DNA Polymerase: It is a type of enzyme that is responsible for forming new copies of DNA, in the form of nucleic acid molecules. Nucleic acids are polymers, which are large molecules made up of smaller, repeating units that are chemically connected to one another. DNA is composed of repeating units called nucelotides or nucleotide bases.

DNA polymerase is responsible for the process of DNA replication, during which a double-stranded DNA molecule is copied into two identical DNA molecules. Scientists have taken advantage of the power of DNA polymerase molecules to copy DNA molecules in test tubes via polymerase chain reaction, also known as PCR.

Functions of DNA polymerase

• Replication: The main function of the DNA polymerase is to synthesize DNA by the process of replication.
• Repair: The replication process is a humongous task and it is important to maintain the integrity of the genome. 
• Proofreading: DNA replication is not perfect and there occurs an error after every 10⁴ to 10⁵ nucleotides added. Removing the incorrect nucleotide sequence or mismatched nucleotides from the newly synthesised strand is very important for the functionality of proteins, which can even lead to cancer.

Structure of DNA polymerase

• The DNA polymerases generally have a conserved structure, and therefore, defining its vital role in the cell function which can not be replaced.
• DNA polymerases are made up of subdomains resembling an open right hand as palm, fingers, and thumb.
• The palm contains the catalytic essential amino acids in its active sites.
• The fingers play a major role in nucleotide recognition and binding.
• The thumb is for binding of the DNA substrate
• There is a domain found between the finger and the thumb known as a pocket, which is made up of two regions i.e the insertion site and the post-insertion site.
• The incoming nucleotides bind to the insertion site while the new base pair bind in the post-insertion site.
• Other subdomains along with these domains are specific for each family, and each has essential functions in DNA replication.
• However, these subdomains are different for each polymerase.

Mechanism of DNA polymerase

The mechanism of DNA polymerase is referred to as a two metal ion mechanism i.e two metal ions act as active sites for stabilizing the transmission of replication. The first metal ion acts by activating the hydroxyl group which attacks the phosphate group of the dNTP and the second metal ion stabilizes the negative charges and builds on the left oxygen and chelating phosphate groups.

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By Team Learning Mantras