DMSO REDUCTASE FROM RHODOBACTER CAPSULATUS. A. S. McAlpine, S. Bailey, CCLRC Daresbury Laboratories, Daresbury, Warrington, WA4 4AD, Cheshire, England

DMSO reductase from the photosynthetic bacteria Rhodobacter capsulatus has been crystallised in two forms which are suitable for X-ray structure determination. DMSO reductase from Rhodobacter is the simplest molybdenum oxotransferase known and as a result makes it an ideal model to study the structure and function of this class of enzymes.

Both crystal forms belong to the same space group, P 4₁2₁2 and have cell dimensions a = b = 80.81 Å c = 229.75 Å (type I) and a = b = 89.30 Å, c = 230.05 Å (type II). Data have been collected from crystal type I at both room temperature and at 100K.

Several heavy atom derivatives have been collected leading to poor MIR phases. Density modification has improved the electron density maps and interpretation of these maps is underway.