Characterization of amylases produced by tumors

Amylases were purified and characterized from three amylase-producing human tumors. The relative molecular mass of the amylases was estimated to be 54 000 on sodium dodecyl sulfate/polyacrylamide gel electrophoresis, different from human salivary amylase (61 000 and 64 000) and human pancreatic amylase (60 000). The tumor amylases had completely identical antigenicities with human salivary and pancreatic amylases against antibody to human salivary amylase, while the intensity of the tumor amylases was less than 20% of that of human salivary and pancreatic amylases on single radial immunodiffusion. On isoelectric focusing, two of the three tumor amylases showed a major peak at pH 6.4, which corresponded to a major peak of human salivary amylase, the other showed a major peak at pH 6.4, which corresponded to a minor peak of human salivary amylase. The three tumor amylases showed similar amino acid composition, different from those of human salivary and pancreatic amylases. These findings suggest that tumor amylases have a tertiary structure similar to that of normal human amylases, but differ from them in amino acid composition.