beta-D- N -Acetylhexosaminidase, a family 20 glycosyl hydrolase, catalyzes the removal of β -1,4-linked N -acetylhexosamine residues from oligosaccharides and their conjugates. We constructed phylogenetic tree of β -hexosaminidases to analyze the evolutionary history and predicted functions of plant hexosaminidases. Phylogenetic analysis reveals the complex history of evolution of plant β -hexosaminidase that can be described by gene duplication events. The 3D structure of tomato β -hexosaminidase (β -Hex-Sl) was predicted by homology modeling using 1now as a template. Structural conformity studies of the best fit model showed that more than 98% of the residues lie inside the favoured and allowed regions where only 0.9% lie in the unfavourable region. Predicted 3D structure contains 531 amino acids residues with glycosyl hydrolase20b domain-I and glycosyl hydrolase20 superfamily domain-II including the (β / )8 barrel in the central part. The and β contents of the modeled structure were found to be 33.3% and 12.2%, respectively. Eleven amino acids were found to be involved in ligand-binding site; Asp(330) and Glu(331) could play important roles in enzyme-catalyzed reactions. The predicted model provides a structural framework that can act as a guide to develop a hypothesis for β -Hex-Sl mutagenesis experiments for exploring the functions of this class of enzymes in plant kingdom.
Hossain, M. A., & Roslan, H. A. (2014). Molecular phylogeny and predicted 3D structure of plant beta-D-N-acetylhexosaminidase. Scientific World Journal, 2014. https://doi.org/10.1155/2014/186029