Preliminary crystallographic analysis of a proteolytically modified form of E. coli single stranded DNA binding protein

A proteolytically modified form of the Escherichia coli single-stranded DNA-Binding protein (SSB) has been crystallized from 15% saturated sodium citrate. Crystals as large as 1.0 mm x 0.3 mm x 0.2 mm were obtained and these diffract beyond 3A resolution. X-ray photographic analysis demonstrated a rhombohedral unit cell of space group R3 with an equivalent triple centered hexagonal unit cell having dimensions of a = b = 62.9A and c = 264.3A. These crystals were judged to be adequate for a three dimensional structure determination.