The broad-specificity chitinases: their origin, characterization, and potential application

Chitinases are hydrolases that catalyze the cleavage of the β-1,4-O-glycosidic linkages in chitin, a polysaccharide abundantly found in nature. Although numerous chitinolytic enzymes have been studied in detail, relatively little is known about chitinases capable of broad specificity. Broad-specificity chitinases are a sort of novel chitinases possessing two or three different catalytic activities among exochitinase, endochitinase, and N-acetylglucosaminidase. In the light of the difference of module composition and catalytic mechanism, the broad-specificity chitinases included two broad categories, broad-specificity chitinases with a single catalytic domain or multi-catalytic domains. This broad-specificity chitinases have great potential in chitin conversion. In this review, we summarize all reported cases of broad-specificity chitinases and provide an overview of the recent findings on their origin, characterization, catalytic mechanism, and potential application. Moreover, in-depth study into these chitinases could contribute to our understanding of other broad-specificity enzymes which may have some benefits on progress of biotechnology.