EQUILIBRIUM AND RATE CONSTANTS FOR INTERCONVERSION OF 2 CONFORMATIONS OF ALPHA-CHYMOTRYPSIN - EXISTENCE OF A CATALYTICALLY INACTIVE CONFORMATION AT NEUTRAL PH
EQUILIBRIUM AND RATE CONSTANTS FOR INTERCONVERSION OF 2 CONFORMATIONS OF ALPHA-CHYMOTRYPSIN - EXISTENCE OF A CATALYTICALLY INACTIVE CONFORMATION AT NEUTRAL PH
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DOI：
10.1016/0022-2836(71)90294-4
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发表时间：
1971-01-01
影响因子：
5.6
通讯作者：
REQUENA, Y
中科院分区：
文献类型：
--
作者：
FERSHT, AR;REQUENA, Y
α-胰凝乳蛋白酶在25°C、较大pH范围的水溶液中至少存在两种构象，一种是活性构象，另一种是非活性构象。pH值高于9时，酶主要以无活性形式存在，这一点从Hess的实验中众所周知（Hess, McConn, Ku & McConkey, 1970）。然而，在目前的研究中表明，这种构象在总酶浓度的15 - 20%时呈中性。两种构象的相互转化是缓慢的；这可能导致前稳态动力学中的伪影，这可能被误解为中间产物的证据。il -16非活性构象的pKaof为7.94±0.1。
α-Chymotrypsin exists in at least two conformations, one active and one inactive, in aqueous solution at 25 °C over a wide pH range. Above pH 9 the enzyme exists as predominantly the inactive form, as is well known from the experiments of Hess (Hess, McConn, Ku & McConkey, 1970). However, it is shown in the present study that this conformation is present at neutrality as 15 to 20% of the total enzyme concentration. The interconversion of the two conformations is slow; this may lead to artifacts in pre-steady-state kinetics which could be misinterpreted as evidence for intermediates. The pKaof Ile-16 in the inactive conformation is calculated to be 7.94 ± 0.1.