Novel chemical- and protein-mediated methods for glucosamine detection

We describe two novel approaches for the determination of glucosamine (GlcN). The first approach is based on the chemical derivatization of GlcN with the non-fluorophor 1,3-diphenyl-1,3-propanedione (DPPD), which results in a condensation product with interesting fluorescent properties. The obtained compound was isolated by silica-gel chromatography and its structure elucidated by NMR and mass spectrometry. The second approach is based on a previously undescribed sensitivity of the enzyme glucosamine-6-phosphate deaminase (GPDA) towards GlcN, which resulted in the precipitation of the enzyme. Using a rational enzyme engineering approach and both liquid-based and plate-based screening methods, mutational GPDA variants with significantly improved precipitation properties were identified and characterized. These novel glucosamine detection methods may be a useful addition to the repertoire of currently available glucosamine detection sensors.