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 Blocker, R. Articles by Roth, J. S. Search for Related Content PubMed PubMed Citation Articles by Blocker, R. Articles by Roth, J. S.

Factors Affecting Deoxycytidylate Deaminase Activity in Some Transplantable Rat Hepatomas¹

Section of Biochemistry and Biophysics, Biological Sciences Group, The University of Connecticut, Storrs, Connecticut 06268

Dunning hepatoma has a low activity of deoxycytidylate deaminase, comparable to that of normal adult rat liver. This activity seems inconsistent with the rapid proliferation rate of the tumor. Factors which might affect the activity of deoxycytidylate deaminase in the Dunning hepatoma have been examined in it and compared to the Novikoff hepatoma which has high activity of this enzyme.

The low activity in Dunning hepatoma does not appear to be the result of any inhibition or, possibly, proteolytic enzyme as judged by mixing experiments, nor does it appear to be due to in vivo differences in nucleotide concentrations especially deoxycytidine 5'-monophosphate, deoxycytidine 5'-triphosphate, or deoxyguanosine 5'-monophosphate which might either help stabilize the enzyme, allosterically increase its activity, or inhibit it.

The Dunning hepatoma does not convert cytosine deoxyriboside to uridine deoxyriboside at a significant rate, and the formation of uridine deoxyriboside from deoxyuridine monophosphate is 1% or less during a 30-min incubation of high-speed supernatant fraction from the tumor in either the presence or absence of fluoride.

It is concluded that the Dunning hepatoma probably has intrinsically low deoxycytidylate deaminase activity.

¹ This research was supported by grants from the Damon Runyon Memorial Cancer Fund, The National Cancer Institute Grant CA-06384, and American Cancer Society Grant P-303.

² Recipient of Career Award RC31-63 from the National Cancer Institute, NIH.

Received 7/28/76. Accepted 2/16/77.