To investigate the changes of nucleic acid related compounds in oysters during frozen storage and thawing enzymes responsible for decomposition of nucleic acid and the relating substances were isolated and purified by using DEAE-cellulose and DEAE-sephadex column techniques. Four phosphomonoesterase fractions (A, B, C, D) with the optimal temperature of 40°C and optimal pH range of 4, 0 or 10, 0 were obtained.
Fraction C also contained activity with the optimal temperature of 40°C and optimal pH range of 3.5.
During frozen storage and thawing of oyster meat 5'-AMP and 5'-IMP seemed to be formed from nucleoside polyphosphate by the actions of PMase and DAase contained in the oyster meat.