RESUMO
Glycogen synthase kinase-3 (GSK-3) regulates multiple cellular processes in diabetes, oncology, and neurology. N-(3-(1H-1,2,4-triazol-1-yl)propyl)-5-(3-chloro-4-methoxyphenyl)oxazole-4-carboxamide (PF-04802367 or PF-367) has been identified as a highly potent inhibitor, which is among the most selective antagonists of GSK-3 to date. Its efficacy was demonstrated in modulation of tau phosphorylation inâ vitro and inâ vivo. Whereas the kinetics of PF-367 binding in brain tissues are too fast for an effective therapeutic agent, the pharmacokinetic profile of PF-367 is ideal for discovery of radiopharmaceuticals for GSK-3 in the central nervous system. A (11) C-isotopologue of PF-367 was synthesized and preliminary PET imaging studies in non-human primates confirmed that we have overcome the two major obstacles for imaging GSK-3, namely, reasonable brain permeability and displaceable binding.
Assuntos
Encéfalo/efeitos dos fármacos , Encéfalo/diagnóstico por imagem , Neuroimagem , Oxazóis/farmacologia , Tomografia por Emissão de Pósitrons , Inibidores de Proteínas Quinases/farmacologia , Triazóis/farmacologia , Proteínas tau/antagonistas & inibidores , Encéfalo/metabolismo , Cristalografia por Raios X , Relação Dose-Resposta a Droga , Quinase 3 da Glicogênio Sintase/antagonistas & inibidores , Quinase 3 da Glicogênio Sintase/metabolismo , Humanos , Modelos Moleculares , Estrutura Molecular , Oxazóis/síntese química , Oxazóis/química , Fosforilação/efeitos dos fármacos , Inibidores de Proteínas Quinases/síntese química , Inibidores de Proteínas Quinases/química , Triazóis/síntese química , Triazóis/química , Proteínas tau/metabolismoRESUMO
Peptidoglycan synthesis is an underutilized drug target in Mycobacterium tuberculosis (Mtb). Diazabicyclooctanes (DBOs) are a class of broad-spectrum ß-lactamase inhibitors that also inhibit certain peptidoglycan transpeptidases that are important in mycobacterial cell wall synthesis. We evaluated the DBO durlobactam as an inhibitor of BlaC, the Mtb ß-lactamase, and multiple Mtb peptidoglycan transpeptidases (PonA1, LdtMt1, LdtMt2, LdtMt3, and LdtMt5). Timed electrospray ionization mass spectrometry (ESI-MS) captured acyl-enzyme complexes with BlaC and all transpeptidases except LdtMt5. Inhibition kinetics demonstrated durlobactam was a potent and efficient DBO inhibitor of BlaC (KI app 9.2 ± 0.9 µM, k2/K 5600 ± 560 M-1 s-1) and similar to clavulanate (KI app 3.3 ± 0.6 µM, k2/K 8400 ± 840 M-1 s-1); however, durlobactam had a lower turnover number (tn = kcat/kinact) than clavulanate (1 and 8, respectively). KI app values with durlobactam and clavulanate were similar for peptidoglycan transpeptidases, but ESI-MS captured durlobactam complexes at more time points. Molecular docking and simulation demonstrated several productive interactions of durlobactam in the active sites of BlaC, PonA1, and LdtMt2. Antibiotic susceptibility testing was conducted on 11 Mtb isolates with amoxicillin, ceftriaxone, meropenem, imipenem, clavulanate, and durlobactam. Durlobactam had a minimum inhibitory concentration (MIC) range of 0.5-16 µg/mL, similar to the ranges for meropenem (1-32 µg/mL) and imipenem (0.5-64 µg/mL). In ß-lactam + durlobactam combinations (1:1 mass/volume), MICs were lowered 4- to 64-fold for all isolates except one with meropenem-durlobactam. This work supports further exploration of novel ß-lactamase inhibitors that target BlaC and Mtb peptidoglycan transpeptidases.
