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  • General

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  • 酶函数

    What will you learn
    ::你会学到什么

    • How do work
      ::如何工作
    • What is the role of the active site of an enzyme
      ::一种酶的有效网址的作用是什么?
    • Factors that affect enzyme activity
      ::影响酶活动的因素

    A scattered collection of jigsaw puzzle pieces, illustrating the complexity of enzyme interactions.

    Do cells have one enzyme with lots of functions, or many enzymes, each with just one function?
    ::细胞中是否有一种酶, 具有许多功能, 或许多酶, 每个都只有一个函数?

    Enzymes. Vital   necessary for life. So how do enzymes work? How do they catalyze just one specific ? In a puzzle, only two pieces will fit together properly. Understanding that is one of the main steps in understanding how enzymes work.
    ::酶。 生命所必需的生命。 那么酶是如何起作用的呢? 它们是如何催化一个特定的呢? 在谜题中, 只有两块可以适当组合。 理解这是理解酶是如何起作用的主要步骤之一。

    Enzyme Function
    ::酶函数

    How do enzymes speed up biochemical reactions so dramatically? Like all catalysts , enzymes work by lowering the activation energy of chemical reactions . Activation energy is the energy needed to start a chemical reaction. This is illustrated in the  Figure . The biochemical reaction shown in the figure requires about three times as much activation energy without the enzyme as it does with the enzyme.
    ::如何使酶加速如此剧烈的生化反应?像所有催化剂一样,酶通过降低化学反应的激活能量而产生作用。激活能量是开始化学反应所需的能量。图中说明了这一点。图中显示的生化反应需要大约三倍的活化能量,而没有酶则需要三倍的活化能量。

    Graph comparing activation energy with and without an enzyme during a biochemical reaction.
    The enzyme speeds up the reaction by lowering the activation energy needed for the reaction to start. Compare the activation energy with and without the enzyme.

    Enzymes generally lower activation energy by reducing the energy needed for reactants to come together and react. For example:
    ::通过减少反应剂聚集并作出反应所需的能量,酶一般会降低活性能。

    • Enzymes bring reactants together so they don’t have to expend energy moving about until they collide at random. Enzymes bind both reactant molecules (called the substrate ), tightly and specifically, at a site on the enzyme molecule called the active site .
      ::酶把反应器聚集在一起,这样它们就不必在随机碰撞之前花费能量。 酶将两个反应分子(称为基质)紧紧和具体地放在酶分子上的一个网站“活性点 ” , 紧紧和具体地捆绑在一起。
    • By binding reactants at the active site, enzymes also position reactants correctly, so they do not have to overcome intermolecular forces that would otherwise push them apart. This allows the molecules to interact with less energy.
      ::通过在活跃点的绑定反应器,酶还正确地定位反应器,因此它们不必克服会将他们分开的分子间联力量。这使得分子能够以较少的能量进行互动。
    • Enzymes may also allow reactions to occur by different pathways that have lower activation energy.
      ::酶还可能允许不同途径发生反应,而不同途径的活性能较低。

     

     

     

    DID YOU KNOW?
    Enzymes are crucial to metabolic reactions. Almost all metabolic reactions are catalyzed by enzymes and it is estimated to be around 75,000 different enzymes in the .  
     

    The active site is specific for the reactants of the biochemical reaction the enzyme catalyzes. Similar to puzzle pieces fitting together, the active site can only bind certain substrates.
    ::活动场地是专门为生化反应反应反应反应反应者而设的,即酶催化器。与拼图拼凑在一起的拼图相似,活动场地只能捆绑某些基质。

    The activities of enzymes also depend on the surrounding conditions such as the temperature and the pH. For example, some enzymes work best at acidic pHs, while others work best in neutral environments.
    ::酶的活动还取决于周围的温度和pH值等条件。 例如,一些酶在酸性pH值方面最有效,而另一些则在中性环境中最有效。

    • Digestive enzymes secreted in the acidic environment (low pH) of the stomach help break down proteins into smaller molecules. The main digestive enzyme in the stomach is pepsin , which works best at a pH of about 1.5. These enzymes would not work optimally at other pHs. Trypsin is another enzyme in the , which breaks protein chains in food into smaller parts. Trypsin works in the , which is not an acidic environment. Trypsin's optimum pH is about 8.  
      ::胃酸环境(低pH)中隐蔽的消化酶,有助于将蛋白分解成小分子。胃中主要的消化酶是pepsin,在pH值约为1.5时效果最好。这些酶在其他pH值中不会产生最佳效果。 Tripsin是胃中的另一个酶,它把食物中的蛋白链分解成小部分。Trypsin在不是酸性环境的情况下工作。 Tripsin的最佳pH值约为8。 Trypsin的最佳pH值约为8。
    • Biochemical reactions are optimal at physiological temperatures. For example, most biochemical reactions work best at the normal body temperature of 98.6˚F. Many enzymes lose function at lower and higher temperatures compared to their optimum temperature . At higher temperatures, an enzyme’s shape deteriorates, also known as denaturing . Only when the temperature comes back to normal does the enzyme regain its shape and normal activity.
      ::生物化学反应在生理温度下是最佳的。 比如,大多数生物化学反应在正常体温98.6 °F 。 许多酶在低于最佳温度的低温和高温下失去功能。 在较高温度下,酶的形状会恶化,也被称为衰减。 只有当温度恢复正常时,酶才会恢复其形状和正常活动。

    Explore the effect of pH on the activity of the pepsin enzyme
    ::探索pH对pepsin酶活动的影响

    Summary
    ::摘要

    • Enzymes work by lowering the activation energy needed to start biochemical reactions.
      ::通过降低启动生化反应所需的活性能量来产生酶。
    • The activities of enzymes depend on the temperature and the pH of the surroundings.
      ::酶的活动取决于周围的温度和pH值。

    Review
    ::回顾

    1. How do enzymes speed up biochemical reactions?
      ::酶如何加速生化反应?
    2. Where is the active site located? Explain the role of the active site?
      ::活动地点在哪里? 解释活动地点的作用吗 ?
    3. Complete this sentence: The activities of enzymes depends on the __________ and the __________ of the surroundings.
      ::完整本句:酶的活动取决于周围环境的 和 。
    4. Distinguish between the conditions needed for the proper functioning of pepsin and trypsin.
      ::区分pepsin和trypsin的正常运作所需的条件。