Lock vs Key vs Induced Fit
Enzymes yog lub npe hu ua biological catalysts, uas yog siv nyob rau hauv yuav luag txhua cellular cov tshuaj tiv thaiv, nyob rau hauv cov kab mob. Lawv tuaj yeem nce tus nqi ntawm cov tshuaj tiv thaiv biochemical, yam tsis muaj enzyme hloov nws tus kheej los ntawm cov tshuaj tiv thaiv. Vim nws reusability, txawm ib tug me me concentration ntawm ib tug enzyme yuav ua tau zoo heev. Tag nrho cov enzymes yog cov proteins thiab globular nyob rau hauv cov duab. Txawm li cas los xij, zoo li tag nrho lwm cov catalyst, cov khoom siv roj ntsha no tsis hloov cov khoom kawg, thiab lawv tsis tuaj yeem ua rau muaj tshwm sim. Tsis zoo li lwm cov catalyst ib txwm, enzymes catalyze tsuas yog ib hom kev thim rov qab, yog li hu ua cov tshuaj tiv thaiv tshwj xeeb. Txij li thaum, cov enzymes yog cov proteins; lawv tuaj yeem ua haujlwm nyob rau hauv ib qho kub, siab thiab pH ntau yam. Feem ntau cov enzymes catalyze cov tshuaj tiv thaiv los ntawm kev ua cov 'enzyme- substrate complexes'. Nyob rau hauv cov complexes, lub substrate khi feem ntau nruj rau enzymes sib haum mus rau lub xeev hloov. Lub xeev no muaj lub zog qis tshaj plaws; li no nws yog qhov ruaj khov dua li qhov kev hloov pauv ntawm cov tshuaj tiv thaiv uncatalysed. Yog li ntawd, ib qho enzyme txo qhov ua kom lub zog ntawm cov tshuaj lom neeg, uas nws catalyzes. Ob txoj kev xav tseem ceeb yog siv los piav qhia yuav ua li cas enzyme-substrate complexes tsim. Lawv yog kev ntsuas xauv-thiab-qhov tseem ceeb thiab induced-fit theory.
Lock-and-Key Model
Enzymes muaj cov duab meej heev, uas suav nrog lub cleft lossis hnab ris hu ua cov chaw nquag. Hauv qhov kev xav no, lub substrate haum rau hauv qhov chaw nquag xws li tus yuam sij rau hauv lub xauv. Feem ntau ionic bonds thiab hydrogen bonds tuav lub substrate nyob rau hauv lub active sites tsim lub enzyme- substrate complex. Thaum nws tau tsim, enzyme catalyzes cov tshuaj tiv thaiv los ntawm kev pab hloov cov substrate, xws li cais nws sib nrug los yog hauv ob sab phlu ua ke. Qhov kev xav no nyob ntawm qhov kev sib cuag raug ua los ntawm cov chaw nquag thiab substrate. Yog li ntawd, qhov kev xav no yuav tsis raug tag nrho, tshwj xeeb tshaj yog thaum muaj kev sib txuam ntawm cov substrate molecules koom nrog.
Induced-Fit Model
Nyob rau hauv txoj kev xav no, qhov chaw nquag hloov nws cov duab los nthuav cov substrate molecule. Lub enzyme, tom qab khi nrog ib qho substrate, siv nws cov duab zoo tshaj plaws. Yog li ntawd, cov duab ntawm cov enzyme yog cuam tshuam los ntawm substrate zoo li cov duab ntawm lub hnab looj tes cuam tshuam los ntawm txhais tes hnav. Tom qab ntawd, nyob rau hauv lem, lub enzyme molecule distorts lub substrate molecule, straining lub bonds, thiab ua rau lub substrate tsis ruaj, yog li txo lub zog activation ntawm cov tshuaj tiv thaiv. Txij li thaum, lub zog ua kom qis qis, cov tshuaj tiv thaiv tshwm sim ntawm qhov nrawm nrawm tsim cov khoom. Tom qab cov khoom raug tso tawm, qhov chaw ua haujlwm ntawm cov enzyme ces rov qab mus rau nws cov duab qub thiab, khi cov substrate molecule tom ntej.
Qhov txawv ntawm Xauv-thiab-Key thiab Induced- Haum yog dab tsi?
• Induced-fit theory is a modified version of lock-and-key theory.
• Tsis zoo li qhov kev xav ntawm Lock-and-key, induced-fit theory tsis yog nyob ntawm qhov kev sib cuag raug tsim los ntawm qhov chaw nquag thiab substrate.
• Hauv Induced- haum txoj kev xav, cov enzyme zoo li cuam tshuam los ntawm lub substrate whereas, nyob rau hauv Lock-and-key theory, lub substrate zoo yog cuam tshuam los ntawm lub enzyme.
• Nyob rau hauv Xauv-thiab-qhov tseem ceeb txoj kev xav, cov chaw ua haujlwm muaj cov duab meej, whereas hauv Induced- haum txoj kev xav, qhov chaw nquag pib tsis muaj cov duab meej, tab sis tom qab lub site zoo li tsim raws li lub substrate., uas yuav khi.
