Figure 2. Structure of the double-labeled Escherichia coli DHFR with bound NADP+ (green) and folic acid (purple; PDB code 1rx2). The amino acids labeled with a fluorescent probe, amino acid 37, and a fluorescence energy acceptor, amino acid 17, are indicated. Also shown is amino acid 121; the mutation of this residue is discussed in the text. The figure was reproduced with permission from ref (27).
Free-Energy Landscape of Enzyme Catalysis
Stephen J. Benkovic, Gordon G. Hammes, and Sharon Hammes-Schiffer Biochemistry 2008;ASAP Article; DOI: 10.1021/bi800049z