Enzyme Aptamer Screening Service is a specialized contract research service where providers employ SELEX (Systematic Evolution of Ligands by EXponential Enrichment) to discover aptamers that bind with high specificity and affinity to a target enzyme. These aptamers can be designed not only to bind but also to modulate the enzyme's activity (inhibit or activate), making them powerful tools for therapeutics, diagnostics, and biochemical research. Key Differentiators from Antibody Screening: Functional Screening: A major goal is often to identify inhibitory or activating aptamers. Therefore, the screening process may incorporate activity-based selection or functional assays early on. Target Site Complexity: The target can be the entire enzyme, its active site, an allosteric site, or a specific conformational state (e.g., open vs. closed). Conformational Sensitivity: Enzymes are dynamic. Aptamers can be selected to recognize a specific functional conformation, which is a unique advantage. Typical Screening Workflow: 1. Project Design & Target Preparation: Define Objective: Is the goal pure detection, potent inhibition, allosteric modulation, or capturing a specific enzyme form? Enzyme Quality: Requires a highly pure, functional, and correctly folded enzyme. Activity assays confirm functionality. Selection Strategy: Choice of Toggle SELEX (for broad species cross-reactivity), Capture SELEX, or innovative methods like ExSELEX (for complex biological fluids). 2. The SELEX Process with a Functional Focus: Binding & Stringency: Standard incubation, washing, and elution cycles are performed. Functional Partitioning (Optional…
Why Target Protein Kinases with Aptamers? Protein kinases are a large family of enzymes that regulate almost all cellular processes by phosphorylating target proteins. Their dysregulation is a hallmark of many diseases, especially cancer, making them prime therapeutic targets. Advantages of Aptamers over Traditional Kinase Inhibitors: High Specificity: Can be selected to distinguish between highly conserved kinase family members or even between active/inactive conformations. Modifiable Chemistry: Easy chemical modification for stability (e.g., 2'-F, 2'-O-methyl) and labeling (e.g., fluorophores, biotin). Non-Immunogenic: Unlike antibodies, they are chemically synthesized, reducing batch-to-batch variability. Reversible Inhibition: Typically act as competitive inhibitors, which can be desirable for certain therapeutic strategies. Cell-Permeable Versions: Spiegelmers (L-aptamers) or nanoparticle conjugation can enable intracellular targeting. Core Screening Service Workflow (SELEX) The service revolves around SELEX (Systematic Evolution of Ligands by EXponential Enrichment), specifically optimized for kinases. 1. Project Design & Library Selection: Target Definition: Which kinase? Which conformation (active, inactive, substrate-bound)? Which domain (catalytic, regulatory)? Library Design: Standard DNA/RNA libraries or modified (e.g., 2'-F pyrimidines for nuclease resistance). Library diversity is typically >10^14 unique sequences. 2. Target Preparation: Protein Quality is Critical: The kinase must be highly pure, correctly folded, and functional. Services often use recombinant kinases with tags (GST, His) for immobilization. Immobilization Strategy: Crucial step. Common methods include: Biotin-Streptavidin: Biotinylated…
