Wikipedia.
A polymerase (EC 2.7.7.6/7/19/48/49) is an enzyme whose central function is associated with polymers of nucleic acids such as RNA and DNA. The primary function of a polymerase is the polymerization of new DNA or RNA against an existing DNA or RNA template in the processes of replication and transcription. In association with a cluster of other enzymes and proteins, they take nucleotides from solvent, and catalyse the synthesis of a polynucleotide sequence against a nucleotide template strand using base-pairing interactions.
It is an accident of history that the enzymes responsible for the catalytic production of other biopolymers are not also referred to as polymerases.
One particular polymerase, from the thermophilic bacterium, Thermus aquaticus (Taq) (PDB 1BGX, EC 2.7.7.7) is of vital commercial importance due to its use in the polymerase chain reaction, a widely used technique of molecular biology.
Other well-known polymerases include:
* Terminal Deoxynucleotidyl Transferase (TDT), which lends diversity to antibody heavy chains
* Reverse Transcriptase, an enzyme used by RNA retroviruses like HIV, which is used to create a complementary strand to the preexisting strand of viral RNA before it can be integrated into the DNA of the host cell. It is also a major target for antiviral drugs.