For faster navigation, this Iframe is preloading the Wikiwand page for 活性位点.

活性位点

维基百科,自由的百科全书

活性位点(英语:Active site),又称激活位置,是指一个酵素中具有催化能力与结合的部位。其结构与化学性质可供底物辨识,并与底物结合。激活位置通常是酵素表面上一个类似口袋的区域,内部含有可与特定底物发生反应的残基

结合

大部分酵素只会有一个活性位点,只对应一种底物。酵素的变性作用,通常是因为高温或者是极端的pH值,造成酵素活性位点形状的改变。

以下有两种酵素结合的假说

酵素锁钥假说

由Emil Fischer提出的,他的假设是说酵素的活性位点和底物可以很完美的结合,当两者结合,底物的修饰就开始了。

诱导契合假说

由Daniel Koshland提出的,它是锁钥理论的延伸,但它主张活性位点和底物不会完美结合,且活性位点是可以形状改变到和底物完美结合的状态;当底物接上后,诱导形状改变,当底物离开后,酵素回到它原本的样子。

化学性质

底物和酵素结合,透过氢键、疏水交互作用或两者都有。活性位点上的残基作为质子或其他底物化学基团的接受者或提供者,进而降低反应激活能,加快反应速率。当酵素和底物间的作用完后,产物在活性位点会相当的不稳定,进而离开酵素。

辅因子

酵素会运用辅因子来帮忙与底物的结合;辅酶也是辅因子的一种,在底物和酵素发生化学反应时,就会离开。例如:金属物质。

抑制剂

抑制剂会阻扰底物和酵素的交互作用,进而降低反应速率。抑制剂有几种不同的种类,分别有可逆和不可逆、竞争和非竞争;竞争型,一种和底物很像的物质,会和底物竞争酵素;非竞争型,一种会结合在非活性位点的物质,会影响底物和酵素的结合率。

例子 和活性位点结合? 降低反应速率?
竞争可逆型 HIV蛋白酶抑制剂
非竞争可逆型 重金属 不会
不可逆型 氰化物

药物的发展

辨认活性位点,在药学上很重要;借由辨认出活性位点,设计出底物(药物),可以阻断它和底物结合;其中一个重要的因子在药物设计,是抑制剂和酵素结合的强度。 例如AIDS

别构结合位

别构结合位顾名思义和活性位点是不同的位置在酵素上,别构修饰通常发生在超过一个次单元的蛋白质,也常常参与代谢反应。

参见

参考文献

  1. ^ Alberts, B (2010). Essential Cell Biology. Garland Science. p. 91.
  2. ^ Campbell, P (2006). Biochemistry Illustrated. Elsevier. pp. 83–85.
  3. ^ Kool ET (1984). "Active site tightness and substrate fit in DNA replication". Annual Review of Biochemistry 71: 191–219. doi:10.1146/annurev.biochem.71.110601.135453.
  4. ^ a b Sullivan SM (2008). "Enzymes with lid-gated active sites must operate by an induced fit mechanism instead of conformational selection". Proceedings of the National Academy of Sciences of the United States of America 105: 13829–13834. doi:10.1073/pnas.0805364105.
  5. ^ a b Schechter I (2005). "Mapping of the active site of proteases in the 1960s and rational design of inhibitors/drugs in the 1990s". Current Protein and Peptide Science 6: 501–512. doi:10.2174/138920305774933286.
  6. ^ a b c DeDecker BS (2000). "Allosteric drugs: thinking outside the active-site box". Chemistry and Biology 7: 103–107. doi:10.1016/S1074-5521(00)00115-0.
  7. ^ Zuercher M (2008). "Structure-Based Drug Design: Exploring the Proper Filling of Apolar Pockets at Enzyme Active Sites". Journal of Organic Chemistry 73: 4345–4361. doi:10.1021/jo800527n.
  8. ^ Powers R (2006). "Comparison of protein active site structures for functional annotation of proteins and drug design". Proteins - Structure, Function and Bioinformatics 65: 124–135. doi:10.1002/prot.21092.
{{bottomLinkPreText}} {{bottomLinkText}}
活性位点
Listen to this article

This browser is not supported by Wikiwand :(
Wikiwand requires a browser with modern capabilities in order to provide you with the best reading experience.
Please download and use one of the following browsers:

This article was just edited, click to reload
This article has been deleted on Wikipedia (Why?)

Back to homepage

Please click Add in the dialog above
Please click Allow in the top-left corner,
then click Install Now in the dialog
Please click Open in the download dialog,
then click Install
Please click the "Downloads" icon in the Safari toolbar, open the first download in the list,
then click Install
{{::$root.activation.text}}

Install Wikiwand

Install on Chrome Install on Firefox
Don't forget to rate us

Tell your friends about Wikiwand!

Gmail Facebook Twitter Link

Enjoying Wikiwand?

Tell your friends and spread the love:
Share on Gmail Share on Facebook Share on Twitter Share on Buffer

Our magic isn't perfect

You can help our automatic cover photo selection by reporting an unsuitable photo.

This photo is visually disturbing This photo is not a good choice

Thank you for helping!


Your input will affect cover photo selection, along with input from other users.