A HUMAN ERYTHROCYTE-DERIVED GROWTH-PROMOTING FACTOR WITH A WIDE TARGET-CELL SPECTRUM - IDENTIFICATION AS CATALASE

We have reported previously that a factor with a molecular weight of 5 3,000 under SDS-polyacrylamide gel electrophoresis purified from human erythrocyte extracts promoted the growth of a wide variety of cell ty pes from different species, including T cells, B cells, myeloid leukem ia cells, melanoma cells, and mastocytoma cells, as well as normal and transformed fibroblast cells. In the present study, amino acid sequen ce analysis revealed that this factor has homology with human catalase . The purified factor exhibited catalase activity. Catalases derived f rom human erythrocytes, bovine liver, Aspergillus niger, and recombina nt rat liver catalase are all able to promote the growth of cells. Ant ibody against human catalase absorbed both the growth-promoting activi ty and the enzyme activity of the purified factor. In addition, treatm ent of the factor with an irreversible enzyme inhibitor, aminotriazole , resulted in abrogation of both the growth-promoting activity and enz yme activity. These results indicate that the growth-promoting factor is catalase, and its activity is associated with the decomposition of hydrogen peroxide.