Identification of 2-Keto-3-deoxy-D-glycero-D-galactonononic acid (KDN, Deaminoneuraminic Acid) Residues in Mammalian Tissues and Human Lung Carcinoma Cells

Since the discovery of KDN glycoprotein in 1986, the occurrence of KDN (= 2-keto-3-deoxy-D-glycero-D-galactonononic acid) glycan chains has been reported for different organisms ranging from bacteria to lower vertebrates, including amphibians and fish. Recently, the presence of alpha2-->8-linked oligo/polyKDN groups in mammalian tissues was shown by immunohistochemical and immunoblotting methods. In this communication we report the detection and quantitation of the KDN residues in glycoprotein and glycolipid fractions of rat tissues and human lung cancer cell lines by a highly sensitive fluorometric high-performance liquid chromatography (HPLC) method. We now provide unequivocal chemical proof of the occurrence of KDN in mammals by isolation of KDN from pig submaxillary gland and by structural assignment using chemical methods including fast atom bombardment-mass spectrometry, fluorescence-assisted HPLC analysis, gas-liquid chromatography, and 1H NMR spectroscopy.