Association of Glyceraldehyde‐3‐Phosphate Dehydrogenase with the Particulate Fraction of Chicken Skeletal Muscle

When chicken breast muscle was homogenized in water, approximately 86% of the glyceraldehyde-3-phosphate dehydrogenase was associated with the particulate fraction. The enzyme was solubilized by increasing pH with a very marked increase in the pH range of 6.9 to 7.1. At low ionic strength (about 0.015), approximately 50% of the enzyme is solubilized at pH 7.5 and above. Increasing ionic strength also led to increased solubilization. In addition, there was a specific cation effect with Ca2+ greater than Mg2+ greater than K+ greater than Na+ at a constant ionic strength. Glyceraldehyde 3-phosphate and 2,3-bisphosphoglycerate were effective in partially solubilizing the enzyme. Solubilized glyceraldehyde-3-phosphate dehydrogenase can rebind to the particulate fraction of the homogenized muscle. The soluble form of the enzyme has a higher V and a higher Km (glyceraldehyde-3-phosphate) than the enzyme bound to the particulate fraction.