Feem ntau ntawm cov enzymes rau kev siv cov kev ua catalytic xav tau cov ntsiab lus pabcuam - cofactors. Cov tshuaj no tsis yog-protein nyob rau hauv qhov xwm txheej thiab tsis yog ib feem ntawm cov enzyme molecule. Lub luag haujlwm ua haujlwm ntawm cov protein thiab cofactor yog hu ua holoenzyme, thiab tsuas yog ib feem ntawm cov protein hu ua apoenzyme. Ib cofactor uas yog ib feem ntawm ib qho enzyme mus tas li thiab txuas rau nws los ntawm covalent daim ntawv cog lus yog hu ua pab pawg prosthetic.
Hauv kev nkag siab dav dua, cofactor yog ib pab pawg ntxiv hauv cov protein ntau uas tswj hwm nws hauv lub xeev ua haujlwm. Hauv enzyme proteins, cofactors tuaj yeem koom ncaj qha rau hauv cov tshuaj tiv thaiv catalysis.
yam ntxwv thiab hom cofactors
Cofactors yog cov khoom hnyav molecular uas tau muab faib ua 2 pawg loj:
- ions ntawm divalent hlau (zinc, magnesium,poov tshuaj, tooj liab, manganese, hlau, thiab lwm yam);
- coenzymes - organic non-protein compounds.
Nyob rau hauv lem, coenzymes muab faib mus rau hauv cov vitamins nrog lawv cov derivatives thiab cov tebchaw ntawm non-vitamin xwm. Cov tom kawg suav nrog:
- UDP-glucose;
- nucleotides;
- metalloporphyrins;
- FAD, OVER+, NADP+;
- glutathione;
- ubiquinone;
- YS-adenosylmethionine.
Cofactors tuaj yeem tsim ob qho tib si muaj zog covalent thiab tsis muaj zog nrog cov enzymes. Qee pab pawg cuam tshuam nrog polypeptide feem ntau heev uas nws nyuaj rau cais lawv txawm tias tshuaj.
nyuaj hauv kev txhais cov ntsiab lus ntawm "cofactor" thiab "coenzyme"
Hauv kev nkag siab nqaim, cofactors yog hlau ions, thiab coenzymes yog pawg ntawm cov organic. Yog tias peb xav txog cov ntsiab lus no los ntawm qhov pom ntawm lawv qhov tseem ceeb, ces cov cofactor tsis koom nrog cov tshuaj tiv thaiv catalysis, thiab yog li ntawd tsis yog coenzyme. Hauv kev txhais lus dav dav, coenzyme yog qhov tshwj xeeb ntawm cofactor.
Cov lus txhais li no yog vim qhov tseeb tias hauv biochemistry niaj hnub no cov ntsiab lus yog cov ntsiab lus tsis meej uas tsis muaj lub ntsiab lus dav dav.
Lub luag haujlwm lom neeg ntawm cofactors
Enzyme cofactors tuaj yeem ua tau ntau yam haujlwm, suav nrog:
- kev koom tes hauv kev tsim thiab ruaj khov ntawm tertiary thiab quaternary conformations;
- ruaj khov ntawm substrate lossis catalytic chaw, kom ntseeg taucomplementarity ntawm lawv;
- kev koom tes hauv catalysis ua ib qho ntxiv substrate;
- kev tswj hwm kev ua haujlwm enzymatic;
- kev koom tes hauv cov tshuaj tiv thaiv redox.
Txawm hais tias lub tshuab ua haujlwm thiab cov tshuaj lom neeg ntawm cofactor, thaum nws tsis tuaj, enzyme tsis tuaj yeem ua haujlwm catalytic. Txawm li cas los xij, muaj ib pawg me me ntawm cov enzymes uas nws ua haujlwm tsis cuam tshuam nrog cofactors.
