Aminotripeptidase of swine kidney. II. Amino acid composition and molecular weight.

Three different forms of aminotripeptidase have been obtained from swine kidney. As studied in the ultracentrifuge by sedimentation-equilibrium, these forms are: 1. a stable monomer of 71,100 molecular weight that consists of a single polypeptide chain lacking disulfide bridges; 2. a stable dimer that contains two apparently identical subunits of the same size as the monomer; and 2’. an unstable dimer that dissociates spontaneously to the monomeric units during sedimentation-equilibrium studies at 20’. Aminotripeptidases-1 and -2 have the same amino acid composition.