Lo lus "enzyme" muaj cov hauv paus hauv Latin. Hauv kev txhais lus, nws txhais tau tias "sourdough". Hauv lus Askiv, lub tswv yim "enzyme" yog siv, muab los ntawm Greek lo lus, txhais tau tias tib yam. Enzymes yog cov protein tshwj xeeb. Lawv tau tsim nyob rau hauv cov hlwb thiab muaj peev xwm ua kom ceev cov txheej txheem biochemical. Hauv lwm lo lus, lawv ua raws li cov khoom siv roj ntsha. Cia peb xav ntxiv seb qhov twg yog qhov tshwj xeeb ntawm kev ua ntawm enzymes. Cov hom tshwj xeeb kuj yuav piav qhia hauv kab lus.
yam ntxwv dav dav
Qhov tshwm sim ntawm kev ua haujlwm catalytic ntawm qee cov enzymes yog vim muaj ntau cov tshuaj tsis muaj protein ntau. Lawv hu ua cofactors. Lawv muab faib ua 2 pawg: hlau ions thiab ib tug xov tooj ntawm inorganic tshuaj, nrog rau cov coenzymes (organic compounds).
Txoj Haujlwm Mechanism
Los ntawm lawv cov tshuaj lom neeg, cov enzymes koom nrog pawg ntawm cov proteins. Txawm li cas los xij, tsis zoo li yav tas los, cov ntsiab lus nyob rau hauv kev txiav txim siab muaj qhov chaw nquag. Nws yog ib qho tshwj xeeb ntawm kev ua haujlwm ntawm cov amino acid residues. Lawv nruj me ntsis rau hauv qhov chaw vim yog lub tertiary lossis quaternary qauv ntawm cov enzyme. Nyob rau hauv nquagqhov chaw yog cais catalytic thiab substrate chaw. Cov tom kawg yog qhov txiav txim siab qhov tshwj xeeb ntawm cov enzymes. Lub substrate yog cov khoom uas cov protein ua. Yav dhau los, nws tau ntseeg tias lawv cov kev sib cuam tshuam yog ua raws li lub hauv paus ntsiab lus ntawm "tus yuam sij rau lub tsev fuabtais." Hauv lwm lo lus, qhov chaw nquag yuav tsum kom meej meej sib haum rau lub substrate. Tam sim no, ib qho kev xav sib txawv yeej muaj. Nws ntseeg tau tias tsis muaj cov ntawv sau qhia tseeb, tab sis nws tshwm sim nyob rau hauv chav kawm ntawm kev sib cuam tshuam ntawm cov tshuaj. Qhov thib ob - catalytic - qhov chaw cuam tshuam rau qhov tshwj xeeb ntawm qhov kev txiav txim. Hauv lwm lo lus, nws txiav txim siab qhov xwm txheej ntawm cov tshuaj tiv thaiv nrawm.
Kev tsim kho
Txhua cov enzymes tau muab faib ua ib- thiab ob-cov khoom. Cov qub muaj cov qauv zoo ib yam li cov qauv ntawm cov proteins yooj yim. Lawv tsuas muaj cov amino acids xwb. Pab pawg thib ob - cov protein - suav nrog cov protein thiab cov khoom tsis muaj protein. Qhov kawg yog coenzyme, thawj yog apoenzyme. Cov tom kawg txiav txim siab lub substrate tshwj xeeb ntawm cov enzyme. Ntawd yog, nws ua haujlwm ntawm qhov chaw substrate hauv qhov chaw ua haujlwm. Lub coenzyme, raws li, ua raws li thaj tsam catalytic. Nws muaj feem xyuam rau qhov tshwj xeeb ntawm qhov kev txiav txim. Vitamins, hlau, thiab lwm yam uas tsis muaj molecular hnyav tebchaw yuav ua raws li coenzymes.
Catalysis
Qhov tshwm sim ntawm cov tshuaj tiv thaiv tshuaj yog cuam tshuam nrog kev sib tsoo ntawm cov molecules ntawm cov tshuaj sib cuam tshuam. Lawv cov lus tsa suab hauv qhov system yog txiav txim siab los ntawm qhov muaj peev xwm dawb zog. Rau cov tshuaj tiv thaiv tshuaj, nws yog ib qho tsim nyog kom cov molecules hloov pauvmob. Hauv lwm lo lus, lawv yuav tsum muaj lub zog txaus kom dhau los ntawm lub zog thaiv. Nws sawv cev rau qhov tsawg kawg nkaus ntawm lub zog los ua kom tag nrho cov molecules reactive. Tag nrho cov catalysts, nrog rau cov enzymes, muaj peev xwm txo tau lub zog barrier. Qhov no ua rau muaj kev nrawm nrawm ntawm cov tshuaj tiv thaiv.
