A rapid enzyme assay for beta-galactosidase using optically gated sample introduction on a microfabricated chip

Area of Science:

• Biochemistry
• Analytical Chemistry
• Microfluidics

Background:

• Enzyme assays are crucial for biochemical research and drug discovery.
• Traditional methods like plate assays can suffer from fluorescence interference and require large sample volumes.
• Microfluidic devices offer potential for miniaturized and more efficient assays.

Purpose of the Study:

• To demonstrate enzyme assays on microchips using optically gated sample introduction.
• To analyze the kinetics and inhibition of beta-galactosidase (beta-Gal).
• To compare microchip assay performance against traditional methods.

Main Methods:

• Utilized microchips with optically gated sample introduction for continuous monitoring.
• Performed serial on-chip separations of fluorescein mono-beta-d-galactopyranoside (FMG) and fluorescein.
• Assayed beta-Gal from bovine liver and E. coli, and studied inhibition by PETG and beta-lactose.

Main Results:

• Successfully obtained kinetic information for beta-Gal by varying FMG concentration.
• Demonstrated the technique's ability to compare enzyme sources and inhibition effects.
• Achieved significantly lower enzyme and substrate requirements (four orders of magnitude less) compared to traditional assays.

Conclusions:

• Optically gated microchip assays provide a sensitive and interference-free method for enzyme analysis.
• The technique is suitable for continuous monitoring and high-throughput screening.
• This microfluidic approach is valuable for drug discovery and enzyme characterization.