List of 17 Enzymes with their function that are used in recombinant DNA technology /Genetic Engineering
1. Alkaline phosphatase: This enzyme helps to remove the phosphate groups from 5’-ends of double and single standard DNA and RNA. It also helps prevent re-circularization during cloning and dephosphorylate DNA before Kinase labeling protocols.
2. Terminal Transferase: Enzyme very useful in homopolymer tailing. It helps to add nucleotides to the 3’ends of DNA or RNA. This enzyme is used as a template for a primer in subsequent PCR.
3. Bal 3I nuclease: In DNA technology this enzyme is used to degrade both 3’ and 5’ termini of duplex DNA without generating any internal scissions. In short, this enzyme is used for the progressive shortening of DNA.
4. S1nuclease: It is an endonuclease enzyme that helps to degrade single-standard DNA and RNA but can’t degrade double-standard DNA or RNA-DNA hybrids.
5. DNA Ligase: In DNA replication, the DNA ligase enzyme helps to join DNA molecules by forming phosphodiester linkages between DNA segments that help to synthesize DNA to form a seamless strand. This enzyme is also used in DNA cloning for the same process.
6. Taq DNA Polymerase: Taq DNA polymerase enzyme used in PCR i.e. Polymerase Chain Reaction to recruit new nucleotides to single strands of DNA in the denaturation step that is taking place in a PCR reaction that helps to complete DNA replication to make DNA copies.
7. DNA polymerase I: This enzyme is coded by the pol1 gene that helps in prokaryotic DNA replication. DNA polymerase helps to synthesize the DNA complementary to a DNA template by removing RNA primer during the processing of DNA after replication. It also fills the gap.
8. RNase H: RNase H is known as the Ribonuclease H enzyme. This is an endoribonuclease enzyme that helps to cleave and digest the RNA strand of RNA-DNA heteroduplex (RNA-DNA hybrids). The purpose of the RNase H enzyme is to form double-strand cDNA.
9. DNase I: It is a type of recombinant endonuclease enzyme that helps to produce single-standard nicks in DNA.
10. RNase A: RNase A is a Ribonuclease enzyme that helps in cleavage and digests RNA (and not DNA). This enzyme unwinds the RNA helix by complexing with single-standard RNA. The major role of this enzyme is in RNA metabolism and regulation of gene expression.
11. Exonuclease III: This enzyme has exonucleolytic activity. It helps to remove nucleotides from the 3’-end of DNA.
12. Reverse transcriptase: It helps to synthesize DNA from RNA to produce complementary DNA (cDNA) libraries from variously expressed mRNAs. This enzyme is also used in RT PCR.
13. Polynucleotide Kinase: PNK (Polynucleotide kinase) that helps to transfer a phosphate group from ATP (Adenosine triphosphate) to 5’OH ends of DNA or RNA. Sometimes they show phosphate activities.
14. Restriction Enzymes: The restriction enzyme cuts double-standard DNA with a specific recognition site. It is a type of protein that is isolated from bacteria.
15. Type I Restriction endonuclease: This enzyme requires ATP to cut DNA about 1000bp away from its restriction site. It shows both methylation and endonuclease activity.
16. Type II Restriction endonuclease: This enzyme doesn’t require ATP to cut DNA. It cuts DNA at the restriction site.
17. Type III Restriction endonuclease: This enzyme requires ATP to cut DNA about 25bp away from the restriction site.
Originally published at https://www.kiranjeetkaurbiotechnologist.com on July 3, 2024.
