polimerase

Polimerase, or polymerase in English, is an enzyme that catalyzes the formation of polymers by linking activated nucleotide precursors. In biology, different polymerases synthesize nucleic acids: DNA polymerases build DNA, while RNA polymerases synthesize RNA. A reverse transcriptase can synthesize DNA from an RNA template.

DNA polymerases are essential for genome replication and repair. In bacteria, DNA Pol I, II, and III participate in replication and repair; in eukaryotes, multiple DNA polymerases operate, including DNA polymerase alpha, delta, and epsilon that handle initiation and elongation of chromosomal DNA, and polymerases such as gamma in mitochondria and zeta in translesion synthesis. Telomerase is a specialized reverse transcriptase that extends telomeres using an RNA template.

RNA polymerases transcribe genetic information from DNA into RNA. In bacteria, the RNA polymerase holoenzyme recognizes promoters with a sigma factor; in eukaryotes, RNA polymerase II transcribes mRNA, while I and III transcribe rRNA and tRNA. Transcription proceeds in the 5' to 3' direction, using ribonucleoside triphosphates as substrates.

Biochemical properties include dependence on divalent metal ions such as Mg2+ or Mn2+. Many DNA polymerases have proofreading 3' to 5' exonuclease activity, improving fidelity; others lacking this activity have higher error rates. In laboratory research and clinical diagnostics, thermostable DNA polymerases enable polymerase chain reaction (PCR); high-fidelity enzymes provide greater accuracy. Polimerases thus play central roles in genetics, molecular biology, and biotechnology.