An Optimized Enzyme-Coupled Spectrophotometric Method for Measuring Pyruvate Kinase Kinetics

Area of Science:

• Biochemistry
• Molecular Biology
• Cancer Metabolism

Background:

• Pyruvate kinase M2 (PKM2) is a crucial glycolytic enzyme regulating cellular energy and biosynthesis.
• PKM2's unique allosteric regulation and nuclear functions are vital for cancer cell proliferation and the Warburg effect.
• Understanding PKM2's enzymatic activity is key to developing targeted cancer therapies.

Purpose of the Study:

• To establish a robust and reproducible protocol for the expression, purification, and enzymatic characterization of Pyruvate Kinase M2 (PKM2).
• To provide a reliable method for analyzing PKM2 kinetics, regulation, and potential therapeutic modulation in cancer research.

Main Methods:

• Recombinant wild-type PKM2 was expressed in *E. coli* and purified using Ni-NTA affinity and size-exclusion chromatography.
• Enzymatic activity was assessed using a non-radioactive, lactate dehydrogenase (LDH)-coupled spectrophotometric assay monitoring NADH consumption at 340 nm.
• Kinetic analyses were performed under varying conditions, including substrate concentrations, pH, and the presence of fructose-1,6-bisphosphate (FBP).

Main Results:

• The protocol yields high-purity, properly folded PKM2 suitable for biochemical and structural studies.
• The LDH-coupled assay provides sensitive, real-time kinetic measurements of PKM2 activity.
• The method effectively characterizes PKM2 regulation by FBP and allows for analysis of different pH conditions.

Conclusions:

• This optimized protocol enables comprehensive functional studies of PKM2, including its regulation and enzymatic properties.
• The developed method is valuable for investigating PKM2 variants, post-translational modifications, and for screening potential cancer therapeutics.
• This research provides a critical tool for advancing the understanding of PKM2's role in cancer metabolism and progression.