GlucaGen (glucagon [rDNA origin] for injection) is an antihypoglycemic agent and a gastrointestinal motility inhibitor. It is produced by expression of recombinant DNA in a Saccharomyces cerevisiae vector with subsequent purification. The chemical structure of the glucagon in GlucaGen is identical to human glucagon and to glucagon extracted from beef and pork pancreas. Glucagon with the empirical formula of C153H225N43O49S, and a molecular weight of 3483, is a single-chain polypeptide containing 29 amino acid residues. The structure of glucagon is: