Triethylaminoethyl cellulose column chromatography was used to separate the multiple forms of aminopeptidase and arylamidase from human normal and cancer tissues.
Aminopeptidase and arylamidase from normal liver were separated into three fractions: Li.I, Li.II, and Li.III. The activity of Li.III, which showed very low values in normal liver, increased remarkably in hepatic cancer. Normal stomach contained three fractions: S.I, S.II, and S.III. Stomach cancer contained an additional fraction, S.IV, between S.I and S.II. Normal lung contained four fractions: Lu.I, Lu.II, Lu.III, and Lu.IV. Lung cancer contained three fractions, Lu.II being absent. On the other hand, normal kidney, small intestine, and serum had only one major fraction (K.II, S.In.I, and Se.I, respectively).
Immunological studies using antibodies of purified Li.I and Li.II showed that the antigenicities of Li.I and Li.II were different, and aminopeptidases and arylamidases in normal and cancer tissues were classified into three immunologically different types: Li.I type (Li.I, S.I, and Lu.I), Li.II type (Li.II, Li.III, S.II, S.IV, Lu.II, Lu.III, Lu.III′, K.II, S.In.I, and Se.I), and the third type (S.III and Lu.IV).
After neuraminidase treatment, Li.II, Li.III, S.II, Lu.III, Lu.III′, and Se.I of Li.II type were eluted in the position of S.IV, Lu.II, and K.II on triethylaminoethyl cellulose column chromatography. However, the elution positions of the Li.I type and the third type were not affected by neuraminidase treatment.
From these results, it was suggested that the difference between the column patterns in normal and cancer tissues was due to the amount of sialic acid present in the enzyme molecule.
This work was supported in part by a research grant for Cancer Research from the Ministry of Welfare of Japan.