Purification and partial characterization of an antibacterial protein LCIII.

Total proteins were precipitated by (NH4)2SO4 from the overnight culture supernatant of antagonistic bacterium Bacillus subtilis A014, applied to CM52 column and separated into three main peaks. The preparation of peak III showed to inhibit specifically the growth of rice bacterial blight pathogen Xanthomonas compestris pv. oryzea was further purified with Mono S column on FPLC and named antibacterial protein LCIII. The molecular weight of this protein is 26915Da, pI = 9.12. Analysis of amino acid composition was revealed to be rich in glycine, threonine and serine, and devoid of proline. Twenty-eight amino acids of N-terminal were sequenced by the Edman degradation and computer analysis of this partial sequence showed that antibacterial protein LCIII is a novel one.