site-specific endodeoxyribonuclease activity, specific for altered base

Definition

Target type: molecularfunction

Catalysis of the hydrolysis of ester linkages at specific sites within a deoxyribonucleic acid molecule by creating internal breaks. [GOC:jl]

Site-specific endodeoxyribonuclease activity, specific for altered base, refers to the enzymatic function of cleaving DNA at specific sites where the base sequence has been altered. This alteration can involve a variety of modifications, including:

* **Base modifications:** This includes methylation, deamination, oxidation, and other chemical modifications that change the structure of a base.
* **Base mismatches:** These are errors in DNA replication where the wrong base is incorporated opposite a template base.
* **DNA lesions:** These are damages to DNA bases caused by exposure to radiation, chemicals, or reactive oxygen species.

The enzymes that exhibit this activity are often called **restriction endonucleases** or **DNA glycosylases**. They recognize the altered base or mismatch within a specific DNA sequence and cleave the phosphodiester backbone of the DNA molecule, creating a double-strand break. This cleavage can be either **5'-3'** or **3'-5'**, depending on the specific enzyme.

The molecular mechanism of site-specific endodeoxyribonuclease activity, specific for altered base, involves several steps:

1. **Recognition of the altered base:** The enzyme binds to the DNA molecule and specifically recognizes the altered base or mismatch.
2. **Cleavage of the phosphodiester bond:** The enzyme cleaves the DNA backbone at a specific site near the altered base.
3. **Removal of the altered base (in some cases):** Some enzymes, like DNA glycosylases, remove the altered base in addition to cleaving the DNA.

This activity plays a crucial role in various cellular processes, including:

* **DNA repair:** The enzymes can repair damaged DNA by removing the altered base and replacing it with the correct one.
* **Immune defense:** Some restriction endonucleases are used by bacteria to defend against invading viruses.
* **Genetic engineering:** Restriction endonucleases are widely used in molecular biology for manipulating DNA.

In summary, site-specific endodeoxyribonuclease activity, specific for altered base, is a crucial enzymatic function that recognizes and cleaves DNA at specific sites where the base sequence has been altered. This activity plays a vital role in DNA repair, immune defense, and genetic engineering.'
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Proteins (1)

Compounds (17)