NEC5 is a flavoprotein. A, SDS-PAGE analysis of purified NEC5 protein. Lane 1, Mr standards; lane 2, 15 μg of purified NEC5 protein. B, Fluorescence excitation and emission spectra of the purified NEC5 protein. C, UV fluorescence of NEC5 proteins. Lane 1, One hundred microliters of crude nectar; lane 2, ammonium sulfate precipitated nectar proteins from 1 mL of nectar were electrophoresed on a 12% SDS-PAGE gel and exposed to UV light on a transilluminator (approximately 366 nm), and the illuminated gel was photographed.