SIANOKOBALAMINA (HUAWITAMINA B12)
Āhua me ngā Āhuatanga
He paura karaihe whero, he paura karaihe rānei tēnei hua, kāore he kakara, kāore he reka, ā, he kaha te whakapūmau i te makuku. He paku wairewa ki te wai, ki te etanoru rānei, kāore e wairewa ki te chloroform, ki te ether rānei. He ātete ki te wera, engari kāore e whai hua ina pāngia e ngā matū whakahāweawe, whakaiti rānei (pēnei i te huaora C, te hauwai waikura rānei, me ētahi atu), ngā tote konganuku taumaha me ngā waikawa kaha me ngā kawakore kaha.
Hanganga Matū
He matū rite tonu te Huaora B12 kei roto ngā iona cobalt. Ko tōna hanganga pokapū he mowhiti corrin papatahi e hangaia ana e ngā pyrrole e whā e hono ana. E toru ngā wāhanga o ngā ngota o te Huaora B12: he mowhiti gourin e whakakīia ana e ngā ngota N e whā me ngā iona cobalt pokapū; 5,6-dimethylbenzimidazole (5,6-dimethylbenzimidazole, DMBI) e hono ana ki ngā ngota N-7 me ngā iona cobalt hei ngota huaora B 12 o ngā ligands taumata-iti (α). Hei tāpiri, e hono ana hoki te DMBI ki te aminopropanol mā roto i ngā rōpū phosphate, ā, e hono ana te aminopropanol ki te mekameka taha waikawa propionic i runga i te pyrrole D; rōpū adenosyl, rōpū methyl rānei. E hono ana ki ngā iona cobalt hei hanga i te ligand o runga (β) o ngā ngota huaora B12. Ka hangaia ngā momo matū huaora B12 rerekē ina rerekē te rōpū o te pukapuka matū mai i te pukapuka matū o runga i te tuaka o te mowhiti goline. Ka honoa te rōpū hydroxyl (-OH) ki te ion cobalt i roto i te mowhiti gluline hei hanga i te hydroxycobalamin. Waihoki, ka honoa te deoxyadenosine (5'-deoxyadenosyl), te methyl (-CH3), te cyanide (-CN) me ngā ion cobalt hei hanga i te adenosine cobalt. Ko te amine (deoxyadenosylcobalamin), te methylcobalamin (methylcobalamin) me te cyanocobalamin (cyanocobalamin). I roto i te taiao, ko te ahua whakamutunga o te huaora B12 i hangaia e ngā moroiti ko te adenosine cobalamine (coenzyme B12), te methyl cobalamine me te hydroxycobalamine. Heoi, nā te mea kāore i te tino pumau ō rātou āhuatanga, ka tāpirihia te konutai cyanide i roto i te tukanga purenga ahumahi hei huri i te ahua tūturu o te huaora B12 ki te cyanocobalamin pumau ake.
Te Mahi ā-tinana
Whakapai ake i te tere whakamahinga o te waikawa folic, te hanga meththionine (i hangaia mai i te cysteineine nui) me te choline me te waikawa folic, me te hanga i ngā matū cyanocobalamin pēnei i te methyl coballamin me te coenzyme B12 i roto i te tukanga whakaputa prine me te pyrimidine, me te whai wāhi ki te tukanga methylation o te maha o ngā matū nui. Ina ngoikore te huaora B12, ka whakaitihia te mahi o te whakawhiti i ngā rōpū methyl mai i te waikawa methyl tetrahydrofolic, ka kore e taea te whakamahi i te waikawa folic, ka arahi ki te ngoikore o te waikawa folic. Kia mau tonu te pākia me te mahi o te pukupuku myelin io. Ka taea e te kore o te huaora B12 te whakararu i ngā mate neurological, te pirau o te tuaiwi, me te mate matū ka taea te whakararu i ngā tohu hinengaro kino. Ka taea e te kore o te huaora B12 te arahi ki te neuritis peripheral. Ko ngā whakaaturanga wawe o te ngoikore o te huaora B12 i roto i ngā tamariki ko te kare ā-roto rerekē, te puhoi o te whakaaturanga, te puhoi o te tauhohenga, ā, i te mutunga ka arahi ki te anemia. Whakatairanga i te whanaketanga me te pakeketanga o ngā toto toto whero. Ka hurihia te Methylpropandiyl coenzyme A hei succinoyl coenzyme A, ā, ka whai wāhi atu ki te huringa waikawa tricarboxylic, e hono ana te succinyl coenzyme A ki te hanga heme. Ka whai wāhi atu hoki te Huaora B12 ki te hanga o te waikawa deoxynucleic (DNA), te pākia o te ngako, te warowaihā me te pūmua, ā, ka whakanui ake i te hanga o ngā waikawa karihi me ngā pūmua.
