Crystallization and crystallographic analysis of the apo form of the orange protein (ORP) from Desulfovibrio gigas

The orange-coloured protein (ORP) from Desulfovibrio gigas is a 12 kDa protein that contains a novel mixed-metal sulfide cluster of the type [S₂MoS₂­CuS₂MoS₂]. Diffracting crystals of the apo form of ORP have been obtained. Data have been collected for the apo form of ORP to 2.25 Å resolution in-house and to beyond 2.0 Å resolution at ESRF, Grenoble. The crystals belonged to a trigonal space group, with unit-cell parameters a = 43, b = 43, c = 106 Å.