Tetracycline Binding to Bovine Serum Albumin Studied by Fluorescent Techniques

Binding of demeclocycline and oxytetracycline to bovine serum albumin was studied using fluorescent methods. The mechanism of binding for tetracyclines is shown to be hydrophobic. The number of binding sites and the equilibrium constants were calculated over a range of protein concentrations. Two strong binding sites, at or near the tryptophan residues of bovine serum albumin, were found for both tetracyclines. The equilibrium constants for tetracyclines increased with increasing protein concentration, and the number of binding sites on the protein decreased with increasing protein concentration. These findings suggest the possibility of a sharing of one tetracycline molecule by more than one protein molecule at relatively high protein concentrations.