Effects of protein phosphorylation on lactate dehydrogenase activity glycolysis in postmortem Yanbian yellow cattle...

Phosphorylation of lactate dehydrogenase (LDH) influences postmortem muscle energy metabolism and meat maturation. This study investigated the regulatory mechanisms of LDH phosphorylation in bovine muscle. We employed mass spectrometry to map modification sites, molecular dynamics (MD) simulations to model conformational changes, and Fourier transform infrared spectroscopy (FTIR) to detect secondary structural shifts. Results showed that phosphorylation positively regulated LDH activity. Mass spectrometry identified significantly higher phosphorylation at key residues (Ser79, Ser301, Tyr247) in PKA-treated samples. Notably, these phosphorylation levels correlated strongly with increased enzymatic activity. Furthermore, MD simulations and FTIR analysis revealed that phosphorylation stabilizes the LDH structure by altering dihedral angles, strengthening hydrogen bonds, and regulating secondary structure components. Specifically, FTIR confirmed that phosphorylation decreased β-turn content and increased β-sheet and random coil contents, thereby enhancing structural stability and increasing the catalytic activity of lactate dehydrogenase. This study demonstrates that phosphorylation modulates postmortem glycolysis through dynamic regulation of LDH structure, offering insights for improving meat quality.