📚 Enzymes: Biological Catalysts in IGCSE Science | IGCSE 科学中的酶：生物催化剂
In every living organism, thousands of chemical reactions occur every second to sustain life. From breaking down food in the digestive system to synthesising new proteins for cell repair, these reactions must happen at precisely the right speed under mild conditions. Without enzymes, most of these vital processes would be far too slow to support life as we know it. Understanding enzymes is fundamental not only to biology but also to chemistry, where concepts of reaction rates, activation energy, and catalysis converge. This article provides a comprehensive exploration of enzymes aligned with the Edexcel IGCSE Science syllabus, covering their structure, mechanism of action, factors affecting activity, and real-world applications.
在每一个生物体内，每秒都有成千上万的化学反应在维持着生命。从消化系统中分解食物到合成用于细胞修复的新蛋白质，这些反应必须在温和条件下以精确的速度进行。如果没有酶，这些至关重要的过程大多会过于缓慢，无法维持我们所知的生命。理解酶不仅是生物学的基础，也是化学的基础，反应速率、活化能和催化作用等概念在此交汇。本文全面探讨酶的相关知识，内容紧扣 Edexcel IGCSE 科学教学大纲，涵盖酶的结构、作用机制、影响活性的因素以及实际应用。
1. What Are Enzymes? | 什么是酶？
Enzymes are globular proteins that act as biological catalysts. A catalyst is any substance that speeds up a chemical reaction without being used up or permanently changed in the process. In living cells, enzymes lower the activation energy required for metabolic reactions to proceed, enabling them to occur rapidly at body temperature. Each enzyme is highly specific, typically catalysing only one type of reaction or acting on a single substrate. This specificity arises from the unique three-dimensional shape of the enzyme's active site, which is determined by the sequence of amino acids in its polypeptide chain.
酶是作为生物催化剂的球状蛋白质。催化剂是指任何能够加速化学反应而自身在过程中不被耗尽或永久改变的物质。在活细胞中，酶降低代谢反应所需的活化能，使其能在体温条件下迅速进行。每种酶都具有高度特异性，通常只催化一种类型的反应或作用于单一底物。这种特异性源于酶活性位点独特的三维形状，而该形状由其多肽链中氨基酸的序列决定。
2. Enzyme Structure and the Active Site | 酶的结构与活性位点
All enzymes possess an active site – a specialised region with a specific shape and chemical environment. The active site is formed by the folding of the polypeptide chain, creating a pocket or cleft on the enzyme's surface. The amino acid side chains within the active site establish precise chemical interactions – including hydrogen bonds, ionic bonds, and hydrophobic interactions – that bind the substrate and facilitate the reaction. The remainder of the enzyme protein provides structural support and maintains the correct conformation of the active site.
所有酶都具有一个活性位点——一个具有特定形状和化学环境的特化区域。活性位点由多肽链的折叠形成，在酶的表面创造出一个口袋或裂隙。活性位点内的氨基酸侧链建立精确的化学相互作用——包括氢键、离子键和疏水相互作用——结合底物并促进反应。酶蛋白的其余部分提供结构支撑，维持活性位点的正确构象。
The lock-and-key model was the earliest explanation of enzyme specificity, proposing that the active site has a fixed, rigid shape that exactly matches the shape of its substrate, just as a key fits into a specific lock. However, this model is now considered oversimplified. The induced-fit model provides a more accurate description: the active site is flexible and undergoes a conformational change when the substrate binds, moulding itself around the substrate to achieve a tighter fit. This induced fit stresses key bonds in the substrate, lowering the activation energy more effectively.
锁钥模型是对酶特异性的最早解释，认为活性位点具有固定、刚性的形状，恰好与底物的形状匹配，就像一把钥匙插入特定的锁一样。然而，该模型现在被认为过于简化。诱导契合模型提供了更准确的描述：活性位点是灵活的，当底物结合时会发生构象变化，围绕底物塑造自身以实现更紧密的契合。这种诱导契合对底物中的关键化学键施加应力，更有效地降低活化能。
3. How Enzymes Lower Activation Energy | 酶如何降低活化能
In any chemical reaction, reactant molecules must overcome an energy barrier before products can form. This energy barrier is called the activation energy (Eₐ). Without a catalyst, many biological reactions would require temperatures far exceeding body temperature to provide sufficient kinetic energy for molecules to collide successfully. Enzymes lower the activation energy by providing an alternative reaction pathway. They do this by binding the substrate, orienting reactant molecules favourably, and stabilising the transition state – the high-energy intermediate state between reactants and products. By reducing Eₐ, a far greater proportion of substrate molecules possess sufficient energy to react at any given temperature, dramatically increasing the reaction rate.
