Studies on the purification and chemical characterization of a lytic, anti-trypanosomal factor (ATF-II) from the bacterial species, Pseudomonas fluorescens, were continued. Elemental microanalysis, reversed-phase high performance liquid chromatography (HPLC), Sephadex gel filtration, gel electrophoresis, fast atom bombardment mass spectroscopy (FAB), and nuclear magnetic resonance spectroscopy (NMR) were employed. The purified ATF-II consists of three main components, an alpha-d-glycoside, a peptide, and a component that was not identified, but appears to be a contaminant. More precise HPLC is being used to eliminate this fraction and facilitate an exact determination of the chemical structure. The determination of the chemical structure is essential before studies on synthesis are initiated and pharmacological and toxicological properties are examined employing Trypanosoma cruzi infections.