1qzq
From Proteopedia
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human Tyrosyl DNA phosphodiesterase
Contents |
Overview
Tyrosyl-DNA phosphodiesterase I (Tdp1) is involved in the repair of DNA, lesions created by topoisomerase I in vivo. Tdp1 is a member of the, phospholipase D (PLD) superfamily of enzymes and hydrolyzes, 3'-phosphotyrosyl bonds to generate 3'-phosphate DNA and free tyrosine in, vitro. Here, we use synthetic 3'-(4-nitro)phenyl, 3'-(4-methyl)phenyl, and, 3'-tyrosine phosphate oligonucleotides to study human Tdp1. Kinetic, analysis of human Tdp1 (hTdp1) shows that the enzyme has nanomolar, affinity for all three substrates and the overall in vitro reaction is, diffusion-limited. Analysis of active-site mutants using these modified, substrates demonstrates that hTdp1 uses an acid/base catalytic mechanism., The results show that histidine 493 serves as the general acid during the, initial transesterification, in agreement with hypotheses based on, previous crystal structure models. The results also argue that lysine 495, and asparagine 516 participate in the general acid reaction, and the, analysis of crystal structures suggests that these residues may function, in a proton relay. Together with previous crystal structure data, the new, functional data provide a mechanistic understanding of the conserved, histidine, lysine and asparagine residues found among all PLD family, members.
Disease
Known disease associated with this structure: Spinocerebellar ataxia, autosomal recessive with axonal neuropathy OMIM:[607198]
About this Structure
1QZQ is a Single protein structure of sequence from Homo sapiens. Full crystallographic information is available from OCA.
Reference
Analysis of human tyrosyl-DNA phosphodiesterase I catalytic residues., Raymond AC, Rideout MC, Staker B, Hjerrild K, Burgin AB Jr, J Mol Biol. 2004 May 14;338(5):895-906. PMID:15111055
Page seeded by OCA on Mon Nov 12 18:57:54 2007
