Thermal Inactivation as a Means of Inhibiting the Serum-Associated Deamination of 9-β- d -Arabinofuranosyladenine in Tissue Culture Media

Abstract

9-β- d -Arabinofuranosyladenine (ara-A) was deaminated to 9-β- d -arabinofuranosylhypoxanthine by adenosine deaminase present in fetal bovine serum, newborn calf serum, and calf serum used to supplement tissue culture media. Heating newborn calf serum or calf serum for 12 h at 56 C completely eliminated the enzymatic deamination of ara-A. The deaminase activity associated with fetal bovine serum was more refractory to heating, requiring 24 h for complete inactivation. The nutritive value of heat-inactivated calf serum did not differ significantly from that of unheated serum based on considerations of population doubling times, deoxyribonucleic acid synthesis, and relative cloning efficiencies of KB cells.