Subunit interactions and catalytic activity of triose phosphate isomerase

Rabbit and chicken triose phosphate isomerase were labelled with iodo-(1-14C)-acetamide. The efficiencies of renaturation after denaturation in guanidinium chloride were similar to those of the unlabelled enzymes. The enzymes were immobilised to Sepharose 4B and after guanidinium treatment only immobilised monomers remained on the gel. Hybridisation studies demonstrated that the dimeric form could be reformed on the denatured gels with recovery of the original specific activity. Under similar conditions formation of rabbit-chicken dimers were observed. However, competition studies demonstrated a preferential formation of the homogeneous dimers.