Terminal deoxynucleotidyl transferase in rooster sperm

A 165,000g pellet fraction, isolated from lysed rooster spermatozoa, was shown to contain a deoxynucleotide polymerizing activity which banded in sucrose at a buoyant density of 1.15gm/ml. The solubilized enzyme, partially purified by gel filtration, was estimated to have a molecular weight of 33,000 and utilized dT10 or dG10 as exogenous primers in template-independent reactions sensitive to either sodium pyrophosphate or ethylenediaminetetra- cetic acid. Pyrimidine nucleotides (dTTP) were preferentially polymerized in the presence of Co++, while purine nucleotides (dGTP) were the preferred substrate when Mn++ was the divalent cation. These properties are all consistent with those of terminal deoxynucleotidyl transferase. An enzyme with similar properties was also obtained by subjecting a rooster sperm lysate to the procedure utilized to isolate terminal deoxynucleotidyl transferase from calf thymus. It is hypothesized that the enzyme may be involved in the regulation of gene expression during embryogenesis.