A molecular weight study of adenosine deaminase.

Adenosine deaminase exists in its smallest molecular form (ADA-S) of < 42 kDa in primate and rodent brain, intestine and liver, human erythrocytes, avian liver and in bovine spleen and intestine. The enzyme exhibits molecular heterogeneity in monkey and chicken liver and human erythrocytes. The large form of adenosine deaminase is seen in monkey liver and intermediary forms of the enzyme in chicken liver and human erythrocytes. Large forms of the enzyme predominate in rabbit intestine. Molecular weights of adenosine deaminase molecular forms were determined by gel filtration and by non denaturing gel electrophoresis with construction of Ferguson plots. Anomalous migration of the enzyme on SDS-PAGE possibly due to charge, disulfide bonds and proline content, did not allow for molecular weight determination on denaturing gels.