the change between a dispersed state and a flocculated state of a colloidal agent is used to provide sensitive visual detection and optionally assay of enzyme in a sample . the test cell includes a substrate for the enzyme , and , depending on the action of the enzyme , polymer which protects the colloid from electrolyte - induced flocculation is either formed or destroyed by the test reaction . in a test for a hydrolytic enzyme the colloid loses protection and flocculates . in a test for a polymer - forming enzyme , the colloid gains protection and is prevented from flocculating by added electrolyte , or alternatively , depending on the polymer &# 39 ; s behavior , becomes more sensitive to the flocculating action of the added electrolyte . the measurement may be quantitated using an instrumental monitor . the test uses a natural substrate for the enzyme to be assayed and may achieve rapid speed . the test may be performed using a biologically - derived sample for diagnostically relevant purposes , e . g . to detect an enzyme indicative of periodontal disease . a kit for performing the test is also disclosed .