STRUCTURAL CHARACTERIZATION AND BIOLOGICAL-ACTIVITY OF RECOMBINANT HUMAN EPIDERMAL GROWTH-FACTOR PROTEINS WITH DIFFERENT N-TERMINAL SEQUENCES

The primary structures and molecular homogeneity of recombinant human epidermal growth factors from different suppliers were characterized a nd their biological activities evaluated by a standard DNA synthesis a ssay. Molecular weight determinations using Cf-252-prasma-desorption a nd electrospray mass spectrometry in combination with N- and C-termina l sequence analysis and determination of intramolecular disulfide brid ges revealed that one recombinant protein had the correct human-identi cal structure (54 aa residues; 6347 Da). In contrast, a second recombi nant protein (7020 Da) was found to contain a pentapeptide (KKYPR) ins ert following its N-terminal methionine. This structural variant showe d a significant reduction in its capacity to stimulate DNA synthesis.