CRYSTALLIZATION OF CYTOCHROME B(562) FROM ERWINIA-CHRYSANTHEMI

Cytochrome b(562) from Erwinia chrysanthemi has been crystallized usin g the hanging-drop vapour-diffusion method with ammonium sulfate as th e precipitant. X-ray precession photographs show that the crystals for med belong to either of the enantiomorphic space groups P4(1)2(1)2 or P4(3)2(1)2 with the cell parameters a = b = 98.6 and c = 62.7 Angstrom . Estimation of the crystal density and consideration of the possible values for V-m indicate that there is either a dimer or trimer in the asymmetric unit. Experiments using the synchrotron radiation source at the CCLRC Daresbury Laboratory have shown that the crystals diffract to at least 2.7 Angstrom resolution. An analysis of the N-terminal seq uence indicates that this cytochrome shows limited homology to the cyt ochrome b(562) from E. coli. Determination of the structure will there fore allow analysis of the relationship between these two proteins.