ghosts. Localization mechanisms in enzyme cytochemistry studied with alkaline phosphatase-loaded erythrocyte

Cytochemical localization of enzyme activity is generallyachieved by a chemical capture reaction of the primary enzymeproducts. Since the capture reaction always takes some time,diffusion of primary products away from their original site ofproduction will occur to an a priori unknown extent. In ad-dition, the final product may show supersaturation phenomenaand, consequently, may also diffuse. These diffusion phenom-ena may lead to overestimation of the dimensions of the trueenzyme containing site or even to a completely negative re-action. When nonenzyme sites with great affinity for primaryand/or still soluble final product are present in the vicinity ofthe enzyme site, false localization can result.Reaction schemes that relate enzymic and chemical reac-tions with physical diffusion phenomena have been presented(Holt and O’Sullivan, 1958; Cornelisse et al., 1976). Enzymicactivity, reaction rate constants, diffusion constants, dimen-sions ofthe enzyme site, and precipitability ofthe final productare the variable parameters in the mathematical expressionsof these theoretical considerations. In the present article twotypes of cytochemical enzyme procedures have been investi-gated, i.e.,