Dab tsi yog qhov tshwj xeeb ntawm enzymes?
Lub peev xwm no tau nthuav tawm hauv kev nrawm ntawm tsuas yog qee yam tshuaj tiv thaiv. Enzymes tuaj yeem ua rau tib lub substrate. Txawm li cas los xij, txhua tus ntawm lawv yuav nrawm tsuas yog cov tshuaj tiv thaiv tshwj xeeb xwb. Lub reactive tshwj xeeb ntawm cov enzyme tuaj yeem taug qab los ntawm cov piv txwv ntawm pyruvate dehydrogenase complex. Nws suav nrog cov protein uas cuam tshuam rau PVK. Cov tseem ceeb yog: pyruvate dehydrogenase, pyruvate decarboxylase, acetyltransferase. Cov tshuaj tiv thaiv nws tus kheej yog hu ua oxidative decarboxylation ntawm PVC. Nws cov khoom yog active acetic acid.
Kev faib tawm
Muaj cov hom enzyme hauv qab no:
- Stereochemical. Nws yog qhia nyob rau hauv lub peev xwm ntawm ib yam khoom los cuam tshuam ib qho ntawm cov ua tau substrate stereoisomers. Piv txwv li, fumarate hydrotase tuaj yeem ua rau fumarate. Txawm li cas los xij, nws tsis cuam tshuam rau cis isomer - maleic acid.
- Txhob. Qhov tshwj xeeb ntawm enzymes ntawm hom no yog qhia nyob rau hauv lub peev xwm ntawm ib yam khoom los cuam tshuam tsuas yog ib qho substrate. Piv txwv li, sucrase reacts nkaus xwb nrog sucrose, arginase nrog arginine, thiab lwm yam.
- Txiv neej. Qhov tshwj xeeb ntawm cov enzymes hauv qhov norooj plaub yog qhia nyob rau hauv lub peev xwm ntawm ib yam khoom los cuam tshuam ib pab pawg ntawm substrates uas muaj ib daim ntawv cog lus ntawm tib hom. Piv txwv li, alpha-amylase reacts nrog glycogen thiab starch. Lawv muaj glycosidic hom ntawv cog lus. Trypsin, pepsin, chymotrypsin cuam tshuam ntau cov proteins ntawm pawg peptide.
Kub
Enzymes muaj qhov tshwj xeeb hauv qee yam mob. Rau feem ntau ntawm lawv, qhov kub ntawm + 35 … + 45 degrees yog qhov zoo tshaj plaws. Thaum ib yam khoom raug muab tso rau hauv cov xwm txheej nrog qis qis, nws cov haujlwm yuav txo qis. Lub xeev no hu ua reversible inactivation. Thaum qhov kub thiab txias, nws lub peev xwm yuav rov qab los. Nws yog tsim nyog hais tias thaum muab tso rau hauv tej yam kev mob uas t yog siab tshaj qhov qhia qhov tseem ceeb, inactivation kuj yuav tshwm sim. Txawm li cas los xij, nyob rau hauv cov ntaub ntawv no, nws yuav irreversible, vim hais tias nws yuav tsis rov qab los thaum kub poob. Qhov no yog vim lub denaturation ntawm lub molecule.
Kev cuam tshuam ntawm pH
Tus nqi ntawm cov molecule nyob ntawm acidity. Yog li, pH cuam tshuam rau kev ua haujlwm ntawm qhov chaw nquag thiab qhov tshwj xeeb ntawm enzyme. Qhov zoo tshaj plaws acidity Performance index rau txhua yam yog txawv. Txawm li cas los xij, feem ntau nws yog 4-7. Piv txwv li, rau qaub ncaug alpha-amylase, qhov zoo acidity yog 6.8. Lub caij no, muaj ntau qhov kev zam. Qhov zoo tshaj acidity ntawm pepsin, piv txwv li, yog 1.5-2.0, chymotrypsin thiab trypsin yog 8-9.