在任何化学反应中，反应物分子必须克服一个能量障碍才能形成产物。这个能量障碍称为活化能(Eₐ)。如果没有催化剂，许多生物反应将需要远超体温的温度才能为分子提供足够的动能以实现成功碰撞。酶通过提供替代的反应途径来降低活化能。它们通过结合底物、使反应物分子以有利方式取向以及稳定过渡态（反应物与产物之间的高能中间状态）来实现这一点。通过降低Eₐ，在任意给定温度下，拥有足够能量反应的底物分子比例大大增加，从而显著提高反应速率。
Reaction rate ∝ 1 ÷ Activation energy (Eₐ)
反应速率 ∝ 1 ÷ 活化能 (Eₐ)
For example, the enzyme catalase decomposes hydrogen peroxide (H₂O₂) into water and oxygen. Without catalase, this reaction proceeds extremely slowly at room temperature. With catalase present, the activation energy drops from approximately 75 kJ mol⁻¹ to around 23 kJ mol⁻¹, increasing the reaction rate by a factor of over one million. This explains why liver tissue, which is rich in catalase, fizzes vigorously when exposed to hydrogen peroxide.
例如，过氧化氢酶将过氧化氢(H₂O₂)分解为水和氧气。如果没有过氧化氢酶，该反应在室温下进行得极其缓慢。有过氧化氢酶存在时，活化能从约75 kJ mol⁻¹降至约23 kJ mol⁻¹，反应速率提高超过一百万倍。这解释了为什么富含过氧化氢酶的肝脏组织接触到过氧化氢时会剧烈冒泡。
4. Factors Affecting Enzyme Activity: Temperature | 影响酶活性的因素：温度
Temperature has a profound effect on enzyme-catalysed reactions. As temperature increases, the kinetic energy of both enzyme and substrate molecules rises, leading to more frequent collisions and a greater likelihood of successful enzyme-substrate complex formation. For most human enzymes, the rate of reaction approximately doubles for every 10°C increase in temperature – a relationship described by the temperature coefficient Q₁₀, which typically has a value of about 2. However, this trend only holds up to an optimum temperature, beyond which the reaction rate declines sharply.
温度对酶催化反应有着深远的影响。随着温度升高，酶和底物分子的动能都增加，导致碰撞更频繁，成功形成酶-底物复合物的可能性更大。对于大多数人体酶来说，温度每升高10°C，反应速率大约翻倍——这一关系由温度系数Q₁₀描述，其典型值为约2。然而，这一趋势仅在达到最适温度之前成立，超过该温度后反应速率急剧下降。
The optimum temperature for most human enzymes is around 37°C – human body temperature. At temperatures above 40-45°C, the weak bonds maintaining the enzyme's tertiary structure – hydrogen bonds, ionic bonds, and hydrophobic interactions – begin to break. The enzyme denatures: its active site loses its specific shape, and the substrate can no longer bind. Denaturation is usually irreversible. At very low temperatures, enzymes are not denatured but become inactive because molecular motion is too slow for effective collisions. Activity resumes when the temperature rises again.
大多数人体酶的最适温度约为37°C——人体体温。在40-45°C以上的温度下，维持酶三级结构的弱键——氢键、离子键和疏水相互作用——开始断裂。酶发生变性：其活性位点失去特定形状，底物无法再结合。变性通常是不可逆的。在极低温度下，酶没有变性，但因分子运动过慢而无法发生有效碰撞而变得不活跃。当温度回升时，活性恢复。
| Temperature Range / 温度范围 | Effect on Enzyme / 对酶的影响 |
|---|---|
| Below 0°C / 0°C 以下 | Activity very low; enzyme intact / 活性极低；酶结构完整 |
| 0-35°C / 0-35°C | Rate increases with temperature / 速率随温度升高而增加 |
| 37°C (optimum) / 37°C（最适） | Maximum rate for human enzymes / 人体酶的最大速率 |
| Above 45°C / 45°C 以上 | Enzyme denatures; rate drops sharply / 酶变性；速率急剧下降 |
5. Factors Affecting Enzyme Activity: pH | 影响酶活性的因素：pH
The pH of the environment affects enzyme activity because hydrogen ions (H⁺) and hydroxide ions (OH⁻) interact with the ionisable side chains of amino acids in the active site. Changes in pH alter the charge distribution within the active site, disrupting the ionic and hydrogen bonds that maintain its precise shape. Each enzyme functions optimally within a narrow pH range. Straying too far from this optimum causes denaturation as the tertiary structure unravels.
