyl kuchokera ku methyl tetrahydrofolic acid imachepa, zomwe zimapangitsa kuti folic acid ikhale yosagwiritsidwa ntchito, zomwe zimapangitsa kuti folic acid isakhale yokwanira. Sungani kagayidwe kachakudya ndi ntchito ya mitsempha ya myelin. Kusowa kwa vitamini B12 kungayambitse matenda amitsempha, kuwonongeka kwa msana, komanso mankhwala osokoneza bongo kungayambitse zizindikiro zazikulu zamaganizo. Kusowa kwa vitamini B12 kungayambitse matenda a mitsempha ya m'magazi. Zizindikiro zoyambirira za kusowa kwa vitamini B12 mwa ana ndi kusakhazikika maganizo, kufooka, kuchitapo kanthu pang'onopang'ono, ndipo pamapeto pake zimayambitsa kuchepa kwa magazi m'thupi. Kulimbikitsa kukula ndi kukhwima kwa maselo ofiira amagazi. Methylpropandiyl coenzyme A imasinthidwa kukhala succinoyl coenzyme A ndipo imatenga nawo mbali mu tricarboxylic acid cycle, momwe succinyl coenzyme A imagwirizanirana ndi kapangidwe ka heme. Vitamini B12 imatenga nawo mbali mu kapangidwe ka deoxynucleic acid (DNA), kagayidwe ka mafuta, chakudya ndi mapuloteni, komanso imawonjezera kapangidwe ka nucleic acid ndi mapuloteni.
