Abstract: A method and compounds useful for this method are described for enzyme-amplified signal detection in analytical assays requiring extremely high detection sensitivity which uses a substrate capable of being transformed by an enzyme from a compound which does not form a luminescent lanthanide chelate into a product which forms a luminescent lanthanide chelate. The method in which a substrate not capable of forming a highly luminescent lanthanide chelate is enzymatically altered to produce a product which forms a highly luminescent lanthanide chelate and hence is particularly useful in time-resolved luminescence analysis as required in many different heterogeneous or homogeneous assay formats is described herein.