GNAT is an open source, platform-independent MATLAB based toolbox. It is written in MATLAB and Java. It has been tested in Windows (Windows 7), Linux (Ubuntu), and Mac OS (X Lion) platforms.
The original GNAT package (file GNAT.zip) provides functions for reading, writing, manipulation, visualization and simulation of glycan structures and glycosylation reaction networks (citation ).
The second version of this software (GNATv2beta.zip) upgrades the original GNAT program with additional features that are geared towards incorporating glycan-structure experimental data into the simulation environment.
For information about GNAT installation and usage, please see the GettingStarted.pdf file enclosed in the package.
To cite GNAT:
 Gang Liu, Apurv Puri and Sriram Neelamegham, Glycosylation Network Analysis Toolbox (GNAT): a MATLAB based environment for systems glycobiology, Bioinformatics 2013 29: 404-406
gnatmatlab works perfectly, thanks