Starting with oligopeptide sequences and using PCR, the gene of the cyclodextrinase fromFlavobacteriumsp. no. 92 wasderivedfrom sequenced and expressed inEscherichia coli; the gene pro-duct was purified and crystallized. An X-ray diffraction analysis using seleno-methionines with multiwavelength anomalous diffraction techniques yielded the refined 3D structure at A ˚ resolution.