Assuntos
Aminoaciltransferases , Antituberculosos , Mycobacterium tuberculosis , Inibidores de beta-Lactamases , beta-Lactamases , Aminoaciltransferases/antagonistas & inibidores , Antituberculosos/farmacologia , Antituberculosos/química , Compostos Azabicíclicos/farmacologia , Compostos Azabicíclicos/química , Proteínas de Bactérias/antagonistas & inibidores , Proteínas de Bactérias/química , Inibidores de beta-Lactamases/farmacologia , Inibidores de beta-Lactamases/química , beta-Lactamases/metabolismo , beta-Lactamases/química , Cinética , Testes de Sensibilidade Microbiana , Simulação de Acoplamento Molecular , Mycobacterium tuberculosis/efeitos dos fármacos , Mycobacterium tuberculosis/enzimologiaRESUMO
Selective phosphodiesterase 2 (PDE2) inhibitors are shown to have efficacy in a rat model of osteoarthritis (OA) pain. We identified potent, selective PDE2 inhibitors by optimizing residual PDE2 activity in a series of phosphodiesterase 4 (PDE4) inhibitors, while minimizing PDE4 inhibitory activity. These newly designed PDE2 inhibitors bind to the PDE2 enzyme in a cGMP-like binding mode orthogonal to the cAMP-like binding mode found in PDE4. Extensive structure activity relationship studies ultimately led to identification of pyrazolodiazepinone, 22, which was >1000-fold selective for PDE2 over recombinant, full length PDEs 1B, 3A, 3B, 4A, 4B, 4C, 7A, 7B, 8A, 8B, 9, 10 and 11. Compound 22 also retained excellent PDE2 selectivity (241-fold to 419-fold) over the remaining recombinant, full length PDEs, 1A, 4D, 5, and 6. Compound 22 exhibited good pharmacokinetic properties and excellent oral bioavailability (F=78%, rat). In an in vivo rat model of OA pain, compound 22 had significant analgesic activity 1 and 3h after a single, 10 mg/kg, subcutaneous dose.
Assuntos
Azepinas/química , Azirinas/química , Nucleotídeo Cíclico Fosfodiesterase do Tipo 2/antagonistas & inibidores , Di-Hidropiridinas/química , Inibidores de Fosfodiesterase/química , Pirazóis/química , Analgésicos/química , Analgésicos/farmacocinética , Analgésicos/uso terapêutico , Animais , Azepinas/farmacocinética , Azepinas/uso terapêutico , Azirinas/farmacocinética , Azirinas/uso terapêutico , Sítios de Ligação , Domínio Catalítico , Cristalografia por Raios X , Nucleotídeo Cíclico Fosfodiesterase do Tipo 2/metabolismo , Di-Hidropiridinas/farmacocinética , Di-Hidropiridinas/uso terapêutico , Modelos Animais de Doenças , Avaliação Pré-Clínica de Medicamentos , Meia-Vida , Osteoartrite/tratamento farmacológico , Inibidores da Fosfodiesterase 4/química , Inibidores de Fosfodiesterase/farmacocinética , Inibidores de Fosfodiesterase/uso terapêutico , Ligação Proteica , Pirazóis/farmacocinética , Pirazóis/uso terapêutico , Ratos , Relação Estrutura-AtividadeRESUMO
We identified potent, selective PDE2 inhibitors by optimizing residual PDE2 activity in a series of PDE4 inhibitors, while simultaneously minimizing PDE4 activity. These newly designed PDE2 inhibitors bind to the PDE2 enzyme in a cGMP-like mode in contrast to the cAMP-like binding mode found in PDE4. Structure activity relationship studies coupled with an inhibitor bound crystal structure in the active site of the catalytic domain of PDE2 identified structural features required to minimize PDE4 inhibition while simultaneously maximizing PDE2 inhibition.
Assuntos
Azirinas/química , Nucleotídeo Cíclico Fosfodiesterase do Tipo 2/antagonistas & inibidores , Nucleotídeo Cíclico Fosfodiesterase do Tipo 4/química , Di-Hidropiridinas/química , Inibidores da Fosfodiesterase 4/química , Inibidores de Fosfodiesterase/química , Animais , Azirinas/metabolismo , Azirinas/uso terapêutico , Sítios de Ligação , Domínio Catalítico , Cristalografia por Raios X , Nucleotídeo Cíclico Fosfodiesterase do Tipo 2/metabolismo , Nucleotídeo Cíclico Fosfodiesterase do Tipo 4/metabolismo , Di-Hidropiridinas/metabolismo , Di-Hidropiridinas/uso terapêutico , Modelos Animais de Doenças , Avaliação Pré-Clínica de Medicamentos , Osteoartrite/tratamento farmacológico , Inibidores de Fosfodiesterase/metabolismo , Inibidores de Fosfodiesterase/uso terapêutico , Ligação Proteica , Relação Estrutura-AtividadeRESUMO
Novel siderophore-linked monobactams with in vitro and in vivo anti-microbial activity against MDR Gram-negative pathogens are described.
