Development of a novel assay for human tyrosyl DNA phosphodiesterase 2.
Anal Biochem
; 416(1): 112-6, 2011 Sep 01.
Article
en En
| MEDLINE
| ID: mdl-21620793
ABSTRACT
Tyrosyl DNA phosphodiesterase 2 (TDP2), a newly discovered enzyme that cleaves 5'-phosphotyrosyl bonds, is a potential target for chemotherapy. TDP2 possesses both 3'- and 5'-tyrosyl-DNA phosphodiesterase activity, which is generally measured in a gel-based assay using 3'- and 5'-phosphotyrosyl linkage at the 3' and 5' ends of an oligonucleotide. To understand the enzymatic mechanism of this novel enzyme, the gel-based assay is useful, but this technique is cumbersome for TDP2 inhibitor screening. For this reason, we have designed a novel assay using p-nitrophenyl-thymidine-5'-phosphate (T5PNP) as a substrate. This assay can be used in continuous colorimetric assays in a 96-well format. We compared the salt and pH effect on product formation with the colorimetric and gel-based assays and showed that they behave similarly. Steady-state kinetic studies showed that the 5' activity of TDP2 is 1000-fold more efficient than T5PNP. Tyrosyl DNA phosphodiesterase 1 (TDP1) and human AP-endonuclease 1 (APE1) could not hydrolyze T5PNP. Sodium orthovanadate, a known inhibitor of TDP2, inhibits product formation from T5PNP by TDP2 (IC(50)=40 mM). Our results suggest that this novel assay system with this new TDP2 substrate can be used for inhibitor screening in a high-throughput manner.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Factores de Transcripción
/
Proteínas Nucleares
/
Colorimetría
Límite:
Humans
Idioma:
En
Revista:
Anal Biochem
Año:
2011
Tipo del documento:
Article
País de afiliación:
Estados Unidos