均相酶反應(yīng)動(dòng)力學(xué)ppt課件(編輯修改稿)
2025-02-01 09:11 本頁(yè)面
【文章內(nèi)容簡(jiǎn)介】 ??????????Impa p pmpKIVv][1,we can get, ][]][[][]][[][]][[][]][[ES IIESEIIEKES ISEIESSEKIm ?????][][][][][ 0 E S IEIESEE ????][2 ESkv p ?The effect of nonpetitive inhibitions is a reduction in with same MichaelisMenten constant. app,mVHigh substrate concentration would not overe nonpetitive inhibitions. Other reagents need to be added to block binding of it to the enzyme. Plots on Nonpetitive Inhibitions 反競(jìng)爭(zhēng)性抑制 (Unpetitive Inhibitions) S E I + E S E S I X P 這種抑制劑僅能與 ES復(fù)合物 結(jié)合，而與 游離酶 不能直接結(jié)合。 E + S [ES] + I E + P [ESI] Km’ KI With similar equations and derivatives as before, ][][,SKSVva p pma p pm???where and . ???????? ????Ima p pmKIKK][1,???????? ??ImappmKIVv][1,we can get, ][]][[][]][[ES IIESKESSEKIm ???][2 ESkv ?][][][][ 0 S E IESEE ???Plots on Unpetitive Inhibitions Obviously, the effect of unpetitive inhibitions is a reduction in both and , and the result is a reduction in reaction rate. appmK ,? appmV ,各種抑制的比較 競(jìng)爭(zhēng)性抑制 非競(jìng)爭(zhēng)性抑制 反競(jìng)爭(zhēng)性抑制 例 在含有相同酶濃度的五個(gè)反應(yīng)物系中，分別加入不同濃度的底物，并測(cè)定其初始速率，然后再在同樣五個(gè)反應(yīng)物系中分別加入濃度為 101mmol/L的抑制劑，并測(cè)其初始的反應(yīng)速率，其數(shù)據(jù)見下表。 底物初始濃度mmol/L 無(wú)抑制時(shí)速率mmol/(L﹒ min) 有抑制時(shí)速率mmol/(L﹒ min) 28 18 36 24 43 30 63 51 74 63 試根據(jù)上述數(shù)據(jù)決定其抑制類型及動(dòng)力學(xué)參數(shù)值。 解：將上述實(shí)驗(yàn)數(shù)據(jù)分別取其倒數(shù)，以 1/v1/[S]作圖，得到下圖的兩條直線，他們?cè)诳v軸上有一共同點(diǎn)，這表明該抑制為競(jìng)爭(zhēng)性抑制。 1/Vsi1/[S] 1/Vs01/[S] Vmax=1/=100 mmol/L Km=1/()= mmol/L KmI=1/()= mmol/L KI= mmol/L 底物抑制 (Substrate Inhibitions) 高濃度的底物會(huì)抑制 一些酶促反應(yīng)。 E E S + S S E S S X P E + S [ES] + S E + P [ESS] Km’ KSI k+2 With similar equations and derivations as before, SImmSImmKSSKSVKSSKVv21][][][][][????????][]][[][]][[E S SSESKESSEKSIm ???][][][][ E S SESEE ???0][ESkv 2??SIm ]][[][][ ][39。][ K SESE S SSESKE ??變換方程得： Then, we can get, SI][][39。][][KSSKEESm ???10][m a x 02 EkV ?? ]/[m a x 02 EVk ??即為 , . 即 , 則 或 即 , , 則 或 Discussions about Substrate Inhibitions ? 反應(yīng)速率最大時(shí) ,其底物濃度為 : 0?][SddvSIm KKS ??m a x][ 12 ???SImma ppKKVvm a x ,? 低物濃度很低時(shí) , 1??SIKS ][ mmmmKSSVSKVv?????? ][][][1即為沒有抑制劑存在情況下的米氏方程 . ][SVKVv mmm111 ???? 底物濃度很高時(shí) , 1??][ 39。SKmSImKSVv][?? 1底物的抑制性就很明顯 . SImm KVSVv][?? 11At low substrate concentration, the rate expression approximates to the MichaelisMenten equation, then the curve in doublereciprocal (雙倒數(shù) )plot is parallel(平行 ) with the linear line denoted the instance without substrate inhibition. Similarly, at high substrate concentration, the curve in doublereciprocal plot is in hyperbolic(雙曲線 ) mode. Plots on Substrate Inhibitions 產(chǎn)物抑制 (product inhibitions) E E S E P P S P E + S + P [ES] E + P [EP] Km’ KP k+2
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