The two dimeric forms of RNase A

In 1965 Fruchter and Crestfield (J, Biol, Chem, 240, 2868-3874) observed th at dimeric RNase A prepared by lyophilization from acetic acid could be sep arated into two forms, Surprisingly, no other structural or functional diff erences could be detected between the two forms. In 1998 a structure for di meric RNase A was determined by X-ray crystallography by Liu et al, (Proc, Natl, Acad, Sci, USA 95, 3437-3442). We found that the two forms of dimeric RNase A have indeed different structural and functional properties, and su ggest that the dimer whose structure was investigated by Liu and coworkers may be identified with the lesser form of dimeric RNase A. (C) 2000 Federat ion of European Biochemical Societies.