Nukleotidiltransferaza

Nukleotidiltransferaze su grupa transferaznih enzima koji sadrže fosfor, npr. supstituenti nukleotidilnih kiselina ili jednostavno nukleozid-monofosfat. Opća reakcija prijenosa nukleozidnog monofosfatnog dijela iz A u B može se zapisati kao:

A-P-N + B

\rightleftharpoons

A + B-P-N

Naprimjer, u slučaju polimeraza, A je pirofosfat, a B je polinukleotid u nastajanju. Oni su klasificirani pod [[Enzim Commw9iudn owiddmlsi; ja \ l- grupe

Adenililtransferaza, koja prenosi adenilil - grupe
Gvanililtransferaza, koja prenosi gvanilil - grupe
Cititidililtransferaza, koja prenosi citidilil - grupe
Timidililtransferaza, koja prenosi timidilil - grupe

Uloga u metabolizmu

Mnogi metabolički enzimi su modificirani nukleotidiltransferazama. Veznje AMP (adeniliranje) ili UMP (uridililiranje) može aktivirati ili deaktivirati enzim ili promijeniti njegovu specifičnost (vidi sliku). Ove modifikacije mogu dovesti do zamršenih regulatornih mreža koje mogu fino podesiti enzimske aktivnosti, tako da nastaju samo potrebni spojevi (ovdje: glutamin).

Uloga u mehanizmima za popravak DNK

Nukleotidil-transferaza je komponenta puta reparacije jednostrukog nukleotida (popravak bazne ekscizije). Ovaj mehanizam popravljanja započinje kada DNK-glikozilaza prepozna jedan nukleotid kao pogrešno podudarni ili je na neki način mutiran (UV svjetlost, hemijski mutagen, itd.) i uklonjen. Kasnije se nukleotidil-transferaza koristi za popunjavanje praznine ispravnom bazom, koristeći šablonski lanac kao referencu.^[2]

Reference

^ Voet D, Voet JG, Pratt CW (2008). Fundamentals of Biochemistry (3rd ed.). John Wiley & Sons, pp. 767
^ Yuan Liu; Rajendra Prasad; William A. Beard; Padmini S. Kedar; Esther W. Hou; David D. Shock; Samuel H. Wilson (4. 5. 2007). "Coordination of Steps in Single-nucleotide Base Excision Repair Mediated by Apurinic/Apyrimidinic Endonuclease 1 and DNA Polymerase β". Journal of Biological Chemistry. 282 (18): 13532–13541. doi:10.1074/jbc.M611295200. PMC 2366199. PMID 17355977. The enzymes and accessory factors involved in the BER subpathways in mammalian cells have received considerable attention. As summarized above, five distinct enzymatic reaction are involved during SN-BER. These are 1) removal of a modified base by a lesion-specific monofunctional DNA N-glycosylase, 2) 5'-incision of the abasic site by a hydrolytic strand incision enzyme, 3) DNA synthesis by a nucleotidyltransferase, 4) removal of the 5'-dRP group by a'-elimination reaction, and 5) nick sealing by DNA ligase (36, 37)

Vanjski linkovi

Nucleotidyltransferases na US National Library of Medicine Medical Subject Headings (MeSH)

Portal Biologija

[:0-1] Voet D, Voet JG, Pratt CW (2008). Fundamentals of Biochemistry (3rd ed.). John Wiley & Sons, pp. 767

[2] Yuan Liu; Rajendra Prasad; William A. Beard; Padmini S. Kedar; Esther W. Hou; David D. Shock; Samuel H. Wilson (4. 5. 2007). "Coordination of Steps in Single-nucleotide Base Excision Repair Mediated by Apurinic/Apyrimidinic Endonuclease 1 and DNA Polymerase β". Journal of Biological Chemistry. 282 (18): 13532–13541. doi:10.1074/jbc.M611295200. PMC 2366199. PMID 17355977. The enzymes and accessory factors involved in the BER subpathways in mammalian cells have received considerable attention. As summarized above, five distinct enzymatic reaction are involved during SN-BER. These are 1) removal of a modified base by a lesion-specific monofunctional DNA N-glycosylase, 2) 5'-incision of the abasic site by a hydrolytic strand incision enzyme, 3) DNA synthesis by a nucleotidyltransferase, 4) removal of the 5'-dRP group by a'-elimination reaction, and 5) nick sealing by DNA ligase (36, 37)

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