Sodium carbonate versus borate buffer for lactase quenching, laboratory work

Area of Science:

• Biochemistry
• Enzymology
• Biocatalysis

Background:

• Enzyme assays are crucial for quantifying enzyme kinetics and activity.
• Continuous and quenched assay methods exist, each with specific applications and limitations.
• Effective quenching agents are vital for accurate endpoint determination in stopped assays.

Purpose of the Study:

• To compare the efficacy of sodium carbonate and borate buffer as quenching agents for lactase (β-galactosidase) in a continuous assay.
• To evaluate the performance of these quenching agents based on enzyme activity and rate constant determination.
• To provide advanced undergraduate students with hands-on experience in enzyme kinetics and high-throughput techniques.

Main Methods:

• A continuous enzyme assay was established using β-galactosidase (Aspergillus oryzae) and its substrate, 4-nitrophenyl β-D-galactopyranoside.
• The release of 4-nitrophenol was monitored using a microplate reader.
• Sodium carbonate and borate buffer were tested as quenching agents, with an unstopped assay serving as the control.

Main Results:

• Both sodium carbonate and borate buffer were assessed for their ability to terminate the enzymatic reaction.
• Enzyme activity and the rate constant (k) were calculated based on the amount of released 4-nitrophenol.
• The study enabled a comparative analysis of the quenching efficiency of the tested agents.

Conclusions:

• The experiment provided students with practical insights into enzyme assay methodologies and the selection of appropriate quenching agents.
• Borate buffer was identified as a potentially effective agent for quenching lactase activity in this continuous assay setup.
• The exercise fostered critical thinking, research-based learning, and familiarity with high-throughput techniques relevant to R&D.