GALACTOSAMINE IN WALLS OF SLOW-GROWING MYCOBACTERIA

Galactosamine was found consistently as a minor component of the envel ope of five species of slow-growing mycobacteria, including all the ma jor human pathogens, but not three rapid-growing species. The amino su gar was a component of the arabinogalactan of the cell wall skeleton, and occurred at the level of about one residue per arabinogalactan cha in. Its amino group was in the free, un-N-acetylated state. Examinatio n of oligosaccharides released by partial acid hydrolysis of arabino-g alactan by fast atom bombardment-MS and gas chromatography-MS identifi ed a series of oligoarabinans, each possessing one GalN unit, linked t o position 2 of arabinose. It is proposed that the GalN residues occur as stub branches of 1 --> 5-linked arabinose chains in the arabinogal actan. Possible functions of GalN are discussed.