Assuntos
Farmacorresistência Bacteriana Múltipla/efeitos dos fármacos , Bactérias Gram-Negativas/efeitos dos fármacos , Infecções por Bactérias Gram-Negativas/tratamento farmacológico , Monobactamas/farmacologia , Animais , Sítios de Ligação/efeitos dos fármacos , Proteínas Sanguíneas/química , Cristalografia por Raios X , Relação Dose-Resposta a Droga , Infecções por Bactérias Gram-Negativas/microbiologia , Humanos , Camundongos , Testes de Sensibilidade Microbiana , Modelos Moleculares , Estrutura Molecular , Monobactamas/síntese química , Monobactamas/química , Ratos , Relação Estrutura-AtividadeRESUMO
Modern drug discovery is contingent on identifying lead compounds and rapidly synthesizing analogues. The use of a common pharmacophore to direct multiple and divergent C-H functionalizations of lead compounds is a particularly attractive approach. Herein, we demonstrate the viability of late-stage diversification through the divergent C-H functionalization of sulfonamides, an important class of pharmacophores found in nearly 200 drugs currently on the market, including the non-steroidal anti-inflammatory blockbuster drug celecoxib. We developed a set of six categorically different sulfonamide C-H functionalization reactions (olefination, arylation, alkylation, halogenation, carboxylation, and carbonylation), each representing a distinct handle for further diversification to reach a large number of analogues. We then performed late-stage, site-selective diversification of a sulfonamide drug candidate containing multiple potentially reactive C-H bonds to synthesize directly novel celecoxib analogues as potential cyclooxygenase-II (COX-2)-specific inhibitors. Together with other recently developed practical directing groups, such as CONHOMe and CONHC(6)F(5), sulfonamide directing groups demonstrate that the auxiliary approach established in asymmetric catalysis can be equally effective in developing broadly useful C-H activation reactions.
Assuntos
Inibidores de Ciclo-Oxigenase 2/química , Descoberta de Drogas/métodos , Pirazóis/química , Sulfonamidas/química , Alcenos/química , Catálise , Celecoxib , Inibidores de Ciclo-Oxigenase 2/isolamento & purificação , Pirazóis/isolamento & purificação , Sulfonamidas/isolamento & purificaçãoRESUMO
Serious infections caused by multidrug-resistant (MDR) organisms (Klebsiella pneumoniae, Pseudomonas aeruginosa, Acinetobacter baumannii) present a critical need for innovative drug development. Herein, we describe the preclinical evaluation of YU253911, 2, a novel γ-lactam siderophore antibiotic with potent antimicrobial activity against MDR Gram-negative pathogens. Penicillin-binding protein (PBP) 3 was shown to be a target of 2 using a binding assay with purified P. aeruginosa PBP3. The specific binding interactions with P. aeruginosa were further characterized with a high-resolution (2.0 Å) X-ray structure of the compound's acylation product in P. aeruginosa PBP3. Compound 2 was shown to have a concentration >1 µg/ml at the 6 h time point when administered intravenously or subcutaneously in mice. Employing a meropenem resistant strain of P. aeruginosa, 2 was shown to have dose-dependent efficacy at 50 and 100 mg/kg q6h dosing in a mouse thigh infection model. Lastly, we showed that a novel γ-lactam and ß-lactamase inhibitor (BLI) combination can effectively lower minimum inhibitory concentrations (MICs) against carbapenem resistant Acinetobacter spp. that demonstrated decreased susceptibility to 2 alone.
