Table 1. Hydrodynamic analysis of SSB variants at 25°C in buffer T.

Protein	300 mM NaCl		2 mM NaCl
	s20,w	f/f0	s20,w	f/f0
SSB	4.23	1.51	4.51	1.49
SSB LD	4.13	1.43	4.31	1.42
SSB LD (αΔW)	4.02	1.43	4.25	1.42
SSB LD (αΔW F)	3.81	1.61	4.15	1.39
βΔW	4.00	1.43	4.24	1.45

Analysis was performed via analytical ultracentrifugation sedimentation velocity at [4-OB] = 750 nM. Each variant predominately formed the 4-OB fold species yielding molecular weights within 10% of their expected values in moderate salt and in low salt. Most experiments performed on variants of SSB LD had some amount of a high molecular weight species present that corresponded to the MW of a dimer of the 4-OB fold species. This high molecular weight species never accounted for more than 4% of the total signal in the experiment.