A comparative study of aldolase from human muscle and liver

Aldolase was purified from human skeletal muscle and human liver by techniques capable of processing large quantities (10-20kg) of tissue. The methods used also proved convenient for isolating aldolase on a large scale from other mammalian and avian sources. Aldolase from both human liver and muscle was crystallized; each gave two crystalline forms, depending on the conditions of crystallization. X-ray studies on the muscle aldolase crystals suggest a close structural similarity between human and rabbit muscle aldolase. Aldolases from human muscle and liver have similar pH optima and pH stability but their stability to heat treatment differs. The effect of heat on the enzymes may therefore provide an easy means of distinguishing them. The kinetic constants K(m) and k(cat.) for these aldolases are similar to other mammalian aldolases. Amino acid analyses and tryptic peptide ;mapping' show that the primary structures of the two aldolases differ greatly.