Assuntos
Antibacterianos/farmacologia , Farmacorresistência Bacteriana Múltipla/efeitos dos fármacos , Klebsiella pneumoniae/efeitos dos fármacos , Lactamas/farmacologia , Sideróforos/farmacologia , Acinetobacter baumannii/efeitos dos fármacos , Antibacterianos/síntese química , Antibacterianos/química , Relação Dose-Resposta a Droga , Lactamas/síntese química , Lactamas/química , Testes de Sensibilidade Microbiana , Estrutura Molecular , Pseudomonas aeruginosa/efeitos dos fármacos , Sideróforos/síntese química , Sideróforos/química , Relação Estrutura-AtividadeRESUMO
This report describes the use of Pd(II)/bis-sulfoxide 1 catalyzed intra- and intermolecular allylic C-H amination reactions to rapidly diversify structures containing a sensitive ß-lactam core similar to that found in the monobactam antibiotic Aztreonam. Pharmacologically interesting oxazolidinone, oxazinanone, and linear amine motifs are rapidly installed with predictable and high selectivities under conditions that use limiting amounts of substrate. Additionally, we demonstrate for the first time that intramolecular C-H amination processes may be accelerated using catalytic amounts of a Lewis acid co-catalyst [Cr(III)(salen)Cl 2].
RESUMO
Treatment of multidrug-resistant Gram-negative bacterial pathogens represents a critical clinical need. Here, we report a novel γ-lactam pyrazolidinone that targets penicillin-binding proteins (PBPs) and incorporates a siderophore moiety to facilitate uptake into the periplasm. The MIC values of γ-lactam YU253434, 1, are reported along with the finding that 1 is resistant to hydrolysis by all four classes of ß-lactamases. The druglike characteristics and mouse PK data are described along with the X-ray crystal structure of 1 binding to its target PBP3.
Assuntos
Antibacterianos/farmacologia , Farmacorresistência Bacteriana Múltipla/efeitos dos fármacos , Lactamas/química , Sideróforos/química , Animais , Antibacterianos/síntese química , Antibacterianos/metabolismo , Antibacterianos/farmacocinética , Proteínas de Bactérias/antagonistas & inibidores , Proteínas de Bactérias/metabolismo , Sítios de Ligação , Domínio Catalítico , Cristalografia por Raios X , Bactérias Gram-Negativas/efeitos dos fármacos , Meia-Vida , Lactamas/metabolismo , Lactamas/farmacocinética , Lactamas/farmacologia , Camundongos , Testes de Sensibilidade Microbiana , Simulação de Acoplamento Molecular , Proteínas de Ligação às Penicilinas/antagonistas & inibidores , Proteínas de Ligação às Penicilinas/metabolismo , Pseudomonas aeruginosa/metabolismo , Sideróforos/metabolismoRESUMO
A new series of MEK1 inhibitors, the 4-anilino-5-carboxamido-2-pyridones, were designed and synthesized using a combination of medicinal chemistry, computational chemistry, and structural elucidation. The effect of variation in the carboxamide side chain, substitution on the pyridone nitrogen, and replacement of the 4'-iodide were all investigated. This study afforded several compounds which were either equipotent or more potent than the clinical candidate CI-1040 (1) in an isolated enzyme assay, as well as murine colon carcinoma (C26) cells, as measured by suppression of phosphorylated ERK substrate. Most notably, pyridone 27 was found to be more potent than 1 in vitro and produced a 100% response rate at a lower dose than 1, when tested for in vivo efficacy in animals bearing C26 tumors.
Assuntos
Amidas/síntese química , Compostos de Anilina/síntese química , Antineoplásicos/síntese química , MAP Quinase Quinase 1/antagonistas & inibidores , MAP Quinase Quinase 2/antagonistas & inibidores , Piridonas/síntese química , Amidas/química , Amidas/farmacologia , Compostos de Anilina/química , Compostos de Anilina/farmacologia , Animais , Antineoplásicos/química , Antineoplásicos/farmacologia , Benzamidas/farmacologia , Linhagem Celular Tumoral , Ensaios de Seleção de Medicamentos Antitumorais , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , MAP Quinase Quinase 1/química , MAP Quinase Quinase 2/química , Masculino , Camundongos , Modelos Moleculares , Transplante de Neoplasias , Fosforilação , Piridonas/química , Piridonas/farmacologia , Ratos , Relação Estrutura-AtividadeRESUMO
Fluoride is a ubiquitous anion that inhibits a wide variety of metabolic processes. Here, we report the identification of a series of compounds that enhance fluoride toxicity in Escherichia coli and Streptococcus mutans. These molecules were isolated by using a high-throughput screen (HTS) for compounds that increase intracellular fluoride levels as determined via a fluoride riboswitch reporter fusion construct. A series of derivatives were synthesized to examine structure-activity relationships, leading to the identification of compounds with improved activity. Thus, we demonstrate that small molecule fluoride toxicity agonists can be identified by HTS from existing chemical libraries by exploiting a natural fluoride riboswitch. In addition, our findings suggest that some molecules might be further optimized to function as binary antibacterial agents when combined with fluoride.
