A radioimmunoassay for chicken avidin. Comparison with a [14C]biotin-binding method

Area of Science:

• Biochemistry
• Immunology
• Analytical Chemistry

Background:

• Avidin is a key protein in egg white with high biotin-binding affinity.
• Accurate quantification of avidin is crucial for various biological and biotechnological applications.
• Existing methods for avidin quantification have limitations in sensitivity and tissue applicability.

Purpose of the Study:

• To develop and validate a novel double-antibody solid-phase radioimmunoassay for quantifying chicken avidin.
• To compare the performance of the developed radioimmunoassay with a conventional [14C]biotin/bentonite method.
• To assess the applicability of the radioimmunoassay across different chicken tissues.

Main Methods:

• Avidin was labeled with Iodine-125 (125I) using the chloramine-T method.
• A double-antibody solid-phase system was employed for separating bound and free avidin.
• Standard curves were generated on a logit-log scale, and cross-reactivity with ovalbumin was assessed.

Main Results:

• The radioimmunoassay demonstrated linearity from 1-2 to 100-200 ng/ml of avidin.
• Cross-reactivity with ovalbumin was minimal (<0.015%).
• The radioimmunoassay provided superior recovery of avidin from chicken liver and kidney compared to the [14C]biotin/bentonite method.

Conclusions:

• The developed double-antibody solid-phase radioimmunoassay is a sensitive and reliable method for chicken avidin quantification.
• This assay exhibits broad tissue applicability, outperforming the [14C]biotin/bentonite method in specific organs.
• The radioimmunoassay offers a valuable tool for avidin research and diagnostics in avian biology.