Pyruvate kinase activity

The pyruvate kinase activity was measured using the PK enzyme activity assay kit (Sigma Aldrich, St Louis, MO) as per manufacturer's protocol. Briefly, cell extracts were prepared and assayed for PK activity using buffers provided by manufacturer. The absorbance at 570 nm was read using a EMax Plus spectrophotometer (Molecular Devices, Sunnyvale, CA). The protein activity was measured using a standard curve developed using the standards provided by manufacturer and activity quantitative expressed as units/mg protein.