PROPERTIES OF THE N-TERMINAL 60-KDA-FRAGM ENT OF ELONGATION-FACTOR-2

The N-terminal 60-kDa-fragment of elongation factor 2 from rat liver ( EF-2) was obtained by the limited proteolysis of native EF-2 with elas tase. This fragment consists of 506 N-terminal amino acid residues of EF-2. The conformational properties of both this fragment and EF-2 in solution were studied by circular dichroism and fluorescent spectrosco py. The contents of secondary structure components in the fragment and in the factor that were deduced from CD measurements agreed well with values predicted from their primary structures. Both proteins were re sistant to denaturation with less than or equal to 3 M urea and exhibi ted cooperative denaturation transitions. Temperature melting also pro ceeded cooperatively for the fragment and EF-2. Structural properties of the N-terminal 60-kDa-fragment are discussed in comparison with the biochemical characteristics and 3D structure of prokaryotic elongatio n factor EF-G.