Method for Determination of Protein Residues in (R)-1-(1-naphthyl) Ethylamine Products Synthesized by Enzymatic Reaction

OBJECTIVE  To establish a method for the determination of protein residues in (R)-1-(1-naphthyl) ethylamine products prepared by enzyme-catalyzed reaction by ultrafiltration centrifugation combined with BCA method.

METHODS  The Amicon^® Ultra-15 ultrafiltration tube was used to purify the solution and enrich the protein. The protein residue in (R)-1-(1-naphthol) ethylamine was determined by BCA method with the detection wavelength of 562 nm.

RESULTS  The protein concentration exhibited a good linear relationship within the range of 25−500 μg·mL⁻¹(r²=0.99). The recovery rates were >70%(n=3×6). After ultrafiltration centrifugation, it was equivalent to collecting 500 mg·mL⁻¹ of the main component solution. The minimum detection limit of protein residues was 5 μg·mL⁻¹, which was equivalent to 0.001% of the principal component content.

CONCLUSION  This method is easy to operation, has good repeatability and high accuracy, and is suitable for the determination of residual protein in (R)-1-(1-naphthalene) ethylamine products prepared by enzymatic reaction.