Crystallization and preliminary X-ray analysis of βC–S lyases from two oral streptococci

Hydrogen sulfide, which causes oral malodour, is generally produced from l-cysteine by the action of βC–S lyase from oral bacteria. The βC–S lyases from two oral bacteria, Streptococcus anginosus and S. gordonii, have been cloned, overproduced, purified and crystallized. X-ray diffraction data were collected from the two types of crystals using synchrotron radiation. The crystal of S. anginosusβC–S lyase belonged to the orthorhombic space group P2₁2₁2₁, with unit-cell parameters a = 67.0, b = 111.1, c = 216.4 Å, and the crystal of S. gordoniiβC–S lyase belonged to the same space group, with unit-cell parameters a = 58.0, b = 73.9. c = 187.6 Å. The structures of the βC–S lyases were solved by molecular-replacement techniques.