A thaumatin-like antifungal protein from the emperor banana.

A 20-kDa protein with substantial N-terminal sequence homology to thaumatin-like proteins was isolated from ripe fruits of the emperor banana, Musa basjoo cv. 'emperor banana'. The isolation procedure entailed (NH(4))(2)SO(4) precipitation, ion exchange chromatography on DEAE-cellulose, and affinity chromatography on Affi-gel blue gel. The thaumatin-like protein inhibited mycelial growth in Fusarium oxysporum and Mycosphaerella arachidicola. However, it did not affect the mitogenic response of murine splenocytes or [methyl-(3)H] thymidine incorporation by tumor cells. The activity of HIV-1 reverse transcriptase was slightly inhibited.