Biomedical subjects

Kristine Svenson

Publications and source records attributed to Kristine Svenson.

7 recordsLinked to original sources

PubMed2006

Acylguanidines as small-molecule beta-secretase inhibitors.

BACE1 is an aspartyl protease responsible for cleaving amyloid precursor protein to liberate Abeta, which aggregates leading to plaque deposits implicated in Alzheimer's disease. We have identified small-molecule acylguanidine inhibitors of BACE1. Crystallographic studies show that these compounds form unique hydrogen-bonding interactions with the catalytic site aspartic acids and stabilize the protein in a flap-open conformation. Structure-based optimization led to the identification of potent analogs, such as 10d (BACE1 IC(50) = 110 nM).

Amyloid Precursor Protein Secretases↗

PubMed2006

Discovery of proline sulfonamides as potent and selective hepatitis C virus NS5b polymerase inhibitors. Evidence for a new NS5b polymerase binding site.

Through high throughput screening, substituted proline sulfonamide 6 was identified as HCV NS5b RNA-dependent RNA polymerase inhibitor. Optimization of various regions of the lead molecule resulted in compounds that displayed good potency and selectivity. The crystal structure of 6 and NS5b polymerase complex confirmed the binding near the active site region. The optimization approach and SAR are discussed in detail.

Antiviral Agents↗

PubMed2006

A novel approach to identifying beta-secretase inhibitors: bis-statine peptide mimetics discovered using structure and spot synthesis.

Beta-secretase 1 (BACE1) is an aspartic protease believed to play a critical role in Alzheimer's disease. Inhibitors of this enzyme have been designed by incorporating the non-cleavable hydroxyethylene and statine isosteres into peptides corresponding to BACE1 substrate sequences. We sought to develop new methods to quickly characterize and optimize inhibitors based on the statine core. Minimal sequence requirements for binding were first established using both crystallography and peptide spot synthesis. These shortened peptide inhibitors were then optimized by using spot synthesis to perform iterative cycles of substitution and deletion. The present study resulted in the identification of novel "bis-statine" inhibitors shown by crystallography to have a unique binding mode. Our results demonstrate the application of peptide spot synthesis as an effective method for enhancing peptidomimetic drug discovery.

Amino Acid Sequence↗

PubMed2006

3,5-dioxopyrazolidines, novel inhibitors of UDP-N- acetylenolpyruvylglucosamine reductase (MurB) with activity against gram-positive bacteria.

A series of 3,5-dioxopyrazolidines was identified as novel inhibitors of UDP-N-acetylenolpyruvylglucosamine reductase (MurB). Compounds 1 to 3, which are 1,2-bis(4-chlorophenyl)-3,5-dioxopyrazolidine-4-carboxamides, inhibited Escherichia coli MurB, Staphyloccocus aureus MurB, and E. coli MurA with 50% inhibitory concentrations (IC50s) in the range of 4.1 to 6.8 microM, 4.3 to 10.3 microM, and 6.8 to 29.4 microM, respectively. Compound 4, a C-4-unsubstituted 1,2-bis(3,4-dichlorophenyl)-3,5-dioxopyrazolidine, showed moderate inhibitory activity against E. coli MurB, S. aureus MurB, and E. coli MurC (IC50s, 24.5 to 35 microM). A fluorescence-binding assay indicated tight binding of compound 3 with E. coli MurB, giving a dissociation constant of 260 nM. Structural characterization of E. coli MurB was undertaken, and the crystal structure of a complex with compound 4 was obtained at 2.4 A resolution. The crystal structure indicated the binding of a compound at the active site of MurB and specific interactions with active-site residues and the bound flavin adenine dinucleotide cofactor. Peptidoglycan biosynthesis studies using a strain of Staphylococcus epidermidis revealed reduced peptidoglycan biosynthesis upon incubation with 3,5-dioxopyrazolidines, with IC50s of 0.39 to 11.1 microM. Antibacterial activity was observed for compounds 1 to 3 (MICs, 0.25 to 16 microg/ml) and 4 (MICs, 4 to 8 microg/ml) against gram-positive bacteria including methicillin-resistant S. aureus, vancomycin-resistant Enterococcus faecalis, and penicillin-resistant Streptococcus pneumoniae.

Anti-Bacterial Agents↗

PubMed2005

Synthesis and structure-activity relationship of novel 6-aryl-1,4-dihydrobenzo[d][1,3]oxazine-2-thiones as progesterone receptor modulators leading to the potent and selective nonsteroidal progesterone receptor agonist tanaproget.

Tanaproget represents a potential first-in-class nonsteroidal PR agonist for contraception with improved safety and side effect profiles versus currently available steroidal oral contraceptives. Additional SAR, biological activity, and structural information from a tanaproget/hPR-LBD (hPR-LBD = human progesterone receptor ligand binding domain) cocrystal structure will also be presented.

Alkaline Phosphatase↗

PubMed2004

Automated systems for protein crystallization.

Growth of high quality crystals is often the most difficult step in the determination of protein structures by X-ray diffraction. Automation can improve the success of this process both by reducing the amount of protein required for each screen and by relieving the tedium of setting up crystallization experiments by hand. We have been using an automated system for the design and execution of hanging drop crystallization experiments for the last two years. The system includes robots for the preparation of solutions, setup of hanging drops, and automated imaging, as well as a new software package (RoCKS) for managing all phases of the crystallization process. Here, we review the fundamentals of automated protein crystallization and present results from our comparisons of various approaches to screening.

Chemistry Techniques, Analytical↗

PubMed2003

Catalytically active MAP KAP kinase 2 structures in complex with staurosporine and ADP reveal differences with the autoinhibited enzyme.

MAP KAP kinase 2 (MK2), a Ser/Thr kinase, plays a crucial role in the inflammatory process. We have determined the crystal structures of a catalytically active C-terminal deletion form of human MK2, residues 41-364, in complex with staurosporine at 2.7 A and with ADP at 3.2 A, revealing overall structural similarity with other Ser/Thr kinases. Kinetic analysis reveals that the K(m) for ATP is very similar for MK2 41-364 and p38-activated MK2 41-400. Conversely, the catalytic rate and binding for peptide substrate are dramatically reduced in MK2 41-364. However, phosphorylation of MK2 41-364 by p38 restores the V(max) and K(m) for peptide substrate to values comparable to those seen in p38-activated MK2 41-400, suggesting a mechanism for regulation of enzyme activity.

Adenosine Diphosphate↗