Inhibition of deoxynucleotide-polymerizing enzyme activities of human cells and of simian sarcoma virus by heparin
DiCioccio, R.A.; Srivastava, B.I.
Cancer Research 38(8): 2401-2407
1978
ISSN/ISBN: 0008-5472 PMID: 78759 Document Number: 129126
Heparin [a potential anti-cancer agent] inhibited the activities of: reverse transcriptase from simian sarcoma virus; DNA polymerases .alpha., .beta. and .gamma. from phytohemagglutinin-stimulated normal human lymphocytes, human leukemic lymphoblasts and Molt-4 cells which are of acute lymphoblastic leukemia origin; and terminal deoxynucleotidyl transferase from the 2 latter cell types. A 10-fold excess of enzyme overcame heparin inhibition of DNA polymerase .alpha., .beta. and .gamma. activities but not of simian sarcoma virus reverse transcriptase or terminal deoxynucleotidyl transferase activities. Heparin inhibition of all enzyme activities examined was partially surmounted by additional template primer or initiator, but additional deoxyribonucleoside 5'-triphosphate, bovine serum albumin or divalent cation had virtually no effect on heparin inhibition. The degree of inhibition of each enzyme by heparin was independent of time, and addition of heparin to assay mixtures after the start of a reaction immediately inhibited each enzyme activity. Each enzyme was bound to a heparin-Sepharose 4B chromatography column and was eluted between 0.2-0.4 M NaCl. DNA polymerases .alpha. and .gamma. from the cellular soluble fraction and terminal deoxynucleotidyl transferase and DNA polymerases .beta. and .gamma. from the chromatin fraction were purified 9.6-71.2-, 3.2-, 2.3- and 3.3-fold, respectively, by the above chromatography procedure. Heparin inhibited all the enzyme activities studied by reversibly binding to each enzyme, thereby interfering with the interaction of template primer or initiator with enzyme.