Factors in biological fluids affect gel filtration behavior of epidermal growth factor

There have been conflicting reports on the presence of multiple forms of epidermal growth factor (EGF) in human saliva. The present study was initiated to study the gel filtration behavior of EGF in saliva and other biological fluids. In addition, studies were performed to determine if there were factors in saliva or other biological fluids that would influence the gel filtration behavior of EGF. Gel filtration studies with saliva and urine demonstrated EGF migration consistent with a molecular weight of 35 kDa with no heterogeneity observed. The addition of radiolabeled EGF to either saliva or urine resulted in an altered migration on gel filtration. These results provide evidence for a protein-peptide interaction in saliva and other biological fluids that alters the apparent physical properties of mature EGF.