环境的pH值影响酶活性，因为氢离子(H⁺)和氢氧根离子(OH⁻)与活性位点中氨基酸的可电离侧链相互作用。pH值的变化改变活性位点内的电荷分布，破坏维持其精确形状的离子键和氢键。每种酶在狭窄的pH范围内才能发挥最佳功能。偏离最适pH值过远会导致变性，因为三级结构会解开。
Different enzymes have evolved to operate at very different pH optima, reflecting the environments in which they function. Pepsin, a digestive enzyme secreted in the stomach, has an optimum pH of approximately 2, matching the highly acidic gastric environment. In contrast, trypsin, a protease secreted into the small intestine, has an optimum pH around 8, suited to the alkaline conditions created by bile and pancreatic secretions. Most intracellular enzymes have optimum pH values close to neutrality (pH 7.0-7.4).
不同的酶进化出在不同pH最适值下运作的能力，反映出它们发挥作用的环境。胃蛋白酶是一种在胃中分泌的消化酶，其最适pH值约为2，与高度酸性的胃环境相匹配。相比之下，胰蛋白酶是一种分泌到小肠的蛋白酶，其最适pH值约为8，适合胆汁和胰腺分泌物创造的碱性条件。大多数细胞内酶的最适pH值接近中性（pH 7.0-7.4）。
6. Substrate Concentration and Enzyme Kinetics | 底物浓度与酶动力学
At a fixed enzyme concentration, increasing the substrate concentration increases the rate of reaction – but only up to a point. When substrate concentration is low, many active sites are unoccupied, and the rate of reaction is directly proportional to substrate concentration. This is the first-order region of the kinetics curve. As more substrate molecules become available, more active sites become occupied, and the rate continues to rise but no longer proportionally. Eventually, at sufficiently high substrate concentrations, all active sites are occupied at any given moment. The enzyme is said to be saturated, and the reaction rate reaches a maximum value called Vₘₐₓ. Further increases in substrate concentration have no effect on the rate.
在酶浓度固定的情况下，增加底物浓度会提高反应速率——但只能提高到一定程度。当底物浓度低时，许多活性位点未被占据，反应速率与底物浓度成正比。这是动力学曲线的一级反应区域。随着底物分子增多，更多活性位点被占据，速率继续上升但不再是成比例地上升。最终，在足够高的底物浓度下，任意给定时刻所有活性位点都被占据。酶达到饱和状态，反应速率达到最大值，称为Vₘₐₓ。进一步增加底物浓度对速率没有影响。
This saturation behaviour is described mathematically by the Michaelis-Menten equation. The Michaelis constant Kₘ is defined as the substrate concentration at which the reaction rate is exactly half of Vₘₐₓ. A low Kₘ value indicates high affinity between enzyme and substrate – the enzyme reaches half-maximal velocity at low substrate concentrations. A high Kₘ indicates lower affinity. Understanding enzyme kinetics is crucial for designing drugs, as many pharmaceuticals function as enzyme inhibitors.
这种饱和行为由米氏方程从数学上加以描述。米氏常数Kₘ定义为反应速率恰好是Vₘₐₓ一半时的底物浓度。Kₘ值低表明酶与底物之间的亲和力高——酶在低底物浓度下即可达到半最大速率。Kₘ值高表明亲和力较低。理解酶动力学对于设计药物至关重要，因为许多药物作为酶抑制剂发挥作用。
7. Enzyme Inhibitors: Competitive and Non-Competitive | 酶抑制剂：竞争性与非竞争性
Enzyme inhibitors are molecules that reduce or abolish enzyme activity. They are classified broadly into two categories: competitive inhibitors and non-competitive inhibitors. Competitive inhibitors have a molecular shape closely resembling that of the normal substrate. They compete with the substrate for the active site, binding reversibly and blocking the substrate from entering. Because competitive inhibition can be overcome by increasing the substrate concentration, the maximum reaction rate Vₘₐₓ remains attainable, but a higher substrate concentration is needed to reach it – meaning Kₘ increases while Vₘₐₓ stays constant.
