Lub mechanism ntawm qhov kev txiav txim ntawm enzymes

Enzymes (enzymes) - ib tug siab molecular yuag organic tebchaw uas muaj protein ntau cov xwm, uas muaj nyob rau hauv tus kab mob ib lub luag hauj lwm ntawm lom catalysts.

Lub mechanism ntawm qhov kev txiav txim ntawm enzymes

Elucidation ntawm lub mechanisms lwm lub catalytic kev txiav txim ntawm enzymes, yog ib tug ntawm cov yuav tsum muaj teeb meem thiab tam sim no muaj teeb meem tsis tsuas enzymology, tab sis niaj hnub biochemistry thiab molecular biology.

Ntev ua ntej lub enzymes los ua muaj ntshiab thiab elucidated lawv qhov, tau ua ntseeg tias tseem ceeb heev rau enzymatic txheej txheem muaj ib tug coupling ntawm enzyme mus rau lub substrate. Npaj siab mus nrhiav ib txoj compound ntawm lub enzyme nrog lub substrate rau ib ntev lub sij hawm tsis ua rau kev vam meej, li no ua yog labile, nws sai heev decomposes. Siv spectroscopy txoj kev tau ua rau nws tau kom paub tias cov enzyme-substrate ceg rau catalase, peroxidase, haus dej cawv dehydrogenase, flavinzavisimyh enzymes.

Cov kev X-ray tsom tau tso cai kom tau ib tug ntau ntawm cov ntaub ntawv tseem ceeb nyob rau hauv cov qauv thiab cov catalytic mechanisms ntawm kev txiav txim ntawm enzymes. Qhov no txoj kev siv los mus tsim kom muaj ib tug kev twb kev txuas substrate analogues nrog enzymes lysozyme thiab chymotrypsin.

Ib txhia ncaj pov thawj rau lub hav zoov ntawm enzyme-substrate ceg kev tswj kom tau mus rau qhov twg ib yam ntawm cov catalytic voj voog ua sawv ntawm lub enzyme yog ua txhua yam rau lub substrate los ntawm ib tug covalent daim ntawv cog lus. Ib qho piv txwv yog cov tshuaj tiv thaiv ntawm hydrolysis ntawm n-nitrophenyl acetate tshwmsim los ntawm chymotrypsin. Thaum tov nrog enzyme chymotrypsin ether yog acetylated nyob rau hydroxyl pab pawg neeg ntawm cov reactive serine residue. Qhov no yuav tsis nyob ntev yog ceev ceev, tab sis atsetilhimotripsina hydrolysis nrog lub tsim ntawm acetate thiab dawb lub chymotrypsin yog npaum li cas qeeb qeeb. Yog li ntawd atsetilhimotripsin accumulates, uas yog yooj yim nrhiav tau nyob rau hauv lub xub ntiag ntawm n-nitrophenylacetate.

Lub xub ntiag ntawm lub enzyme substrate nyob rau hauv muaj pes tsawg leeg tau "catch" los ntawm hloov lwm lub tsev EU tsis ruaj tsis khov complex nyob rau hauv ib tug tsis nquag daim ntawv, piv txwv li, los ntawm kev kho mob nrog rau cov enzyme-substrate complex ntawm sodium borohydride muaj ib tug muaj zog txo nyhuv. Xws li ib tug complex nyob rau hauv daim ntawv ntawm ruaj covalent derivative twb ntes tau nyob rau hauv lub enzyme aldolase. Nws pom hais tias lub substrate ua num ua ke nrog ib tug molecule e-amino pab pawg neeg ntawm lysine.

Lub substrate reacts nrog cov enzyme nyob rau hauv ib tug ib feem uas yog hu ua tus active chaw ntawm lub enzyme los yog lub active cheeb tsam.

Nyob rau hauv lub active chaw, los yog cov tub ntxhais, to taub hais tias feem enzyme protein molecule uas yog kev cob cog rua rau lub substrate (thiab cofactors) thiab ua rau lub enzymatic thaj chaw ntawm lub molecule. Lub active site txiav txim seb tus tseem thiab catalytic ua si ntawm lub enzyme thiab yuav tsum muaj ib yam teeb, teeb meem qauv siv tau rau ze mus kom ze thiab kev sib txuas lus nrog ib tug substrate molecule, los yog nws qhov chaw ncaj qha kev koom tes nyob rau hauv cov tshuaj tiv thaiv.

Ntawm cov functional pawg yog txawv nyob rau hauv cov "catalytically active" feem ntawm lub enzyme thiab ntawm txoj kev feem muab ib lub sib ze (lub thwj toob ntawm substrate rau lub enzyme) - qhov thiaj li hu ua nawj, los yog "thauj tog rau nkoj" (los yog adsorption ntawm lub enzyme active site).

Lub mechanism ntawm qhov kev txiav txim ntawm enzymes piav txog cov kev tshawb xav ntawm lub Michaelis-Menten kab zauv. Raws li no ziag no, cov txheej txheem yuav siv sij hawm qhov chaw nyob rau hauv plaub theem.

Lub mechanism ntawm qhov kev txiav txim ntawm enzymes: Kuv Theem

Nruab nrab ntawm lub substrate (C) thiab enzyme (E) ib tug kev twb kev txuas tshwm sim - tsim EU enzyme-substrate complex, nyob rau lub Cheebtsam sib thooj, los ntawm covalent, ionic, dej thiab lwm yam bonds.

Lub mechanism ntawm qhov kev txiav txim ntawm enzymes: IІ theem

Lub substrate yog raug mus rau lub txuas enzyme yog tshuab txais thiab yuav muaj nyob rau hauv cov tshuaj ntawm lub EU catalysis.

Lub mechanism ntawm qhov kev txiav txim ntawm enzymes: IІI theem

EU cog lus catalysis. Qhov no kev tshawb xav yog txaus siab los ntawm kev sim kev tshawb fawb.

Thaum kawg, IV theem yog yus muaj los ntawm qhov kev tso tawm ntawm lub enzyme molecules E thiab F. Cov kab sab ntawm transformations ntawm cov khoom yuav tsum tso tawm kom pom raws li cov tshuaj tiv thaiv: E + S - EU EU - * - E + P.

Cov tseem ntawm enzyme txiav txim

Txhua enzyme ua rau ib tug kev substrate los yog pab pawg neeg ntawm tshuaj, uas yog zoo xws li cov nyob rau hauv kev teeb tsa. Tseem ntawm enzymatic vim kev zoo sib thooj ntawm lub active site configuration thiab substrate. Thaum lub sij hawm sib tham ntawm enzyme-substrate tsim complex.