A COMPARATIVE STUDY OF THE PROTEINS IN NORMAL MECONIUM AND IN MECONIUM FROM MECONIUM ILEUS PATIENTS

Publisher Website
Google Scholar
Abstract
Starch gel electrophoresis and immunoelectrophoresis have been used to confirm previous reports that the highly viscous meconium obtained from patients with meconium ileus is rich in albumin and also contains alpha-, beta-, and gamma-globulins. Normal meconium contains only small amounts of these proteins. It is shown that normal meconium contains a TCA-soluble mucoprotein that is resistant to digestion by the combined action of the proteolytic enzymes trypsin and chymotrypsin. Meconium ileus meconium contains this mucoprotein component in a bound state; it can be released by proteolytic digestion with trypsin and chymotrypsin, or by phenol. Enzymic digestion of meconium ileus meconium destroys all the protein components of abnormal meconium except the resistant mucoprotein, thereby converting the electrophoretic pattern of meconium ileus meconium into a normal pattern. It is suggested that meconium ileus meconium is identical with the contents of the upper small bowel of any normal fetus and that meconium ileus can result when the mechanism of intestinal proteolysis is defective. In an attempt to determine whether meconium ileus meconium contains an abnormal mucoprotein that may be responsible for the viscosity of this material, phenol extraction was used to prepare the mucoprotein from both normal meconium and meconium ileus meconium. About 25% of the dry weight of normal meconium consists of this mucoprotein but the yield of mucoprotein from abnormal meconium is only 2–6% of the dry weight. The relatively low viscosity of mucoprotein from meconium ileus meconium and its presence in only small amounts in the abnormal meconium indicate that it does not play a direct role in the etiology of meconium ileus. The chemical composition of this mucoprotein shows it to be a sialomuco-polysaccharide. Although there are consistent differences between preparations from normal and abnormal meconium, these differences are attributed to partial proteolysis of mucoprotein in the normal digestive tract and are probably not related to cystic fibrosis.