Gene duplication has long been considered a prerequisite for evolution of function, for a duplicate copy of a given gene is freed from normal functional and regulatory constraints allowing novel mutations to accumulate. Our studies focus on the biological role(s) that duplicate copies of GTP cyclohydrolase II proteins play in bacteria. Previous studies in our lab with Streptomyces coelicolor, an organism that harbors three GCH II orfs, have shown that these proteins are likely involved in different biosynthetic pathways, and that Streptomyces has utilized the GCH II scaffold to evolve a new catalytic function. This poster will show how bioinformatic and biochemical tools have been utilized to uncover and analyze the biological significance of similar duplication events in other organisms. This research is supported (in part) by a Career Award in the Biomedical Sciences from the Burroughs Wellcome Fund (V. B.). Additional support from NIH (GM 72623) is gratefully acknowledged.