Klenow和T4 DNA聚合酶之间的差异

Thekey differencebetween Klenow and T4 DNA polymerase is thatKlenow fragment is a large fragment ofE. coliDNA polymerase 1而T4 DNA聚合酶是DNA聚合酶1的1噬菌体T4。

DNA聚合酶是通过将脱氧核糖核苷酸添加到预先存在的底漆的3'-OH端来催化DNA的酶。有不同类型的DNA聚合酶。分子生物学中使用的大多数DNA聚合酶是原核DNA聚合酶。Klenow片段和T4 DNA聚合酶是具有核酸起源的两种类型的DNA聚合酶。klenow碎片是从乳沟产生的大片段E.coliDNA聚合酶1分成两个细菌蛋白酶枯草蛋白分成两个片段。T4 DNA聚合酶是噬菌体T4的DNA聚合酶1。Klenow和T4 DNA聚合酶均具有5'→3'聚合酶和3'→5'exonucleaseactivity. They both lack 5′→3′ exonuclease activity, making them more suitable for many applications in molecular biology.

内容

1.Overview and Key Difference
2.What is Klenow
3.What is T4 DNA Polymerase
4.Similarities Between Klenow and T4 DNA Polymerase
5.Side by Side Comparison – Klenow vs T4 DNA Polymerase in Tabular Form
6.概括

What is Klenow?

Klenow fragment is a DNA polymerase that is useful in molecular biology. WhenE. coliDNA polymerase 1 undergoes proteolytic digestion by bacterial protease, subtilisin, it results in two fragments: one is a large fragment, and the other one is a small fragment. Klenow fragment is the large fragment which is 68 kDa in size. Klenow fragment has 5′→3′ polymerase and 3′→5′ exonuclease (proofreading) activities of DNA Pol I. The 3′→5′ exonuclease activity of the Klenow fragment facilitates the removal of incorrectly added bases as polymerization progresses. Klenow fragment does not contain 5′→3′ exonuclease activity, which is shown by full-length or intactE. coliDNA聚合酶1.仅需单独使用聚合活性时，这是有利的。Klenow片段用于填充5'突出，探针的合成，测序DNA，双链DNA的合成，cDNA第二链的合成和定点诱变。

In certain applications, the 3′→5′ exonuclease activity of the Klenow fragment also becomes undesirable. It can be removed by introducing a mutation to the gene that codes for Klenow fragment. The resulting Klenow fragment is known as exo-Klenow fragment. Therefore, exo-Klenow fragment has only the 5′→3′ polymerase activity ofE. coli聚合酶1。

什么是T4 DNA聚合酶？

T4 DNA polymerase is a DNA polymerase that catalyzes the synthesis of DNA. It is a protein coded by Bacteriophage T4. Structurally, T4 DNA polymerase is an 898 amino acid residue protein (molecular weight of 103.6 kDa). It requires a template and a primer to catalyze the synthesis.

与Klenow片段相似，T4 DNA聚合酶具有5'→3'聚合酶和3'→5'外核酸酶活性。此外，它也缺乏5'→3'外切核酸酶活性。T4 DNA聚合酶可用于填充DNA片段的5'缩端。它通常也用于双链DNA的5'端或3'端标签。T4 DNA聚合酶经常用于钝化克隆。T4 DNA聚合酶的3'→5'外切核酸酶（校对）活性比Klenow片段强（超过200倍）。最重要的是，T4 DNA聚合酶具有较高的加工性（每秒400个核苷酸）。

What are the Similarities Between Klenow and T4 DNA Polymerase?

• Klenow and T4 DNA polymerase are two prokaryotic polymerases.
• 两种聚合酶均具有5'→3'聚合酶和3'→5'外核酸酶活性。
• They do not exhibit 5′→3′ exonuclease activity.
• 两种酶都需要模板和底漆来催化DNA的合成。
• These enzymes can be heat inactivated at 75⁰

What is the Difference Between Klenow and T4 DNA Polymerase?

The key difference between Klenow and T4 DNA polymerase is the origin of each enzyme. Klenow fragment is originated from a bacterium while T4 DNA polymerase is originated from a bacteriophage which is a virus. T4 DNA polymerase has a high processivity than Klenow fragment. Moreover, T4 DNA polymerase has a strong proofreading activity than the Klenow fragment. Thus, this is another difference between Klenow and T4 DNA polymerase.

以下信息图列出了表格形式的Klenow和T4 DNA聚合酶之间的更多差异。

摘要 - Klenow vs T4 DNA聚合酶

Klenow fragment is a large fragment of E. coli DNA polymerase 1. It has only 5′→3′ polymerase and 3′→5′ exonuclease activities. It lacks 5′→3′ exonuclease activity of intact E. coli DNA pol 1. Therefore, Klenow fragment is a bacterial polymerase. On the other hand, T4 DNA polymerase is a polymerase coded by the bacteriophage T4. Similar to the Klenow fragment, it contains both 5′→3′ polymerase and 3′→5′ exonuclease activities, and it lacks 5′→3′ exonuclease activity. However, T4 DNA polymerase has high processivity and high proofreading activity than the Klenow fragment. So, this is the key difference between Klenow and T4 DNA polymerase.

Reference:

1.“ DNA聚合酶，T4。”。DNA聚合酶，T4 - 沃辛顿酶手册，Available here.
2.Rittié，Laure和Bernard Perbal。“分子生物学中使用的酶：有用的指南。”细胞通信与信号杂志，荷兰施普林格，2008年6月，Available here.

Image Courtesy:

1. “PolymeraseDomains” – Protein Data Bank (Public Domain) viaCommons Wikimedia

2. “T4-DNA-Polymerase” By ChemPro – J. Wang, P. Yu, T. C. Lin, W. H. Konigsberg, T. A. Steitz (1996). “Crystal structures of an NH2-terminal fragment of T4 DNA polymerase and its complexes with single-stranded DNA and with divalent metal ions” Biochemistry 35: 8110–8119. DOI:10.1021/bi960178r. (CC0) viaCommons Wikimedia