Crystal structure study of Opsanus tau parvalbumin by multiwavelength anomalous diffraction

Abstract

The crystal structure of a small calcium‐binding protein, the parvalbumin III_f from Opsanus tau in which Tb was substituted for Ca, has been analysed by multiwavelength anomalous diffraction. Data at a resolution of 2.3 Å were collected at three wavelengths near the L₃ absorption edge of Tb (1.645–1.650 Å), using the synchrotron radiation emitted by a storage ring and a multiwire proportional counter. The phases of the reflections were determined from this single derivative, without native data. Prior to any refinement, the resulting electron density map shows a good agreement with the model of the homologous carp parvalbumin in regions of identical amino‐acid sequence.