A number of phosphorylated fluorochromes were synthesized and tested for the alkaline phosphatase-linked fluorescence assay of membrane-bound nucleic acids. 3-Hydroxy-N-2'- biphenyl-2-naphthalenecarboxamide phosphate ester (HBNP) was found to be the most suitable for the assay. Nonfluorescent HBNP is hydrolyzed by phospholipase bound to the probe DNA to the highly fluorescent 3-hydroxy-N, 2'-biphenyl-2-naphtha-lenecarboxamide ...