Enzymes: Biological Catalysts | 酶：生物催化剂

📚 Enzymes: Biological Catalysts | 酶：生物催化剂

Enzymes are biological catalysts that accelerate the hundreds of chemical reactions happening inside living cells. Without enzymes, these reactions would be far too slow to sustain life.

酶是生物催化剂，能够加速活细胞内发生的数百种化学反应。如果没有酶，这些反应将慢得无法维持生命。

In the Edexcel IGCSE Biology syllabus, enzymes are a core topic that connects with nutrition, respiration and biotechnology. Understanding their structure, how they work and what changes their activity is essential for exam success.

在 Edexcel IGCSE 生物课程大纲中，酶是与营养、呼吸和生物技术相互交叉的核心主题。理解其结构、作用方式以及哪些因素会改变其活性，对于考试取得成功至关重要。

1. What Are Enzymes? | 什么是酶？

Enzymes are proteins. They are made from long chains of amino acids folded into a unique three-dimensional shape. This shape is determined by the order of amino acids and by the weak bonds that form between different parts of the chain.

酶是蛋白质。它们由折叠成独特三维形状的长链氨基酸构成。这一形状由氨基酸的顺序以及链的不同部分之间形成的弱键决定。

Enzymes are catalysts, meaning they speed up chemical reactions without being used up or permanently changed. One enzyme molecule can catalyse many reactions, so only small quantities are needed.

酶是催化剂，意味着不会在加速化学反应的同时被消耗或永久改变。一个酶分子可以催化许多次反应，因此仅需要少量即可。

2. The Active Site | 活性位点

Each enzyme contains a specific region called the active site. The shape of the active site is complementary to the shape of the substrate, the reactant that the enzyme acts upon. The substrate binds to the active site to form an enzyme-substrate complex.

每种酶都含有一个称为活性位点的特定区域。活性位点的形状与底物——即酶作用的反应物——的形状互补。底物与活性位点结合，形成酶-底物复合物。

Enzyme + Substrate → Enzyme-Substrate Complex → Enzyme + Products

This complex lowers the activation energy of the reaction. As a result, reactions that would normally take a long time can occur in milliseconds under enzyme control.

该复合物降低了反应的活化能。因此，原本需要很长时间的反应能在酶的调控下于毫秒内完成。

3. Lock and Key Model | 锁钥模型

The lock and key model explains enzyme specificity. The enzyme is the lock, and the substrate is the key. Only a substrate with the exact correct shape can fit into the active site, just as only the correct key can open a lock.

锁钥模型解释了酶的专一性。酶是锁，底物是钥匙。只有形状精确匹配的底物才能嵌入活性位点，就像只有正确的钥匙

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