While preparing human placenta elongation factor 2 (EF-2), whose purification and some molecular properties are reported, we noticed the presence of numerous protein fractions which did not have EF-2 activity, but were ADP-ribosylated by diphtheria toxin in the presence of NAD+. All these proteins, like EF-2, were selectively retained by a heparin-Sepharose column, which we used as an affinity-chromatography step. This was also observed when EF-2 was prepared, by this purification step, from other sources, i.e. ox liver and two species of yeasts. In order to assess whether these proteins were a degradation product of EF-2, independent proteins or a mixture of both, they were analysed by subjecting them, after [14C]ADP-ribosylation, to exhaustive trypsinolysis. Only one radioactive peptide was found, thus suggesting that those proteins originate from EF-2 by some proteolytic process. Our findings indicate that this proteolysis does not occur after cell disruption, but is more or less active in the intact cell, depending on the system considered.
Purification of elongation factor 2 from human placenta and evidence of its fragmentation patterns in various eukaryotic sources
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A Giovane, L Servillo, L Quagliuolo, C Balestrieri; Purification of elongation factor 2 from human placenta and evidence of its fragmentation patterns in various eukaryotic sources. Biochem J 1 June 1987; 244 (2): 337–344. doi: https://doi.org/10.1042/bj2440337
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