A glyceraldehyde 3-phosphate dehydrogenase-inactivating factor has been isolated from the 105,000 × g supernatant solution of Ehrlich ascites tumor cells. This factor was purified 35-fold by steps that include the following: (NH4)2SO4 fractionation; freezing, thawing, and dialysis at 37°; and, finally, filtration chromatography through Sephadex G-100. The factor had a maximum absorption at 280 mµ, was not dialyzable, was heat labile, and could be precipitated by 10% trichloroacetic acid. The factor had no detectable proteolytic activity with denatured hemoglobin or α-benzoyl-dl-arginine-p-nitroanilide and was not affected by N-ethylmaleimide or soybean trypsin inhibitor. Excess NAD+ was required for complete protection of purified Ehrlich ascites tumor glyceraldehyde 3-phosphate dehydrogenase from inactivation by factor. Glyceraldehyde 3-phosphate dehydrogenase purified from rabbit muscle, Ehrlich ascites cells, mouse muscle, and yeast showed significantly different sensitivities to inactivation by factor.


This work was supported by National Cancer Institute Grant CA 08748 and American Cancer Society Grant T-431M.

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