Isolation of a novel deoxyribonuclease with antifungal activity from Asparagus officinalis seeds

A deoxyribonuclease distinct from the previously isolated asparagus ribosom e-inactivating proteins, possessing a molecular weight of 30 kDa and requir ing a pH of 7.5 for optimum hydrolytic activity toward herring sperm DNA, w as isolated from Asparagus officinalis seeds. The isolation procedure invol ved extraction with saline, (NH,,),SO, precipitation, ion-exchange chromato graphy on DEAE-cellulose, affinity chromatography on Affi-gel blue gel, ion -exchange chromatography on CM-Sepharose, and FPLC gel filtration on Superd ex 75, The doxyribonuclease was unadsorbed onto DEAE- cellulose and Affi-ge l blue gel and adsorbed onto CM-Sepharose. It exhibited the novel N-termina l sequence, GIEVIKIREL. The deoxyribonuclease was purified to a specific ac tivity of 1584 units/mg. It was devoid of ribonuclease, protease, and HIV-1 reverse transcriptase-inhibitory activities. However, it inhibited cell-fr ee translation in a rabbit reticulocyte lysate system with an IC50 of 20 mu M. It exhibited antifungal activity toward Botrytis cinerea but not toward Fusarium oxysporum and Mycosphaerella arachidicola. (C) 2001 Academic Press .