The EXOCET Exosome Quantitation Kit from System Biosciences (SBI) is a specialized, antibody-free enzymatic assay designed to rapidly calculate the absolute number of extracellular vesicles (exosomes) in a sample. Unlike target-specific protein assays, it quantifies exosomes by measuring the catalytic activity of Acetylcholinesterase (AChE), a hydrolytic enzyme universally enriched inside these vesicles. Core Mechanism and Specifications
The Target Protein: Measures internal AChE activity rather than surface markers like CD63 or CD81.
Detection Principle: Colorimetric enzymatic reaction read at an optical density of 405 nm (OD₄₀₅).
Turnaround Speed: Yields absolute particle numbers in as little as 20 minutes.
Broad Compatibility: Validated across all tested mammalian species including human, mouse, and rat biofluids or cell lines.
Isolation Synergy: Works alongside various separation methods such as ExoQuick precipitation, chromatography, immunoaffinity capture, and standard ultracentrifugation. Step-by-Step Workflow
Exosome Lysis: Resuspended exosome pellets are treated with a specialized Lysis Buffer for 5 minutes at 37°C to release internal proteins while conserving enzyme stability.
Debris Pelleting: The lysed sample undergoes quick centrifugation at 1,500 × g to separate membrane fragments.
Reaction Setup: Prepared supernatant is loaded into a clear 96-well microtiter plate and mixed with freshly prepared EXOCET Reaction Buffer (comprising Buffer A and Buffer B).
Incubation & Readout: The assay incubates at room temperature for 10–20 minutes before immediate absorption reading at 405 nm.
Absolute Quantification: Absorbance data points are plotted directly against a standard calibration curve (calibrated by the manufacturer using NanoSight Nanoparticle Tracking Analysis) to translate enzyme activity into vesicle particle counts. Comparative Variations
The EXOCET technology family features multiple variations depending on your laboratory’s material constraints: EXOCET Exosome Quantitation Kit – System Biosciences
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