Lub active site ntawm lub enzyme: cov qauv, cov khoom. Leej twg nrhiav tau lub active site ntawm lub enzyme? Yuav ua li cas yog hu ua tus active site ntawm lub enzyme?

Peb muaj tag nrho cov hnov ntawm enzymes, tab sis nws yog tsis zoo li hais tias txhua tus ntawm peb kom huv si paub xyov yuav ua li cas cov tshuaj yog cov txheej txheem ntawm, thiab vim li cas lawv yuav tsum tau. Qhov tsab xov xwm yuav pab kom to taub cov qauv thiab cov kev khiav dej num ntawm enzymes (enzymes) nyob rau hauv Feem ntau, thiab lawv active chaw zov me nyuam nyob rau hauv particular.

Keeb kwm kev tshawb fawb

Nyob rau hauv Hlis Ntuj xyoo 1833, Fabkis chemist Anselme Payen paub thiab piav qhia txog lub zog ntawm cov enzyme amylase.

Ib tug ob peb xyoos tom qab ntawd, Louis Pasteur, kawm hloov dua siab tshiab uas muaj suab thaj rau hauv dej cawv uas cov poov xab, pom tias tias tus txheej txheem no yog vim cov tshuaj uas ua tau cov poov xab.

Thaum kawg ntawm lub XIX xyoo pua physiologist Villi Kyune thawj coined lub sij hawm "enzyme".

German Eduard Buchner nyob rau hauv 1897 qhia thiab piav zymase - enzyme complex uas catalyzes lub hloov dua siab tshiab ntawm sucrose rau hauv ethanol cov tshuaj tiv thaiv. Nyob rau hauv cov xwm zymase nyob rau hauv zoo kawg kom muaj nuj nqis nyob rau hauv lub poov xab.

Nws tsis yog lub npe hu thaum twg thiab leej twg qhib lub active site ntawm lub enzyme. Qhov no discovery yog rho nrog Nobel laureate chemist Edaurdu Buchner, American biologist James Sumner thiab lwm yam zoo-paub zaum uas ua hauj lwm nyob rau hauv txoj kev tshawb no ntawm enzymatic catalysis.

General ntaub ntawv hais txog enzymes

Cov txheejtxheem uas enzymes - tshuaj uas muaj protein ntau cov xwm, uas ua zog nyob rau hauv uas muaj sia nyob catalysts ntawm tshuaj tshua. Lub enzyme muaj feem uas tsis ncaj qha coj ib feem nyob rau hauv nws, lub ndlwg ntawm cov tshuaj tiv thaiv yuav muab ib tug active chaw ntawm lub enzyme.

Ntawm no yog ib co ntawm cov yam ntxwv ntawm enzymes:

1) Efficiency. Ib tug me me ntawm lub hauv paus txaus leeb ib tug tshuaj cov tshuaj tiv thaiv nyob rau hauv 10 ⁶ lub sij hawm.

2) things. Ib enzyme tsis yog universal catalyst ntawm tej tshuaj tiv thaiv nyob rau hauv lub cell. Rau enzyme qhia tseem kev txiav txim ntawm no: txhua tus enzyme catalyzes tsuas yog ib los yog ob peb zoo sib xws tshua nrog substrates (lub reactant pub), tab sis lwm yam tshuaj reagents rau qhov xwm tib yam, cov enzyme tej zaum yuav puas. Sis nrog tus uas tsim nyog substrates thiab ntxiv acceleration ntawm cov tshuaj tiv thaiv yuav muab ib tug active chaw ntawm lub enzyme.

3) Clear ua. Lub enzyme ua si nyob rau hauv lub cell yog lossi hloov los ntawm tsis rau siab.

4) Concentration ntawm tej yam enzymes nyob rau hauv lub cell tsis yog tas li thiab tej zaum yuav txawv nyob ntawm seb cov sab nraud tej yam kev mob. Tej enzymes hauv ib hu ua inducible.

kev faib ntawm enzymes

Nyob rau hauv nws cov qauv, cov enzymes yuav tau muab faib mus rau hauv tej yam yooj yim thiab complex. Tej yam yooj yim xws li heev dua lwm yam ntawm cov amino acid residues, muaj txoj uas tsis yog-protein pab pawg neeg ntawm tshuaj. Complex hu ua coenzymes.

Los ntawm hom ntawm enzyme catalysed tshua raug muab faib mus rau hauv:

1) Oxidoreductases (catalyze redox tshua).

2) Transferases (pauv mus rau tej pawg neeg nyias ntawm atoms).

3) Lyases (muab siab npuab tshuaj bonds).

4) lipase (kev twb kev txuas daim ntawv nyob rau hauv lub tshua vim lub zog ntawm ATP).

5) Isomerases (uchuvstvuyut tshua interconversion ntawm isomers).

6) Hydrolases (catalyze tshuaj los ntawm kev zom nrog bonds).

qauv enzyme

Enzyme - ib tug complex peb-dimensional qauv, uas yog muaj mas amino acid residues. Tsis tas li ntawd muaj yog ib tug prosthetic pab pawg neeg - ib feem ntawm uas tsis yog-protein xwm, txuam nrog cov amino acid residues.

Enzymes - mas globular proteins uas yuav ua ke nyob rau hauv txoj systems. Ib yam li lwm proteinaceous tshuaj, enzymes yog denatured los ntawm nce lub kub los yog los ntawm raug rau ib txhia tshuaj. Thaum lub sij hawm denaturation txawv tertiary enzyme qauv thiab yog li lub zog ntawm cov active chaw ntawm lub enzymes. Raws li ib tug tshwm sim, lub enzyme ua si txo dramatically.