酶抑制剂是降低或消除酶活性的分子。它们大致分为两类：竞争性抑制剂和非竞争性抑制剂。竞争性抑制剂的分子形状与正常底物非常相似。它们与底物竞争活性位点，可逆地结合并阻止底物进入。由于竞争性抑制可通过增加底物浓度来克服，最大反应速率Vₘₐₓ仍然可以达到，但需要更高的底物浓度才能达到——意味着Kₘ升高而Vₘₐₓ保持不变。
Non-competitive inhibitors bind to a site on the enzyme distinct from the active site – an allosteric site. Their binding changes the overall shape of the enzyme, distorting the active site so that the substrate either cannot bind or cannot be converted to product. Because the inhibitor does not compete for the active site, increasing substrate concentration cannot overcome non-competitive inhibition. Consequently, Vₘₐₓ decreases, while Kₘ remains unchanged. Many metabolic poisons, such as cyanide ions (CN⁻), act as non-competitive inhibitors of critical respiratory enzymes.
非竞争性抑制剂结合到酶上不同于活性位点的位点——一个变构位点。它们的结合改变酶的整体形状，扭曲活性位点，使底物无法结合或无法转化为产物。由于抑制剂不竞争活性位点，增加底物浓度无法克服非竞争性抑制。因此，Vₘₐₓ降低而Kₘ保持不变。许多代谢毒物，如氰根离子(CN⁻)，作为关键呼吸酶的非竞争性抑制剂发挥作用。
| Feature / 特征 | Competitive / 竞争性 | Non-Competitive / 非竞争性 |
|---|---|---|
| Binding site / 结合位点 | Active site / 活性位点 | Allosteric site / 变构位点 |
| Effect on Vₘₐₓ / 对Vₘₐₓ的影响 | Unchanged / 不变 | Decreases / 降低 |
| Effect on Kₘ / 对Kₘ的影响 | Increases / 升高 | Unchanged / 不变 |
| Overcome by substrate / 能否被底物克服 | Yes / 能 | No / 不能 |
8. Digestive Enzymes: A Closer Look | 消化酶：深入探究
The human digestive system produces a suite of enzymes that break down large, insoluble food molecules into small, soluble products that can be absorbed into the bloodstream. Amylase, produced in the salivary glands and pancreas, catalyses the hydrolysis of starch into the disaccharide maltose. Starch is a long polymer of glucose units; amylase cleaves the glycosidic bonds linking these units. The reaction can be tested practically using iodine solution – starch gives a blue-black colour with iodine, but as amylase digests the starch, the colour fades to brown. This provides a straightforward method for investigating enzyme activity in the laboratory.
人类消化系统产生一系列酶，将大的、不溶性的食物分子分解为小的、可溶的产物，使其能被吸收进入血液。淀粉酶由唾液腺和胰腺产生，催化淀粉水解成二糖麦芽糖。淀粉是葡萄糖单元的长链聚合物；淀粉酶切割连接这些单元的糖苷键。该反应可用碘液进行实际测试——淀粉遇碘呈蓝黑色，但随着淀粉酶消化淀粉，颜色褪为棕色。这为在实验室中研究酶活性提供了一种简便方法。
Proteases, including pepsin in the stomach and trypsin in the small intestine, hydrolyse proteins into polypeptides and eventually into individual amino acids. Proteins are composed of long chains of amino acids joined by peptide bonds; proteases target these specific bonds. Lipases, secreted by the pancreas, catalyse the breakdown of lipids (fats and oils) into fatty acids and glycerol. Bile, produced by the liver and stored in the gall bladder, emulsifies fats before lipase action, increasing the surface area available for enzymatic attack. This emulsification is not enzymatic but physical – bile salts break large fat globules into smaller droplets.
