10.22376/ijpbs.2019.10.1.p1-12 Volume 2 Issue 4 2011 (October - December) Proteins are macromolecules with a characteristic sequence of amino acid linked by peptide bond and play a vital role in metabolic pathways. There are 20 major amino acids and hundreds of "minor amino acids" - some are short-lived and some are the modifications of the main 20. Tryptophan synthase, in the biosynthetic pathway of the aromatic amino acid Tryptophan is regulated by the "trp operon" in E.coli. Tryptophan: In the lessThan i greaterThan Shikimic acid pathway lessThan /i greaterThan , Chorismate is a key intermediate in the biosynthesis leading to the formation of the aromatic amino acids ( lessThan i greaterThan phenylalanine, tyrosine and tryptophan lessThan /i greaterThan ). lessThan i greaterThan Tryptophan Synthase lessThan /i greaterThan is a bifunctional, bienzyme complex having two α chains and two β chains that forms the a lessThan sub greaterThan 2 lessThan /sub greaterThan b lessThan sub greaterThan 2 lessThan /sub greaterThan tetrameric enzyme complex. In most of the organisms α chain is encoded by the gene trpA and β chain is encoded by the gene trpB. lessThan i greaterThan Salmonella typhimurium lessThan /i greaterThan was taken as a reference organism for comparative genomics of Tryptophan synthase and data that was available for comparative genomics was interrogated with bioinformatics tools. The amino acid (aa) sequence of tryptophan synthase beta chain of lessThan i greaterThan Salmonella typhimurium lessThan /i greaterThan from the PDB was taken as the standard sequence and pair-wise alignments and multiple sequence alignment was pursued for all the 41 proteobacteria using BLAST 2 programme and Clustal X (1.83). phylogenitic analysis was drawn by using tree view. Satpal Singh Bisht, Santosh Kumar Behera, Amrita Panda And B.Praveen. Salmonella typhimurium, Proteobacteria, PDB (Protein Data Bank), Tryptophan synthase, Bioinformatics 279-284