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Stabilization of polydopamine modified silver nanoparticles bound trypsin: Insights on protein hydrolysis

Siddiqui, Irfanah, Husain, Qayyum
Colloids and surfaces 2019 v.173 pp. 733-741
casein, chemical bonding, colloids, enzyme activity, hydrolysis, nanocomposites, nanosilver, ovalbumin, pH, proteolysis, storage temperature, storage time, trypsin
This study presents an effective method to enhance the proteolytic activity of trypsin by designing a nanobioconjugate of trypsin and polydopamine coated silver nanoparticles (Ag-PDA). Ag-PDA nanocomposite was synthesized and trypsin was covalently attached to this matrix. A multifold enhancement in enzyme activity was observed after conjugation, with an effectiveness factor of η = 5.62. Conjugated trypsin was more stable to extremes of pH and temperature as compared to normal unconjugated version. Unconjugated trypsin retained only 41% of activity after 60 days of storage at 4 °C, whereas the conjugated enzyme preserved 91% of activity. Immobilized trypsin conserved 83% of activity even after its ten repeated uses. It was found that conjugated trypsin required lower incubation periods for complete hydrolysis of casein, BSA & ovalbumin as compared to free enzyme. Contrary to this, even long hours of incubation with free trypsin were unable to completely digest these proteins. The current observations suggest that Ag-PDA conjugated trypsin could be more suitable for efficient hydrolysis of various proteins under industrial environments.