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</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=PO4:PHOSPHATE+ION'>PO4</scene>, <scene name='pdbligand=SO4:SULFATE+ION'>SO4</scene></td></tr>

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== Publication Abstract from PubMed ==

Glycinamide ribonucleotide transformylase (GAR Tfase) is a folate-dependent enzyme in the de novo purine biosynthesis pathway, which has long been considered a potential target for development of anti-neoplastic therapeutics. Here we report the biological and X-ray crystallographic evaluations of both independent C10 diastereomers, 10S- and 10R-methylthio-DDACTHF, bound to human GAR Tfase, including the highest-resolution apo GAR Tfase structure to date (1.52 A). Both diastereomers are potent inhibitors (Ki = 210 nM for 10R, and Ki = 180 nM for 10S) of GAR Tfase and exhibit effective inhibition of human leukemia cell growth (IC50 = 80 and 50 nM, respectively). Their inhibitory activity was surprisingly high, and these lipophilic C10-substituted analogues show distinct advantages over their hydrophilic counterparts, most strikingly in retaining potency in mutant human leukemia cell lines that lack reduced folate carrier protein activity (IC50 = 70 and 60 nM, respectively). Structural characterization reveals a new binding mode for these diastereoisomers, in which the lipophilic thiomethyl groups penetrate deeper into a hydrophobic pocket within the folate-binding site. In silico docking simulations of three other sulfur-containing folate analogues also indicate that this hydrophobic cleft represents a favorable region for binding lipophilic substituents. Overall, these results suggest sulfur and its substitutions play an important role in not only the binding of anti-folates to GAR Tfase but also the selectivity and cellular activity (growth inhibition), thereby presenting new possibilities for the future design of potent and selective anti-folate drugs that target GAR Tfase.

Biological and Structural Evaluation of 10R- and 10S-Methylthio-DDACTHF Reveals a New Role for Sulfur in Inhibition of Glycinamide Ribonucleotide Transformylase.,Connelly S, Demartino JK, Boger DL, Wilson IA Biochemistry. 2013 Jul 30;52(30):5133-44. doi: 10.1021/bi4005182. Epub 2013 Jul, 19. PMID:23869564<ref>PMID:23869564</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>

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== References ==

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