2c53: Difference between revisions

Uracil-DNA glycosylase (UNG) is the key enzyme responsible for initiation, of base excision repair. We have used both kinetic and binding assays for, comparative analysis of UNG enzymes from humans and herpes simplex virus, type 1 (HSV-1). Steady-state fluorescence assays showed that hUNG has a, much higher specificity constant (k(cat)/K(m)) compared with the viral, enzyme due to a lower K(m). The binding of UNG to DNA was also studied, using a catalytically inactive mutant of UNG and non-cleavable substrate, analogs (2'-deoxypseudouridine and 2'-alpha-fluoro-2'-deoxyuridine)., Equilibrium DNA binding revealed that both human and HSV-1 UNG enzymes, bind to abasic DNA and both substrate analogs more weakly than to, uracil-containing DNA. Structure determination of HSV-1 D88N/H210N UNG in, complex with uracil revealed detailed information on substrate binding., Together, these results suggest that a significant proportion of the, binding energy is provided by specific interactions with the target, uracil. The kinetic parameters for human UNG indicate that it is likely to, have activity against both U.A and U.G mismatches in vivo. Weak binding to, abasic DNA also suggests that UNG activity is unlikely to be coupled to, the subsequent common steps of base excision repair.

2C53 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Human_herpesvirus_4 Human herpesvirus 4] with DUR and GOL as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Uridine_nucleosidase Uridine nucleosidase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.2.2.3 3.2.2.3] Structure known Active Site: AC1. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=2C53 OCA].  

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