Tshwmsim substrate yog feem ntau npaum li cas me dua cov enzyme nws tus kheej. Qhov yooj yim enzyme muaj rau caum amino acid residues, thiab nws active center - tsuas yog ob tug.

Muaj enzymes catalytic site amino acids uas yog tsis uas muaj tuaj, thiab ib tug organic prosthetic pab pawg neeg, los yog (ntau zaus) inorganic keeb kwm - cofactor.

Lub tswvyim ntawm cov active site

Tsuas yog ib feem me me ntawm cov enzyme ncaj qha kev koom tes nyob rau hauv tshuaj tshua. Qhov no yog ib feem ntawm lub enzyme hu ua lub active site. Lub active site ntawm lub enzyme - ib tug lipid, ib tug ob peb amino acid residues los yog prosthetic pab pawg neeg, uas uake mus rau ib tug substrate thiab catalyzes cov tshuaj tiv thaiv. Cov amino acid seem ntawm lub active qhov chaw yuav mus rau tej amino acids - ncov qaumteb qabteb, nonpolar, them, uas muaj ntxhiab uncharged.

Lub active enzyme chaw (qhov no lipid, amino acids thiab lwm yam uas muaj peev xwm ntawm reacting nrog lub reagents) - qhov tseem ceeb tshaj yog ib feem ntawm lub enzyme, tsis muaj cov tshuaj yuav puas.

Feem ntau, cov enzyme molecule muaj tsuas yog ib yam kom nquag plias site, losis tswvyim dabtsi nrog ib tug los yog ntau tshaj zoo xws li cov reagents. Cov amino acid seem ntawm lub active chaw tsim hydrogen, hydrophobic los yog covalent bonds, txoj kev ua ib qho enzyme-substrate complex.

Tus qauv ntawm lub active chaw

Lub active site ntawm enzymes, yooj yim thiab ua yog ib lub hnab tshos los yog qhov. Qhov no qauv ntawm lub active chaw ntawm lub enzyme yuav tsum yoog geometrically thiab electrostatically lub substrate, txij li thaum ib tug hloov nyob rau hauv lub tertiary qauv ntawm cov enzyme tej zaum yuav hloov lub active site.

Binding thiab catalytic center - qhov chaw ntawm lub active chaw ntawm lub enzyme. Obviously, cov losis tswvyim dabtsi site "tshev" substrate compatibility, thiab yog txuam nrog nws, thiab lub catalytic center yog ncaj qha mus muab kev koom tes nyob rau hauv cov tshuaj tiv thaiv.

Thwj toob ntawm tus nquag chaw ntawm lub substrate

Nyob rau hauv thiaj li yuav piav li cas lub active site ntawm lub enzyme txuam nrog ib tug kev reagent, ob peb theories tau npaj siab. Cov feem nrov ntawm lawv - Fisher tus txoj kev xav, nws yog ib lub hom phiaj ntawm "xauv thiab qhov tseem ceeb". Fisher pom hais tias muaj yog ib qho enzyme hom phiaj haum rau txhua substrate nyob rau hauv nws lub cev thiab tshuaj zog. Tom qab tsim ntawm tej kev hloov kho tsis tshwm sim enzyme-substrate complex.

Lwm American kws ntawv - Daniel Koshland - ntxiv Fisher assumption ntawm txoj kev tshawb xav hais tias cov active site ntawm lub enzyme yuav hloov tau lawv lub conformation li ntev raws li tsis haum ib tug substrate.

Lub kinetics ntawm enzymatic tshua

Nta enzymatic cov tshuaj tiv thaiv yog kawm biochemistry private sector - enzyme kinetics. Qhov no xyov science tshawb fawb ntawm cov tshuaj uas sib txawv ntau ntawm enzymes thiab substrates, lub dependence ntawm cov tshuaj tiv thaiv tus nqi rau qhov kub thiab txias nyob rau hauv lub cell thiab lub zog ntawm cov active site ntawm enzymes nyob rau hauv lub cev thiab tshuaj tsis muaj qhov nruab nrab.

Enzyme kinetics ua hauj lwm cov tswv yim xws li cov tshuaj tiv thaiv tus nqi, kom muaj zog, ua kom teeb meem, molecular kev ua si, kev ua si thiab lwm tus neeg. Xav txog ib co ntawm cov tswv yim.

Uas muaj yog ib tug lom cov tshuaj tiv thaiv, cov reagents tsim nyog mus rau cov hloov ib co muaj zog. No lub zog yog hu ua qhov ua kom muaj zog.

Qhov sib ntxiv ntawm lub enzyme mus rau lub reactants los txo qhov ua kom muaj zog. Ib txhia tshuaj hnov mob rau tsis muaj kev koom tes los ntawm enzymes, txij li thaum qhov ua kom lub zog yog siab dhau heev lawm. Cov tshuaj tiv thaiv equilibrium tsis ceev nrog rau qhov sib ntxiv ntawm lub enzyme.

Cov tshuaj tiv thaiv tus nqi - tus nqi ntawm cov tshuaj tiv thaiv cov khoom nyob los yog zoo nyob rau hauv lub chav tsev lub sij hawm.

Nyob tos ntawm cov tshuaj tiv thaiv tshaj tawm rau substrate concentration dimensionless lub cev kom muaj nuj nqis characterizes - Michaelis qhov.

Molecular ua - tus xov tooj ntawm substrate molecules uas hloov dua siab tshiab rau ib tug qauv ntawm enzyme ib chav tsev lub sij hawm.