The proteins and azoproteins of liver nuclei isolated in aqueous or nonaqueous medium from livers of rats fed the hepatocarcinogen 3′-methyl-4-dimethylaminoazobenzene for 20 days were compared. The two types of nuclear preparation apparently contained similar quantities of saline-soluble and -insoluble protein-bound azo dyes. In aqueous nuclei, the protein-bound dyes represent only 3% of those in liver, were 86% saline-soluble, and were present at a concentration (per mg protein) 43% that in cytoplasm. One-half of the proteins of both nuclei were saline-soluble and were similar according to free boundary and column zonal electrophoresis. In contrast to the situation with aqueous nuclei, which contain sizeable amounts of the specific soluble azoproteins, little of these slow h2-like azoproteins were found in the nonaqueous nuclei. The possible basis of this difference is discussed.

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This investigation was supported in part by USPHS Grants No. CA-05945, CA-06927, and FR-05539 from the National Cancer Institute, an appropriation from the Commonwealth of Pennsylvania, and a grant from the Deutsche Forschungsgemeinschaft, Bad Godesberg, Germany.

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©1969 American Association for Cancer Research.
1969
Cancer Research, Inc.