Preliminary Purification and Characterization of Adhesive Proteins from Freshwater Mussels

In this study, freshwater mussel adhesive proteins (FMAPs) were extracted by different solvents and preliminarily purified using differential precipitation with ammonium sulphate and acetone. FMAPs extracted by the fourth method (M4) were further purified by twice column chromatography and characterized in terms of isoelectric point, gel electrophoresis, and amino acid composition. Results showed that 50 mM Tris-HCl (pH 7.5) solution containing 1 M NaCl exhibited better extraction efficiency for FMAPs. The purity of FMAPs got further enrichment after column chromatography, and two purified FMAPs fraction I and fraction II with hydroxyl amino acid of higher content (>43.3%) were obtained. Amino acid analysis demonstrated that DOPA contents in fraction I and fraction II were 13.04% and 12.02%, respectively. The isoelectric point of FMAPs was close to pH 9.5.