Phosphodiesterase I

Purified by the method of Williams, Sung and Laskowski, J. Biol. Chem., 236, 1130 (1961). Further treated to inactivate contaminating 5'-nucleotidase activity according to Sulkowski and Laskowski: Biochim. Biophys. Acta, 240, 443 (1961). Lyophilized in vials.