Zymogen activation: a new system for homogeneous ligand-binding assay

Area of Science:

• Biochemistry
• Analytical Chemistry
• Biotechnology

Background:

• Ligand-binding assays are crucial for detecting biomolecules.
• Existing methods, such as immunoassays, often rely on radioisotopes, posing limitations.
• The blood-coagulation cascade offers a complex enzymatic system with potential for assay development.

Purpose of the Study:

• To develop a novel, highly sensitive ligand-binding assay for biotin detection.
• To leverage the blood-coagulation cascade for enhanced assay sensitivity.
• To establish a radioisotope-independent method for analyte quantification.

Main Methods:

• Utilized a two-step enzymatic cascade involving Factor X and prothrombin zymogens.
• Employed Russell's viper venom (RVV) to initiate the cascade.
• Covalently coupled biotin to Factor X as the analyte.
• Monitored thrombin activity using a chromogenic substrate.
• Investigated competitive inhibition by free biotin in the presence of avidin.

Main Results:

• Achieved enhanced sensitivity through successive enzyme active site generation.
• Demonstrated a linear dose-response curve for biotin from 20 to 100 nmol/L.
• Showcased competitive binding of biotin to overcome avidin-mediated inhibition.
• Established a radioisotope-independent assay with improved sensitivity compared to traditional immunoassays.

Conclusions:

• The developed assay provides a sensitive and reliable method for biotin quantification.
• The approach offers improved sensitivity over many radioisotope-independent immunoassay methods.
• This cascade-based assay methodology may be adaptable for detecting a wide range of analytes.