Identification of a 2-aminotetrose in a lipid-soluble fraction of rat liver.

Chromatography on DEAE-cellulose of chloroform:methanol:water (10:10:3) extracts obtained from the livers of rats pulsed 50 min with [32P]Pi and D-[1-3H]-mannose yielded two radioactive components which eluted at salt concentrations greater than 0.1 M. One of the components yielded, upon mild acid treatment (20 mM HCl, 100 degrees C, 20 min), a low molecular weight water-soluble component (PO), which contained most of the 32P label associated with the parental lipid-oligosaccharide. PO was periodate-negative, ninhydrin-negative, and permanganate-positive. The phosphate group was stable to strong acid, which converted PO to a single, 32P-labeled product, but the phosphate was readily released by incubation under mild alkaline conditions. Strong alkali produced a product reactive with periodate, ninhydrin, and fluorescamine. When dephosphorylated PO was hydrolyzed with acid and the products were converted to the alditol acetate derivatives, gas chromatography revealed a single major component. Gas chromatography/mass spectroscopy of this compound showed it to be the derivative of a 2-acetamido-2-deoxytetrose. That 2-acetamido-2-deoxytetrose is glycosidically bound in PO is indicated by the fact that PO must be hydrolyzed by strong acid before reduction with NaBD4 is able to incorporate deuterium into the tetrose.