To identify the native ligands of tear lipocalins, tear proteins were
separated by size exclusion chromatography and the lipid content in th
e major protein fractions identified. Lipids extracted from native tea
rs and purified tear lipocalins comigrated with fatty acids, fatty alc
ohols, phospholipids, glycolipids, and cholesterol on thin layer chrom
atograms. Abundant stearic and palmitic acids as well as cholesterol,
and lesser amounts of lauric acid were specifically identified in extr
acts of purified lipocalins by gas chromatography-mass spectroscopy. A
preliminary study of the ligand-protein interaction was carried out u
sing nitroxide spin-labeled lipids.