Alanine racemase This protein is dimeric, but only one subunit is shown. The N-terminus is green. At residues 13-14 (red) it goes to form the yellow domain. At residues 242-243 (red) it comes back to finish the green domain.
Shaw, J. P., Petsko, G. A., Ringe, D.: Determination of the structure of alanine racemase from Bacillus stearothermophilus at 1.9-A resolution. Biochemistry 36 pp. 1329 (1997)
(PubMed)