Factors that Affect Enzyme Action | 影响酶作用的因素

📚 Factors that Affect Enzyme Action | 影响酶作用的因素

Enzymes are globular proteins that act as biological catalysts, lowering activation energy and accelerating reactions without being consumed. Their activity is highly sensitive to environmental conditions and to the concentrations of molecules that bind to them. For Cambridge A-Level Biology, you must explain how temperature, pH, enzyme concentration, substrate concentration, inhibitors, cofactors and immobilisation influence the rate of an enzyme-catalysed reaction, and you must link these effects to protein structure and the active site.

酶是球状蛋白质，作为生物催化剂，可降低活化能并加速反应，而自身不被消耗。酶活性对周围环境以及与酶结合的分子浓度高度敏感。在剑桥 A-Level 生物学中，你必须解释温度、pH、酶浓度、底物浓度、抑制剂、辅因子和固定化如何影响酶促反应速率，并将这些影响与蛋白质结构和活性部位联系起来。

1. Enzyme Action and the Active Site | 酶的作用与活性部位

An enzyme has a specific three-dimensional active site formed by folding of its polypeptide chain. The substrate fits into this active site either by the lock-and-key model or by the induced-fit model, in which binding changes the shape of the enzyme slightly to strain bonds and lower the activation energy.

酶具有由多肽链折叠形成的特定三维活性部位。底物通过锁钥模型或诱导契合模型与活性部位结合；诱导契合中，底物结合会使酶形状略微改变，从而拉扯化学键并降低活化能。

Any factor that changes the shape, charge or flexibility of the active site can reduce the formation of enzyme-substrate complexes and therefore reduce the rate of reaction. The rate of an enzyme-catalysed reaction is usually measured as the initial rate, before substrate is depleted or product accumulates.

任何改变活性部位形状、电荷或柔韧性的因素都会减少酶-底物复合物的形成，从而降低反应速率。

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