Evaluation of the Effect of Glyceraldehyde 3-phosphate Dehydrogenase on Heat-induced Myofibril Gels by Investigating Actin-myosin Interaction

In this study, the effect of glyceraldehyde 3-phosphate dehydrogenase (G3PD) on the molecular state of porcine myofibrils was investigated by observing the structural changes in myosin and actin in myofibrils using phase-contrast and fluorescence microscopy. Though the myofibril gel strength was not influenced by G3PD at a G3PD to myofibril weight ratio (G/M ratio) of 1/20, the gel strength significantly increased at a G/M ratio ≥ 1/10. SDS-PAGE analysis demonstrated that myosin heavy chain band intensity increased in the myofibril soluble fraction by adding G3PD, suggesting G3PD facilitated the solubilization of myosin and actin. Phase-contrast microscopy also showed increased myofibril solubilization with increasing G3PD. Fluorescence microscopy revealed that G3PD colocalized with actin segments. Myosin segments also colocalized with actin segments in G3PD-treated myofibrils, suggesting myosin bound to actin. The addition of G3PD to myofibrils increased the Mg2+- and Mg2+-EGTA-ATPase activities, suggesting G3PD would not change the conformation of myofibrils.