Extracellular Lumazine from AggregatingDictyostelium discoideumCells. Influence of pH on its Fluorescence

Abstract
Lumazine is one of the 2 main compounds responsible for the extracellular fluorescence linked with the aggregation ability of Dictyostelium discoideum, strain Ax-2. The other compounds, also having lumazine properties, is, however, different from the 7-hydroxylumazine proposed previously. The influence of pH on the fluorescence of lumazine was studied. The possible use of extracellular pteridines as pH markers was stressed and a method for the determination of the amount of lumazine equivalents in the extracellular medium of aggregating D. discoideum cells is elaborated.