Assuntos
Antibacterianos/química , Fluoretos/química , Fluoretos/toxicidade , Antibacterianos/síntese química , Antibacterianos/farmacologia , Escherichia coli/efeitos dos fármacos , Fluoretos/agonistas , Ensaios de Triagem em Larga Escala , Testes de Sensibilidade Microbiana , Riboswitch , Streptococcus mutans/efeitos dos fármacos , Relação Estrutura-AtividadeRESUMO
This study demonstrates that ΔlogP(oct-tol) (difference between logP(octanol) and logP(toluene)) describes compounds propensity to form intramolecular hydrogen bonds (IMHB) and may be considered a privileged molecular descriptor for use in drug discovery and for prediction of IMHB in drug candidates. We identified experimental protocols for acquiring reliable ΔlogP(oct-tol) values on a set of compounds representing IMHB motifs most prevalent in medicinal chemistry, mainly molecules capable of forming 6-, 7-member IMHB rings. Furthermore, computational ΔlogP(oct-tol) values obtained with COSMO-RS software provided a good estimate of experimental results and can be used prospectively to assess IMHB. The proposed interpretation method based on ΔlogP(oct-tol) data allowed categorization of the compounds into 2 groups: with high propensity to form IMHB and poor propensity or poor relevance of IMHB. The relative (1)H NMR chemical shift of an exchangeable proton was used to verify presence of IMHB and to validate the IMHB interpretation scheme.
Assuntos
Descoberta de Drogas/métodos , Octanóis/química , Tolueno/química , Química Farmacêutica , Cristalografia por Raios X , Ligação de Hidrogênio , Modelos Moleculares , Conformação Molecular , Reprodutibilidade dos Testes , SoftwareRESUMO
Herein we describe the structure-aided design and synthesis of a series of pyridone-conjugated monobactam analogues with in vitro antibacterial activity against clinically relevant Gram-negative species including Pseudomonas aeruginosa , Klebsiella pneumoniae , and Escherichia coli . Rat pharmacokinetic studies with compound 17 demonstrate low clearance and low plasma protein binding. In addition, evidence is provided for a number of analogues suggesting that the siderophore receptors PiuA and PirA play a role in drug uptake in P. aeruginosa strain PAO1.
Assuntos
Antibacterianos/farmacologia , Bactérias Gram-Negativas/efeitos dos fármacos , Monobactamas/farmacologia , Piridonas/farmacologia , Animais , Antibacterianos/química , Antibacterianos/farmacocinética , Escherichia coli/efeitos dos fármacos , Concentração Inibidora 50 , Klebsiella pneumoniae/efeitos dos fármacos , Masculino , Testes de Sensibilidade Microbiana , Estrutura Molecular , Monobactamas/química , Monobactamas/farmacocinética , Pseudomonas aeruginosa/efeitos dos fármacos , Piridonas/química , Piridonas/farmacocinética , Ratos , Ratos WistarRESUMO
Tandem reaction sequences that selectively convert multiple C-H bonds of abundant hydrocarbon feedstocks to functionalized materials enable rapid buildup of molecular complexity in an economical way. A tandem C-H amination/vinylic C-H arylation reaction sequence is described under Pd(II)/sulfoxide-catalysis that furnishes a wide range of α- and ß-homophenylalanine precursors from commodity α-olefins and readily available aryl boronic acids. General routes to enantiopure amino acid esters and densely functionalized homophenylalanine derivatives are demonstrated.
