Distinguishing between the active site and a nearby dicarboxylic acid binding site in Fumarase C
Background
In early studies of in "E. Coli", two carboxylic acid binding sites, subsequently named A- and B-, were observed in the wild type crystal structure. The structures of these two sites was considerably different as site A contained atoms of three of the four subunits of fumarase C whereas site B contained only atoms from a single subunit of the tetramer. However, it was heavily believed that the carboxylic acid binding site A- was the location of the fumarase active site but it could not be verified without first mutating both active sites in order to determine the activity of the reactions. Prior data had suggested that a was the critical base in the catalysis and therefore H188 (located in the A- site) and H129 (located in the B-site) were mutated to asparagines in the hopes that this residue mutagenesis would prompt a dramatic catalytic affect in the active site and minimal affect in the other carboxylic acid binding site.
Data
Weaver et. al.[1]
