RESUMO
Recent developments of unique nucleotide probes have expanded our understanding of DNA polymerase function, providing many benefits to techniques involving next-generation sequencing (NGS) technologies. The cyclic reversible termination (CRT) method depends on efficient base-selective incorporation of reversible terminators by DNA polymerases. Most terminators are designed with 3'-O-blocking groups but are incorporated with low efficiency and fidelity. We have developed a novel class of 3'-OH unblocked nucleotides, called Lightning Terminators™, which have a terminating 2-nitrobenzyl moiety attached to hydroxymethylated nucleobases. A key structural feature of this photocleavable group displays a 'molecular tuning' effect with respect to single-base termination and improved nucleotide fidelity. Using Therminator DNA polymerase, we demonstrate that these 3'-OH unblocked terminators exhibit superior enzymatic performance compared to two other reversible terminators, 3'-O-amino-TTP and 3'-O-azidomethyl-TTP. Lightning Terminators show maximum incorporation rates (k(pol)) that range from 35 to 45 nt/s, comparable to the fastest NGS chemistries, yet with catalytic efficiencies (k(pol)/K(D)) comparable to natural nucleotides. Pre-steady-state kinetic studies of thymidine analogs revealed that the major determinant for improved nucleotide selectivity is a significant reduction in k(pol) by >1000-fold over TTP misincorporation. These studies highlight the importance of structure-function relationships of modified nucleotides in dictating polymerase performance.
Assuntos
DNA Polimerase Dirigida por DNA/metabolismo , DNA/biossíntese , Nucleotídeos de Desoxiuracil/química , DNA/química , DNA Polimerase Dirigida por DNA/química , Nucleotídeos de Desoxiuracil/metabolismo , Sequenciamento de Nucleotídeos em Larga Escala , Cinética , Nitrobenzenos/química , Nucleotídeos/química , Nucleotídeos/metabolismo , Análise de Sequência de DNARESUMO
A series of (S)-2-(2-(diethylamino)-5-(N-alkyl-N-sulfonamido)pyrimidin-4-ylamino)-3-(4-(carbamoyloxy)phenyl)propanoic acid is discovered as orally available VLA-4 antagonists. Representative compounds 11b and 11p showed efficacy in multiple in vivo animal models. The in vitro selectivity of 11p is also described.
Assuntos
Antirreumáticos/farmacologia , Integrina alfa4beta1/antagonistas & inibidores , Pirimidinas/farmacologia , Sulfonamidas/farmacologia , Animais , Antirreumáticos/administração & dosagem , Antirreumáticos/síntese química , Artrite Experimental/tratamento farmacológico , Asma/tratamento farmacológico , Adesão Celular/efeitos dos fármacos , Colágeno Tipo II/antagonistas & inibidores , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Feminino , Fibronectinas/química , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Modelos Moleculares , Conformação Molecular , Esclerose Múltipla/tratamento farmacológico , Pirimidinas/administração & dosagem , Pirimidinas/síntese química , Ratos , Ratos Endogâmicos Lew , Ratos Sprague-Dawley , Relação Estrutura-Atividade , Sulfonamidas/administração & dosagem , Sulfonamidas/síntese químicaRESUMO
We describe a novel 3'-OH unblocked reversible terminator with the potential to improve accuracy and read-lengths in next-generation sequencing (NGS) technologies. This terminator is based on 5-hydroxymethyl-2'-deoxyuridine triphosphate (HOMedUTP), a hypermodified nucleotide found naturally in the genomes of numerous bacteriophages and lower eukaryotes. A series of 5-(2-nitrobenzyloxy)methyl-dUTP analogs (dU.I-dU.V) were synthesized based on our previous work with photochemically cleavable terminators. These 2-nitrobenzyl alkylated HOMedUTP analogs were characterized with respect to incorporation, single-base termination, nucleotide selectivity and photochemical cleavage properties. Substitution at the α-methylene carbon of 2-nitrobenzyl with alkyl groups of increasing size was discovered as a key structural feature that provided for the molecular tuning of enzymatic properties such as single-base termination and improved nucleotide selectivity over that of natural nucleotides. 5-[(S)-α-tert-Butyl-2-nitrobenzyloxy]methyl-dUTP (dU.V) was identified as an efficient reversible terminator, whereby, sequencing feasibility was demonstrated in a cyclic reversible termination (CRT) experiment using a homopolymer repeat of ten complementary template bases without detectable UV damage during photochemical cleavage steps. These results validate our overall strategy of creating 3'-OH unblocked reversible terminator reagents that, upon photochemical cleavage, transform back into a natural state. Modified nucleotides based on 5-hydroxymethyl-pyrimidines and 7-deaza-7-hydroxymethyl-purines lay the foundation for development of a complete set of four reversible terminators for application in NGS technologies.
Assuntos
Nucleotídeos de Desoxiuracil/química , Análise de Sequência de DNA/métodos , DNA Polimerase Dirigida por DNA/metabolismo , Nucleotídeos de Desoxiuracil/síntese química , Nucleotídeos de Desoxiuracil/metabolismo , Processos Fotoquímicos , Reação em Cadeia da Polimerase , Moldes Genéticos , Raios UltravioletaRESUMO
The structure-activity relationship of the prime region of hydroxyethylamine BACE inhibitors is described. Variation in the aryl linker region with 5- and 6-membered heterocycles provided compounds such as 33 with improved permeability and reduced P-gp liability compared to benzyl amine analog 1.
Assuntos
Secretases da Proteína Precursora do Amiloide/antagonistas & inibidores , Secretases da Proteína Precursora do Amiloide/metabolismo , Ácido Aspártico Endopeptidases/antagonistas & inibidores , Ácido Aspártico Endopeptidases/metabolismo , Etilaminas/química , Etilaminas/farmacologia , Inibidores de Proteases/química , Inibidores de Proteases/farmacologia , Membro 1 da Subfamília B de Cassetes de Ligação de ATP/metabolismo , Doença de Alzheimer/tratamento farmacológico , Secretases da Proteína Precursora do Amiloide/química , Ácido Aspártico Endopeptidases/química , Cristalografia por Raios X , Etilaminas/síntese química , Humanos , Modelos Moleculares , Inibidores de Proteases/síntese química , Ligação Proteica , Relação Estrutura-AtividadeRESUMO
The Human Genome Project has facilitated the sequencing of many species, yet the current Sanger method is too expensive, labor intensive and time consuming to accomplish medical resequencing of human genomes en masse. Of the 'next-generation' technologies, cyclic reversible termination (CRT) is a promising method with the goal of producing accurate sequence information at a fraction of the cost and effort. The foundation of this approach is the reversible terminator (RT), its chemical and biological properties of which directly impact the performance of the sequencing technology. Here, we have discovered a novel paradigm in RT chemistry, the attachment of a photocleavable, 2-nitrobenzyl group to the N(6)-position of 2'-deoxyadenosine triphosphate (dATP), which, upon incorporation, terminates DNA synthesis. The 3'-OH group of the N(6)-(2-nitrobenzyl)-dATP remains unblocked, providing favorable incorporation and termination properties for several commercially available DNA polymerases while maintaining good discrimination against mismatch incorporations. Upon removal of the 2-nitrobenzyl group with UV light, the natural nucleotide is restored without molecular scarring. A five-base experiment, illustrating the exquisite, stepwise addition through a homopolymer repeat, demonstrates the applicability of the N(6)-(2-nitrobenzyl)-dATP as an ideal RT for CRT sequencing.