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The Scientific World Journal
Volume 2014 (2014), Article ID 186029, 14 pages
Research Article

Molecular Phylogeny and Predicted 3D Structure of Plant beta-D- -Acetylhexosaminidase

1Department of Biochemistry and Molecular Biology, University of Rajshahi, Rajshahi 6205, Bangladesh
2Genetic Engineering Laboratory, Department of Molecular Biology, Faculty of Resource Science and Technology, Universiti Malaysia Sarawak, 94300 Kota Samarahan, Sarawak, Malaysia

Received 2 February 2014; Revised 14 June 2014; Accepted 21 June 2014; Published 20 July 2014

Academic Editor: Xiu-feng Wan

Copyright © 2014 Md. Anowar Hossain and Hairul Azman Roslan. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


beta-D- -Acetylhexosaminidase, a family 20 glycosyl hydrolase, catalyzes the removal of -1,4-linked -acetylhexosamine residues from oligosaccharides and their conjugates. We constructed phylogenetic tree of -hexosaminidases to analyze the evolutionary history and predicted functions of plant hexosaminidases. Phylogenetic analysis reveals the complex history of evolution of plant -hexosaminidase that can be described by gene duplication events. The 3D structure of tomato -hexosaminidase ( -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 ( / )8 barrel in the central part. The and 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 -Hex-Sl mutagenesis experiments for exploring the functions of this class of enzymes in plant kingdom.