A quantitative stopped-flow fluorescence assay for measuring polymerase elongation rates

Area of Science:

• Biochemistry
• Molecular Biology
• Enzymology

Background:

• Traditional methods for measuring nucleic acid polymerase elongation rates are time-consuming and complex.
• Existing assays often involve radiolabeled substrates and multiple experimental steps.

Purpose of the Study:

• To introduce a novel, real-time stopped-flow assay for determining polymerase elongation kinetics.
• To provide an alternative to lengthy experimental procedures for kinetic parameter determination.

Main Methods:

• The assay utilizes a stopped-flow technique to measure the time taken for a polymerase to complete elongation on a defined template.
• It builds upon the PETE (polymerase elongation template element) assay, adapted for real-time kinetic measurements.
• Kinetic data is modeled as a series of irreversible steps to fit time-based datasets.

Main Results:

• The assay successfully determined Vmax rates and apparent Km values for nucleotide triphosphate (NTP) utilization using poliovirus polymerase.
• It accurately measures average elongation rates across heterogeneous template regions.
• Demonstrated applicability with RNA substrates and potential for DNA polymerases.

Conclusions:

• This real-time stopped-flow assay offers an efficient alternative for measuring polymerase elongation kinetics.
• The method is versatile, adaptable to various polymerases, and can handle complex template structures.
• It provides accurate kinetic parameters essential for understanding enzyme mechanisms.