The activity of deoxyribonucleic acid polymerase in some species of algae.

Abstract

1. The activities of DNA polymerase preparations from the algae Euglena gracilis, Chlamydomonas reinhardtii, Chlorella pyrenoidosa, Anabaena variabilis and Anacystis nidulans were measured. The blue-green algae Anabaena and Anacystis contain a 5-20-fold higher activity of the enzyme than do the green algae. DNA polymerases from the blue-green algae show a pH optimum of 9 and prefer a relatively low Mg(2+) concentration (1-3mm). DNA polymerases from the green algae, however, display a pH optimum between 7.5 and 8.5 and an optimum Mg(2+) concentration of 8mm. With all algae, a higher polymerase activity was obtained with denatured salmon sperm DNA as template than with native DNA. All four deoxyribonucleoside 5'-triphosphates must be present for full activity of the polymerases. 2. With one exception, the deoxyribonuclease activities in the preparations, measured under conditions of the DNA polymerase assay, are low compared with corresponding preparations from Escherichia coli. Chlamydomonas extracts contain a high deoxyribonuclease activity. 3. After purification on columns of DEAE-cellulose, the polymerase activity was linear over a wide range of protein concentrations, except for Chlamydomonas preparations, where the observed deviation from linearity was probably attributable to the high nuclease activity. 4. DNA polymerases from all these algae bind strongly to DNA-cellulose; 6-40-fold purifications of the enzyme were obtained by chromatography on columns of DNA-cellulose. 5. The partially purified polymerases of Euglena and Anacystis are heat-labile but become much more heat-stable when tested in the presence of DNA.