Enzyme Activities in Human and Rat Jejunal Mucosa

To define reproducible conditions for the homogenization of small-intestinal biopsy samples, tissue homogenization has been studied by the use of three different homogenizers. Tissue samples of increasing wet weights (0.5-10.8 mg) were homogenized in a fixed volume (1 ml) before DNA and protein were determined. The DNA to protein ratio was calculated for all wet weights and used as a measure for reproducible homogenization. The minimum tissue wet weight needed for analysis (2 mg) was determined from the values obtained for the DNA to protein ratio. Highly sensitive techniques are described in detail for the assay of brush border (maltase, lactase, sucrase, neutral α-glucosidase, alkaline phosphatase, γ-glutamyl transferase, leucyl-β-naphthylamidase), basolateral membrane (5′-nucleotidase), and mitochondrial (succinate dehydrogenase) marker enzymes and for four acid hydrolases (acid phosphatase, acid β-D-galactosidase, N-acetyl-β-D-glucosaminidase, acid diesterase) in human and rat jejunal mucosa. Linear k...