Differential stabilities of fetal intestinal disaccharidases determine their relative amounts released into amniotic fluid.

Comparison of relative disaccharidase activities in jejunal mucosa, amniotic fluid, and meconium samples taken from the ileum, proximal and distal colon of 5 human fetuses, indicates that trehalase and lactase are more sensitive to the denaturation conditions existing in the fetal intestinal lumen than maltase, sucrase, palatinase and turanase . Relative activities of sensitive disaccharidases (trehalase and lactase) were also low in the amniotic fluid of these fetuses as compared to the jejunal mucosa. These results suggest that the in vivo stability of disaccharidases, exposed to proteolytic digestion and other denaturing conditions in the fetal intestinal lumen, governs the relative activities of these enzymes released into the amniotic fluid.