Kev sib tw
Qhov muaj enzyme ntau dua, qhov tshuaj tiv thaiv sai dua. Zoo sib xwsKev txiav txim siab kuj tuaj yeem ua tiav txog qhov concentration ntawm substrate. Txawm li cas los xij, cov ntsiab lus saturating ntawm lub hom phiaj yog kev txiav txim siab rau txhua yam khoom. Nrog nws, tag nrho cov chaw ua haujlwm yuav raug nyob los ntawm cov substrate muaj. Hauv qhov no, qhov tshwj xeeb ntawm cov enzyme yuav yog qhov siab tshaj plaws, tsis hais qhov ntxiv tom ntej ntawm lub hom phiaj.
Regulatory Substances
Lawv tuaj yeem muab faib ua inhibitors thiab activators. Ob leeg ntawm cov pawg no tau muab faib ua cov tsis tshwj xeeb thiab tshwj xeeb. Cov tshuaj activators tom kawg suav nrog cov kua tsib ntsev (rau lipase hauv pancreas), chloride ions (rau alpha-amylase), hydrochloric acid (rau pepsin). Nonspecific activators yog magnesium ions uas cuam tshuam rau kinases thiab phosphatase, thiab cov inhibitors tshwj xeeb yog cov peptides ntawm proenzymes. Cov tom kawg yog cov ntaub ntawv tsis muaj zog ntawm cov khoom. Lawv tau qhib thaum cleavage ntawm lub davhlau ya nyob twg peptides. Lawv hom tshwj xeeb sib raug rau txhua tus neeg proenzyme. Piv txwv li, nyob rau hauv ib tug inactive daim ntawv, trypsin yog tsim nyob rau hauv daim ntawv ntawm trypsinogen. Nws lub chaw ua haujlwm raug kaw los ntawm lub davhlau ya nyob twg hexapeptide, uas yog ib qho tshwj xeeb inhibitor. Nyob rau hauv tus txheej txheem ntawm kev ua kom, nws yog cais tawm. Qhov chaw nquag ntawm trypsin qhib vim qhov tshwm sim. Nonspecific inhibitors yog ntsev los ntawm cov hlau hnyav. Piv txwv li, tooj liab sulfate. Lawv provoke lub denaturation ntawm compounds.
Kev txwv tsis pub
Nws tuaj yeem sib tw. Qhov no tshwm sim yog qhia nyob rau hauv cov tsos ntawm cov qauv zoo sib xws ntawm tus inhibitor thiab lub substrate. Lawv yognkag mus rau hauv kev tawm tsam rau kev sib txuas lus nrog lub chaw ua haujlwm. Yog tias cov ntsiab lus inhibitor siab dua li ntawm cov substrate, lub complex enzyme inhibitor yog tsim. Thaum ib lub hom phiaj ntxiv, qhov piv yuav hloov. Yog li ntawd, tus inhibitor yuav raug yuam tawm. Piv txwv li, succinate ua lub substrate rau succinate dehydrogenase. Inhibitors yog oxaloacetate lossis malonate. Kev sib tw cuam tshuam yog suav tias yog cov khoom siv tshuaj tiv thaiv. Feem ntau lawv zoo ib yam li cov substrate. Piv txwv li, rau cov piam thaj-6-phosphate, cov khoom yog qabzib. Lub substrate yuav yog qabzib-6 phosphate. Non-competitive inhibition tsis cuam tshuam qhov zoo sib xws ntawm cov khoom. Ob lub inhibitor thiab substrate tuaj yeem khi rau lub enzyme tib lub sijhawm. Nyob rau hauv cov ntaub ntawv no, ib tug tshiab compound yog tsim. Nws yog ib qho complex-enzyme-substrate-inhibitor. Thaum lub sij hawm sib cuam tshuam, lub chaw ua haujlwm raug thaiv. Qhov no yog vim kev khi ntawm cov inhibitor rau catalytic site ntawm AC. Ib qho piv txwv yog cytochrome oxidase. Rau cov enzyme no, oxygen ua raws li lub substrate. Hydrocyanic acid ntsev yog inhibitors ntawm cytochrome oxidase.
Txoj cai tswj hwm
Qee zaum, ntxiv rau qhov chaw ua haujlwm uas txiav txim siab qhov tshwj xeeb ntawm cov enzyme, muaj ib qho txuas ntxiv. Nws yog ib qho allosteric tivthaiv. Yog tias tus activator ntawm tib lub npe khi rau nws, kev ua haujlwm ntawm cov enzyme nce. Yog hais tias tus inhibitor reacts nrog lub allosteric center, ces cov kev ua ntawm cov tshuaj yuav txo tau raws li. Piv txwv li, adenylate cyclase thiabGuanylate cyclase yog cov enzymes nrog kev tswj hwm ntawm hom allosteric.
