A simple phase-extraction assay for chloramphenicol acyltransferase activity

Area of Science:

• Biochemistry
• Molecular Biology
• Enzymology

Background:

• Chloramphenicol acetyltransferase (CAT) is a crucial reporter enzyme in molecular biology.
• Existing assays for CAT activity can be complex, costly, and lack sensitivity.
• A need exists for a more accessible and efficient method to quantify CAT activity.

Purpose of the Study:

• To develop a simple, sensitive, and cost-effective phase extraction assay for chloramphenicol (Cm) acetyltransferase (CAT) activity.
• To adapt the assay for diverse biological systems including mammalian cells, plant protoplasts, and cell culture supernatants.
• To enhance the assay's sensitivity through optimized substrate purification.

Main Methods:

• Enzymatic butyrylation of radiolabelled chloramphenicol (Cm) for phase extraction.
• Adaptation of the assay for various sample types (mammalian cells, plant protoplasts, supernatants).
• Development of a pre-extraction procedure for radiolabelled Cm purification.

Main Results:

• The developed CAT assay demonstrates linearity over 2-3 orders of magnitude of enzyme concentration.
• The assay is highly sensitive and significantly less expensive than current alternatives.
• The pre-extraction method increases sensitivity by 25-fold when using tritiated substrates.

Conclusions:

• A convenient and efficient phase extraction assay for CAT activity has been successfully developed.
• The assay is versatile and applicable to various organisms and sample types.
• This method provides a valuable tool for researchers studying gene expression and enzyme kinetics.