Recombinant human arginase I immobilized on gold and silver nanoparticles: preparation and properties

Metal nanoparticles (NPs), such as gold (Au) and silver (Ag), are important for chemistry, physics, and biology due to their unique optical, electrical, and photothermal properties. Such NPs are widely used for immobilization of various bioactive substances, including peptides, enzymes, antibodies and DNA. The synthesis of silver and gold nanoparticles was carried out by reduction of silver nitrate by glucose and reduction of tetrachloroauric acid by sodium citrate, respectively. The size and structure of the AgNPs and AuNPs were characterized using TEM, AFM and XRD methods. The average size of the AgNPs and AuNPs was between 8 and 15 nm. Recombinant arginase I was immobilized using the carbodiimidepentafluorophenol method on the surface of NPs functionalized with ω-mercaptohexadecanoic acid. It was shown that recombinant human liver arginase I isolated from the yeast Hansenula polymorpha maintains satisfactory stability after immobilization on both NPs. The immobilized arginase retained 40% of its activity on the surface of AuNPs and 25% on AgNPs compared to the free arginase after storage at +4 ºC during 25 days. The immobilized enzyme can be used for assay of arginine in pharmaceuticals, in food products and in blood.