DNA polymerase I.
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The DNA polymerase I is an enzyme which is the synthesis of DNA from deoxyribonucleotides catalyzed on a DNA template. DNA polymerase I plays a role in prokaryotic DNA replication . The most important feature is its 5'-3 'exonuclease activity. In addition to DNA polymerase I, two other DNA polymerases are also known in prokaryotes.
function
DNA polymerase I is a slower polymerase than DNA polymerase III , therefore it does not serve the main synthesis of the DNA strand during replication. It has low processivity . It serves to degrade the primer through the 5'-3 ' exonuclease activity. It also fills the resulting gaps in the strand again with dNTPs . The polymerase works from 5 '→ 3' direction, in that a nucleophilic attack of the terminal 3'- OH of the DNA strand takes place on the 5'- phosphate of the dNTP, with pyrophosphate being split off. The DNA polymerase needs a free 3'-hydroxy group in order to attach nucleotides to it and uses the end of the previously synthesized Okazaki fragment for this . It is also possible for DNA polymerase I to proofread 3 '→ 5' and to replace incorrectly incorporated nucleotides via the exonuclease activity.
construction
The DNA polymerase I consists of a single strand with about 1000 base pairs. The molecular mass is 109 kDa. In order to carry out its tasks, it has several domains: for synthesis, proofreading and removal of nucleotides.
discovery
The DNA polymerase I (Pol I) was founded in 1955 by Arthur Kornberg isolated and was the first polymerase at all, which was discovered. In 1959 Kornberg received the Nobel Prize for this .
See also
Individual evidence
- ↑ a b DNA Polymerase I - Worthington Enzyme Manual. Retrieved February 19, 2020 .
- ↑ Nicole Kresge, Robert D. Simoni, Robert L. Hill: Arthur Kornberg's discovery of DNA polymerase I . In: Journal of Biological Chemistry . tape 280 , no. 49 , December 9, 2005, ISSN 0021-9258 , p. e46 – e46 ( jbc.org [accessed February 19, 2020]).