Quantitation of enzymes in tissue sections by estimation of hydrolytic activity and antigenic determinants

The method and instrumentation for the analysis of enzyme activity and of fluorescent antibody of antigen binding is described. It is based on the microscopic photometry of stain intensities per area of functional units. Thus it was shown that the concentration of aminopeptidase (EC 3.4.2.1) per area in procimal tubule of kidney from pig and mouse is constant. In contrast to the pig the tubules from the outer medulla of the mouse contained twice as much enzyme as those from the cortex. A non constant concentration of aminopeptidase per area was found in crypts of duodenum and in stimulated macrophages.