Characteristics of cold-adaptive endochitinase from Antarctic bacterium Sanguibacter antarcticus KOPRI 21702

The psychrotrophic Sanguibacter antarcticus KOPRI 21702^T, isolated from Antarctic seawater, produced a cold-adapted chitinolytic enzyme that is a new 55 kDa family 18 chitinase (Chi21702). Chi21702 exhibited high activities toward pNP-(GlcNAc)₂ and pNP-(GlcNAc)₃ with no activity for pNP-GlcNAc, indicating that it prefers chitin chains longer than dimers, just as endochitinases do. A mixture of GlcNAc and GlcNAc₂ was produced as a main product by Chi21702 activity from chitin oligosaccharides and swollen chitin, while less GlcNAc₃ was produced. These results show that Chi21702 has an endochitinase activity, randomly hydrolyzing chitin at internal sites. Chi21702 displayed chitinase activity at 0–40 °C (optimal temperature of 37 °C), maintained its activity at pH 4–11 (optimal pH of 7.6). Interestingly, Chi21702 exhibited relative activities of 40% and 60% at 0 and 10 °C, respectively, in comparison to 100% at 37 °C, which is higher than those of the previously characterized, cold-adapted, chitinases from bacterial strains.