Assuntos
Alcenos/química , Aminoácidos/síntese química , Aminação , Aminoácidos/química , Catálise , Estrutura Molecular , EstereoisomerismoRESUMO
Thymidylate kinase (TMK) is a potential chemotherapeutic target because it is directly involved in the synthesis of an essential component, thymidine triphosphate, in DNA replication. All reported TMK inhibitors are thymidine analogues, which might retard their development as potent therapeutics due to cell permeability and off-target activity against human TMK. A small molecule hit (1, IC(50) = 58 µM), which has reasonable inhibition potency against Pseudomonas aeruginosa TMK (PaTMK), was identified by the analysis of the binding mode of thymidine or TP(5)A in a PaTMK homology model. This hit (1) was cocrystallized with PaTMK, and several potent PaTMK inhibitors (leads, 46, 47, 48, and 56, IC(50) = 100-200 nM) were synthesized using computer-aided design approaches including virtual synthesis/screening, which was used to guide the design of inhibitors. The binding mode of the optimized leads in PaTMK overlaps with that of other bacterial TMKs but not with human TMK, which shares few common features with the bacterial enzymes. Therefore, the optimized TMK inhibitors described here should be useful for the development of antibacterial agents targeting TMK without undesired off-target effects. In addition, an inhibition mechanism associated with the LID loop, which mimics the process of phosphate transfer from ATP to dTMP, was proposed based on X-ray cocrystal structures, homology models, and structure-activity relationship results.
Assuntos
Antibacterianos/síntese química , Imidazóis/síntese química , Núcleosídeo-Fosfato Quinase/antagonistas & inibidores , Pseudomonas aeruginosa/enzimologia , Piridinas/síntese química , Pirimidinas/síntese química , Timidina/química , Antibacterianos/química , Antibacterianos/farmacologia , Cristalografia por Raios X , Humanos , Imidazóis/química , Imidazóis/farmacologia , Testes de Sensibilidade Microbiana , Modelos Moleculares , Conformação Molecular , Mimetismo Molecular , Núcleosídeo-Fosfato Quinase/química , Ligação Proteica , Pseudomonas aeruginosa/efeitos dos fármacos , Piridinas/química , Piridinas/farmacologia , Pirimidinas/química , Pirimidinas/farmacologia , Alinhamento de SequênciaRESUMO
In this paper, we present the synthesis and SAR as well as selectivity, pharmacokinetic, and infection model data for representative analogues of a novel series of potent antibacterial LpxC inhibitors represented by hydroxamic acid.
Assuntos
Amidoidrolases/antagonistas & inibidores , Antibacterianos/síntese química , Compostos de Bifenilo/síntese química , Ácidos Hidroxâmicos/síntese química , Éteres Fenílicos/síntese química , Infecções por Pseudomonas/tratamento farmacológico , Sulfetos/síntese química , Sulfonas/síntese química , Animais , Antibacterianos/química , Antibacterianos/farmacologia , Compostos de Bifenilo/química , Compostos de Bifenilo/farmacologia , Domínio Catalítico , Cristalografia por Raios X , Farmacorresistência Bacteriana , Ligação de Hidrogênio , Ácidos Hidroxâmicos/química , Ácidos Hidroxâmicos/farmacologia , Camundongos , Modelos Moleculares , Conformação Molecular , Éteres Fenílicos/química , Éteres Fenílicos/farmacologia , Pseudomonas aeruginosa , Ratos , Estereoisomerismo , Relação Estrutura-Atividade , Sulfetos/química , Sulfetos/farmacologia , Sulfonas/química , Sulfonas/farmacologiaRESUMO
An efficient method was developed for the synthesis of 2-methylene-4-substituted ethyl butyrates via cyclopropyl opening followed by a Wittig reaction. The desired products were formed in a two-step, one-pot reaction sequence. Alternatively, the key intermediate ylide 2 was isolable and could be stored under oxygen-free conditions and subsequently utilized. A variety of nucleophiles were found to open the commercially available cyclopropane 1. The resulting ylide reacted with aldehydes to provide E-olefinic products.
Assuntos
Boratos/química , Compostos Organofosforados/química , Aldeídos/química , Ciclização , Estrutura MolecularRESUMO
A novel class of reversible inhibitors of Interleukin-1beta-converting enzyme (ICE, caspase-1) were discovered by iterative structure-based design. Guided by the X-ray crystal structure of analogues 1, 7 and 10 bound to ICE, we have designed a nonpeptide series of small molecule inhibitors. These compounds incorporate an arylsulfonamide moiety which replaces Val-His unit (P3-P2 residues) amino acids of the native substrate. The synthesis of the core structure, structure-activity relationships (SARs), and proposed binding orientation based on molecular modeling studies for this series of ICE inhibitors are described.