The hydrolytic kinetic resolution (HKR) of terminal epoxides catalyzed by chiral (salen)Co(III) complex 1 x OAc affords both recovered unreacted epoxide and 1,2-diol product in highly enantioenriched form. As such, the HKR provides general access to useful, highly enantioenriched chiral building blocks that are otherwise difficult to access, from inexpensive racemic materials. The reaction has several appealing features from a practical standpoint, including the use of H(2)O as a reactant and low loadings (0.2-2.0 mol %) of a recyclable, commercially available catalyst. In addition, the HKR displays extraordinary scope, as a wide assortment of sterically and electronically varied epoxides can be resolved to > or = 99% ee. The corresponding 1,2-diols were produced in good-to-high enantiomeric excess using 0.45 equiv of H(2)O. Useful and general protocols are provided for the isolation of highly enantioenriched epoxides and diols, as well as for catalyst recovery and recycling. Selectivity factors (k(rel)) were determined for the HKR reactions by measuring the product ee at ca. 20% conversion. In nearly all cases, k(rel) values for the HKR exceed 50, and in several cases are well in excess of 200.

Angiotensin-converting enzyme-related carboxypeptidase (ACE2) is a recently identified zinc metalloprotease with carboxypeptidase activity that was identified using our genomics platform. We implemented a rational design approach to identify potent and selective ACE2 inhibitors. To this end, picomolar inhibitors of ACE2 were designed and synthesized.

Huang is an employee and shareholder of Theseus Pharmaceuticals and a former employee of ARIAD. Y. Hu is an employee of Takeda. F. Li is a former employee of ARIAD. M.T. Greenfield is a former employee of ARIAD. S.G. Zech is an employee and shareholder of Amgen Inc. and a former employee of ARIAD. B. Das is a former employee of ARIAD. N.I. Narasimhan is a former employee of ARIAD. T. Clackson is an employee and shareholder of Xilio Therapeutics and is a former employee of ARIAD. D. Dalgarno is an employee and shareholder of Theseus Pharmaceuticals and a former employee of ARIAD. W.C. Shakespeare is an employee and shareholder of Theseus Pharmaceuticals and a former employee of ARIAD. M. Fitzgerald is a former employee Research.

The Plasmodium proteasome represents a potential antimalarial drug target for compounds with activity against multiple life cycle stages. We screened a library of human proteasome inhibitors (peptidyl boronic acids) and compared activities against purified P. falciparum and human 20S proteasomes. We chose four hits that potently inhibit parasite growth and show a range of selectivities for inhibition of the growth of P. falciparum compared with human cell lines. P. falciparum was selected for resistance in vitro to the clinically used proteasome inhibitor, bortezomib, and whole genome sequencing was applied to identify mutations in the proteasome β5 subunit. Active site profiling revealed inhibitor features that enable retention of potent activity against the bortezomib-resistant line. Substrate profiling reveals P. falciparum 20S proteasome active site preferences that will inform attempts to design more selective inhibitors. This work provides a starting point for the identification of antimalarial drug leads that selectively target the P. falciparum proteasome.

A genetic approach utilizing the yeast Saccharomyces cerevisiae was used to identify the target of antifungal compounds. This analysis led to the identification of small molecule inhibitors of RNA polymerase (Pol) III from Saccharomyces cerevisiae. Three lines of evidence show that UK-118005 inhibits cell growth by targeting RNA Pol III in yeast. First, a dominant mutation in the g domain of Rpo31p, the largest subunit of RNA Pol III, confers resistance to the compound. Second, UK-118005 rapidly inhibits tRNA synthesis in wild-type cells but not in UK-118005 resistant mutants. Third, in biochemical assays, UK-118005 inhibits tRNA gene transcription in vitro by the wild-type but not the mutant Pol III enzyme. By testing analogs of UK-118005 in a template-specific RNA Pol III transcription assay, an inhibitor with significantly higher potency, ML-60218, was identified. Further examination showed that both compounds are broad-spectrum inhibitors, displaying activity against RNA Pol III transcription systems derived from Candida albicans and human cells. The identification of these inhibitors demonstrates that RNA Pol III can be targeted by small synthetic molecules.Defining the mechanism of action of small molecules in higher eukaryotes is hindered by their complexity, limited genetic methods, and protracted life cycles. In contrast, model eukaryotes are amenable to extensive genetic analyses in relatively short time frames. For example, unicellular eukaryotes, such as Saccharomyces cerevisiae and Aspergillus nidulans, have been used to rapidly elucidate the mechanism of action of many compounds, including drugs that are relevant to human therapeutics. The targets of the immunosuppressive compounds cyclosporine, FK506, and rapamycin were discovered in studies with yeast (9, 24). Resistance to cerulenin in S. cerevisiae was mapped to FAS2, and inhibition of the encoded enzyme, fatty acid synthase, was demonstrated biochemically (21). Similarly, isolation of an A. nidulans mutant resistant to a novel agricultural antifungal compound led to identification of dihydroorotate dehydrogenase as the target (15).In the present report, we extend the utility of S. cerevisiae for discovering and characterizing antifungal compounds. Our initial studies focused on UK-118005, a compound that has broad-spectrum antifungal activity. Using classical genetics, molecular biology, and biochemistry, we show that UK-118005 inhibits RNA polymerase (Pol) III. Although natural products have been identified that inhibit different RNA Pols, such as ␣-amanitin (32, 33) and tagetitoxin (34,35), this is the first example of a synthetic small molecule inhibiting RNA Pol. This finding demonstrates that cell-based screening can be a powerful method for identifying novel druggable targets.Additional antifungal structural analogs of UK-118005 were identified and further characterized. These results showed that whereas some analogs inhibit RNA Pol III as expected, others caused growth inhibition by an entirely different mechanism. Thus, yeast can be us...

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Background:The Uba6 pathway and its components play an important role in a variety of biological processes. Results: The mechanism of how Uba6 activates two distinct substrates, ubiquitin and FAT10, was characterized. Conclusion: Uba6 was shown to use a similar mechanism for activating both substrates with a greater affinity for FAT10. Significance: Relative levels of ubiquitin and FAT10 could regulate the Uba6 pathway in cells.

Aminoacyl transfer RNA (tRNA) synthetases (aaRSs) are attractive drug targets, and we present class I and II aaRSs as previously unrecognized targets for adenosine 5′-monophosphate–mimicking nucleoside sulfamates. The target enzyme catalyzes the formation of an inhibitory amino acid–sulfamate conjugate through a reaction-hijacking mechanism. We identified adenosine 5′-sulfamate as a broad-specificity compound that hijacks a range of aaRSs and ML901 as a specific reagent a specific reagent that hijacks a single aaRS in the malaria parasite Plasmodium falciparum , namely tyrosine RS ( Pf YRS). ML901 exerts whole-life-cycle–killing activity with low nanomolar potency and single-dose efficacy in a mouse model of malaria. X-ray crystallographic studies of plasmodium and human YRSs reveal differential flexibility of a loop over the catalytic site that underpins differential susceptibility to reaction hijacking by ML901.