蛋白酶，包括胃中的胃蛋白酶和小肠中的胰蛋白酶，将蛋白质水解为多肽，最终分解为单个氨基酸。蛋白质由通过肽键连接的长链氨基酸组成；蛋白酶靶向这些特定的化学键。脂肪酶由胰腺分泌，催化脂质（脂肪和油）分解为脂肪酸和甘油。胆汁由肝脏产生并储存在胆囊中，在脂肪酶作用前将脂肪乳化，增加可供酶攻击的表面积。这种乳化作用不是酶促反应而是物理过程——胆汁盐将大的脂肪球分解为较小的微滴。
9. Enzymes in Industry and Medicine | 酶在工业与医学中的应用
Enzymes have extensive applications beyond living organisms. In the food industry, proteases are used to tenderise meat and clarify fruit juices; amylases convert starch into sugars for sweetener production; and lactase breaks down lactose in milk to produce lactose-free dairy products for individuals with lactose intolerance. In biological washing powders, proteases and lipases digest protein and fat stains on clothing, enabling effective cleaning at lower temperatures – an advantage both for energy saving and for protecting delicate fabrics.
酶在生物体之外有着广泛的应用。在食品工业中，蛋白酶用于嫩化肉类和澄清果汁；淀粉酶将淀粉转化为糖用于甜味剂生产；乳糖酶分解牛奶中的乳糖，为乳糖不耐受人群生产无乳糖乳制品。在生物洗衣粉中，蛋白酶和脂肪酶消化衣物上的蛋白质和脂肪污渍，在较低温度下实现有效清洁——这既有利于节能，也有利于保护精致织物。
In medicine, enzymes serve as diagnostic markers and therapeutic agents. Elevated levels of certain enzymes in the blood can indicate tissue damage: for instance, raised creatine kinase (CK) levels suggest muscle damage or myocardial infarction. Enzyme-linked immunosorbent assays (ELISA) use enzyme-labelled antibodies to detect specific molecules, forming the basis of many diagnostic tests including pregnancy tests and HIV screening. Therapeutic enzymes include streptokinase, used to dissolve blood clots in heart attack patients, and asparaginase, employed in chemotherapy for certain types of leukaemia.
在医学中，酶作为诊断标志物和治疗药物发挥作用。血液中某些酶水平升高可提示组织损伤：例如，肌酸激酶(CK)水平升高表明肌肉损伤或心肌梗死。酶联免疫吸附测定(ELISA)使用酶标记的抗体检测特定分子，构成了许多诊断测试的基础，包括妊娠检测和HIV筛查。治疗用酶包括用于溶解心脏病发作患者血栓的链激酶，以及用于化疗治疗某些类型白血病的门冬酰胺酶。
10. Practical Investigation of Enzyme Activity | 酶活性的实验探究
IGCSE Science courses frequently require students to design and conduct experiments investigating the factors that affect enzyme activity. A classic experiment uses amylase and starch to examine the effect of temperature. Starch solution and amylase are separately equilibrated at a range of temperatures using water baths. They are then mixed, and samples are withdrawn at timed intervals and tested with iodine solution on a spotting tile. The time taken for the blue-black colour to disappear indicates the rate of starch digestion. Plotting rate (1 ÷ time) against temperature yields a characteristic bell-shaped curve peaking at the optimum temperature.
IGCSE 科学课程经常要求学生设计和进行实验，探究影响酶活性的因素。一个经典实验使用淀粉酶和淀粉来检验温度的影响。使用水浴将淀粉溶液和淀粉酶分别在一系列温度下平衡。然后将它们混合，按时间间隔取样，在点滴板上用碘液测试。蓝黑色消失所需的时间表明淀粉消化的速率。将速率（1÷时间）对温度作图，得到一条特征性的钟形曲线，在最适温度处达到峰值。
Key control variables in such experiments include pH (maintained using buffer solutions), enzyme concentration, substrate concentration, and the volumes of all reagents. Only the independent variable (e.g., temperature) should be systematically changed. Reliable results require repeats and calculation of mean values; anomalous results should be identified and excluded. When investigating pH, different buffer solutions – ranging from acidic (low pH) to alkaline (high pH) – must be used, ensuring that the buffer itself does not denature the enzyme or interfere with the detection method.
此类实验中的关键控制变量包括pH值（使用缓冲溶液维持）、酶浓度、底物浓度以及所有试剂的体积。只有自变量（如温度）应当被系统地改变。可靠的结果需要重复实验并计算平均值；应识别并排除异常结果。在研究pH值时，必须使用不同的缓冲溶液——从酸性（低pH）到碱性（高pH）——确保缓冲液本身不会使酶变性或干扰检测方法。
11. Enzyme Cofactors and Coenzymes | 酶的辅助因子与辅酶
Many enzymes require additional non-protein components to function properly. These are broadly termed cofactors. Inorganic cofactors include metal ions such as magnesium (Mg²⁺), which is essential for many enzymes involved in DNA replication and repair; zinc (Zn²⁺), required by carbonic anhydrase; and iron (Fe²⁺ or Fe³⁺), found in cytochromes and catalase. These ions may participate directly in catalysis or stabilise the enzyme-substrate complex.
