Activities of various hydrolytic
enzymes were determined in rat organ homogenates and on the surface of cells from various sources, i.e.,
tumor cell strains, primary cultured cells, normal cells, and their transformants.
Alanine,
leucine,
methionine,
phenylalanine, and glycyl-
proline aminopeptidases and
esterase showed relatively high activities in all these organs and cells. In the kidney homogenate the
aminopeptidase A activity was higher in other organs; i.e., the
aminopeptidase A activity was lower than that of
aminopeptidase B. Normal cells derived from kidneys showed the kidney-type pattern of amino-
peptidases A and B on the surface of cells, whereas
tumor cells from various origins were of another organ type. When cultured mouse fibroblast strain C3H2K and rat fibroblast strain 3Y1 cells were transformed by SV40 or by a ts A mutant and maintained at permissive temperature,
aminopeptidase A activity was drastically decreased, and the ratio of
aminopeptidase A to
aminopeptidase B was reduced to the levels of
tumor cells. If the ts A mutant-transformed cells were grown at the restrictive temperature, the ratio approached that of normal cells. In normal cells, however, cultivation at high or low temperature did not cause any change of the activities.