Abstract: The nucleic sequence of Glutamic acid decarboxylase 2(GAD2) was cloned, sequenced using RT-PCR method and DNA sequencing techniques. Then the molecular model of three-dimensional structure of the predicted mature protein was constructed. The results revealed that the GAD2 gene was consistently 1758bp in length, encoding for a predicted polypeptide of 585 amino acid residues, including a pyridoxal-5?-phosphate (PLP). Multiple alignments were used to establish the primary structure homology for 19 glutamate decarboxylases of different origin, to design a phylogenetic tree, These data allowed us to elucidate the paths of divergent and convergent evolution of the enzyme.