Endochitinase 1 (Tv-ECH1) from Trichoderma virens has high subsite specificities for acetylated units when acting on chitosans

Chitosans with defined characteristics have been shown to possess reproducible bioactivities for numerous applications. A promising approach for producing chitosans with defined degrees of polymerization (DP), degrees of acetylation (DA), and patterns of acetylation (PA) involves using chitin-modifying enzymes. One such enzyme, the chitinase Tv-ECH1 belonging to the glycoside hydrolase (GH) family 18, seems to have an important role in the biocontrol properties of the fungus Trichoderma virens, suggesting its potential in generating novel chitosans for plant health applications. In this study, the Tv-ECH1 enzyme was overexpressed in the methylotrophic yeast Pichia pastoris, yielding large amounts (up to 2 mg mL−1) of purified recombinant enzyme of high activity, high purity, and high stability, making the system promising for industrial production of Tv-ECH1. The purified Tv-ECH1 chitinase displayed a wide optimal pH range from 4.5 to 6 and an optimal temperature of 37 °C. Detailed subsite specificity analyses revealed high preference for acetylated residues at all four subsites analyzed (−2, −1, +1, +2), making Tv-ECH1 a promising candidate for the biotechnological production of specific chitosan oligomers and for the characterization of chitosan polymers via enzymatic fingerprinting.