This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Schreiber, J. R. Articles by Pedersen, P. L. Search for Related Content PubMed PubMed Citation Articles by Schreiber, J. R. Articles by Pedersen, P. L.

Enzymatic and Spectral Analysis of Cytochrome Oxidase in Adult and Fetal Rat Liver and Morris Hepatoma 3924A¹

Department of Physiological Chemistry, Johns Hopkins School of Medicine, Baltimore, Maryland 21205 [J. R. S., W. X. B., P. L. P.], and Department of Biochemistry, Howard University School of Medicine, Washington, D. C. 20001 [H. P. M.]

Cytochrome oxidase, when measured either spectrally as cytochrome a and a₃ or polarographically by following the enzymatic oxidation of reduced cytochrome c, was about 60% lower in whole-cell suspensions of Morris hepatoma 3924A than in whole-cell suspensions of normal or host rat liver. Fetal liver, which has a maturation time very near that of the 3924A hepatoma, had a cytochrome oxidase activity about 50% lower than control liver. The cytochrome oxidase content of mitochondria isolated from the tumor cells was significantly higher than that of control liver mitochondria by use of either the spectral or polarographic assay method. Thus, the marked deficiency of cytochrome oxidase in the 3924A tumor cells could be ascribed most easily to a low mitochondrial content in the cell rather than to a reduced or impaired terminal cytochrome system in mitochondria. The compatability of the spectral and polarographic assay methods for assessing the relative amounts of cytochrome oxidase in normal and neoplastic tissue are clearly demonstrated by this study.

¹ This investigation was supported in part by USPHS Research Grants CA 10951-01 and CA 10729-01 and by an Institutional Grant to the Johns Hopkins School of Medicine from the American Cancer Society.

² Research Career Development Awardee, USPHS, National Cancer Institute, No. 1-K4-CA-23, 333.

Received 12/ 1/69. Accepted 6/16/70.