许多酶需要额外的非蛋白质组分才能正常运作。这些统称为辅助因子。无机辅助因子包括金属离子，如镁离子(Mg²⁺)，它对许多参与DNA复制和修复的酶至关重要；锌离子(Zn²⁺)是碳酸酐酶所需的；铁离子(Fe²⁺或Fe³⁺)存在于细胞色素和过氧化氢酶中。这些离子可能直接参与催化作用或稳定酶-底物复合物。
Organic cofactors, known as coenzymes, are often derived from vitamins. Examples include NAD⁺ (nicotinamide adenine dinucleotide), derived from vitamin B₃ (niacin), which acts as an electron carrier in respiration; FAD (flavin adenine dinucleotide), derived from vitamin B₂ (riboflavin); and coenzyme A, derived from vitamin B₅ (pantothenic acid), which carries acetyl groups in the link reaction and Krebs cycle. Unlike enzymes, coenzymes are chemically changed during the reaction and must be regenerated. The enzyme without its cofactor is called an apoenzyme; with the cofactor bound, it forms the active holoenzyme.
有机辅助因子称为辅酶，通常来源于维生素。例子包括NAD⁺（烟酰胺腺嘌呤二核苷酸），来源于维生素B₃（烟酸），在呼吸作用中作为电子载体；FAD（黄素腺嘌呤二核苷酸），来源于维生素B₂（核黄素）；辅酶A，来源于维生素B₅（泛酸），在连接反应和克雷布斯循环中携带乙酰基。与酶不同，辅酶在反应过程中发生化学变化，必须被再生。没有辅助因子的酶称为脱辅基酶；结合辅助因子后，形成有活性的全酶。
12. Immobilised Enzymes and Biotechnology | 固定化酶与生物技术
In industrial processes, enzymes are often used in an immobilised form. Immobilisation involves attaching enzymes to an inert, insoluble support material such as alginate beads, silica gel, or cellulose fibres. Alternatively, enzymes can be entrapped within a gel matrix or encapsulated in a semi-permeable membrane. Immobilisation offers several significant advantages: the enzyme can be easily recovered from the reaction mixture and reused multiple times, reducing costs; the product is not contaminated with enzyme; and immobilised enzymes often exhibit greater stability against changes in temperature and pH. Continuous-flow reactors packed with immobilised enzymes enable efficient, large-scale production.
在工业过程中，酶常以固定化形式使用。固定化涉及将酶附着在惰性、不溶性载体材料上，如藻酸盐珠子、硅胶或纤维素纤维。或者，酶可以被包埋在凝胶基质中或封装在半透膜内。固定化提供了几个显著优势：酶可以轻松地从反应混合物中回收并重复使用多次，降低成本；产品不会被酶污染；固定化酶通常对温度和pH变化的稳定性更强。填充有固定化酶的连续流反应器能够实现高效的大规模生产。
A prominent example is the use of immobilised lactase to produce lactose-free milk. Milk is passed through a column containing lactase immobilised on alginate beads. Lactose is hydrolysed into glucose and galactose as the milk flows through, yielding a product suitable for lactose-intolerant consumers. Another major application is the production of high-fructose corn syrup (HFCS) using immobilised glucose isomerase, which converts glucose derived from starch into the sweeter fructose. This process supplies the vast quantities of HFCS used in the soft-drink and confectionery industries worldwide.
一个突出的例子是使用固定化乳糖酶生产无乳糖牛奶。牛奶流过一个含有固定在藻酸盐珠子上的乳糖酶的柱子。当牛奶流过时，乳糖被水解为葡萄糖和半乳糖，产生适合乳糖不耐受消费者的产品。另一个重要的应用是使用固定化葡萄糖异构酶生产高果糖玉米糖浆(HFCS)，该酶将从淀粉中提取的葡萄糖转化为更甜的果糖。这一过程为全球软饮料和糖果行业供应着大量的HFCS。
Published by TutorHao | IGCSE Science Revision Series | aleveler.com
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