Summary
A group of enzymes metabolizing amino acids have been investigated in Novikoff hepatoma tissue and in the livers of the same animals.
Novikoff hepatoma did not contain the following enzyme systems: tryptophan peroxidase-oxidase, tyrosine transaminase, phenylalanine hydroxylase, threonine dehydrase, serine dehydrase cystein desulfhydrase, histidase, and p-hydroxyphenylpyruvic acid oxidase.
Tryptophan peroxidase-oxidase, tyrosine transaminase, and threonine dehydrase could not be induced in these tumors by the administration of the respective substrates.
Novikoff hepatoma contained less glutamine synthetase and less arginase than did normal or adjacent liver and about 4 times as much aspartic acid transcarbamylase as did the adjacent liver.
These results are discussed in terms of the metabolic characteristics of the tumor and in terms of the “deletion hypothesis” of carcinogenesis.
This investigation was supported in part by research grant CY-3258 from the National Institute of Health and by an institutional grant from the American Cancer Society.
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