Characterization of cholinesterase molecular forms in the mucosal cells along the intestine of the chicken

Electrostatic interactions of the butyrylcholinesterase dimer of mucosal cells of rat intestine with glycosaminoglycans

The G2 form of butyrylcholinesterase (BChE) of mucosal cells of rat intestine is a rare amphiphilic species, which is related to class II of acetylcholinesterase. Preliminary work indicated that the enzyme can bind heparin and suggested particular properties as compared to other BChEs. Ionic properties of the G2 form BChE were studied with different ionic exchangers. Heparin-Sepharose chromatography, nondenaturing electrophoresis and sucrose gradient centrifugation were used to study heparin interaction with the G2 form BChE. The enzyme structure was modified with reagents that react specifically with amino groups (p-hydroxyphenylglyoxal and 2,4,6-trinitrobenzene sulfonic acid). The G2 form was not retained by DEAE-cellulose which was generally used to isolate BChE from human serum, but was completely bound by strong cation exchanger (Dowex 50). Heparin-Sepharose quantitatively retained the enzyme which was partially eluted only by charged compounds. Nondenaturing gel electrophoresis showed a reduction in enzyme migration with increasing concentrations of heparin and chondroitin sulfate, but not with heparan sulfate. Triton X-100 dissociated the G2 form into monomers but failed to reverse the association between the enzyme and heparin. Reagents specific to amino groups indicated that arginine and lysine residues were involved in this association. In summary, these studies demonstrate that the ionic properties of the G2 form BChE are involved in the binding with heparin. Our results rule out the possibility of amphiphilic interactions in the formation of heparin-enzyme complex and indicate that amino groups are predominately involved in this association.

Butyrylcholinesterase from intestinal epithelial cells of quail, chick and duck: a comparative study during development

1. Epithelial cells of avian intestine express non-specific cholinesterase (butyrylcholinesterase, BuChE) activity both in the embryo and adult animal. 2. Quail, duck and chick exhibit increased BuChE activity during the late embryonic period followed by decreased activity. The minimum value is reached after hatching at day 1 in quail, day 4 in chick and day 6 in duck. 3. The three species display marked sex-related differences mainly during the peri-hatching period. BuChE activity is higher in females than in males. 4. The three globular forms, G1, G2 and G4, are detected during the last days of embryonic development. After hatching, changes in the relative amounts of these forms are related to the disappearance of G2 and the gradual decrease of G4. In adult quail and duck, G4 is not detected and BuChE activity corresponds only to the G1 form. 5. The changes in BuChE activity and distribution of the molecular forms occur in a similar manner in all three species although the embryonic periods differ notably, suggesting that hormonal factors secreted during this period and involved in the preparation of hatching may regulate BuChE activity.

Behaviour of butyrylcholinesterase in the intestinal epithelial cells of starved and refed rats

1. The activity and the molecular characteristics of butyrylcholinesterase were studied in the epithelial cells of the following intestinal segments: duodenum, jejunum, ileum, caecum and colon of starved and refed rats. 2. After starvation, the specific activity of the enzyme is found to increase in the jejunum. The same level of activity was maintained after refeeding. No notable changes were observed in the other intestinal segments after either starvation or refeeding. 3. The behaviour of aminopeptidase, a well-characterized intestinal enzyme, is comparable to that of butyrylcholinesterase, except in the duodenum where the aminopeptidase activity is increased after refeeding. 4. In this cell type, BuChE is found only in its globular forms (G1, G2 and G4). Starvation resulted in a higher value of the sedimentation coefficient of the ileal G2 form, suggesting the existence of a complex between the enzyme and non-cholinesterase components. 5. After refeeding, the sedimentation profile was similar to that of control.

Human intestine epithelial cell acetyl- and butyrylcholinesterase

The epithelial cells of the human intestine exhibit a cholinesterase activity which is restricted to the apex of the villi. This activity displays a maximum in the colon and a minimum in the jejunum. Contrary to most of the studied vertebrates, the human cells present both acetylcholinesterase and butyrylcholinesterase activities, acetylcholinesterase being predominant in all the intestinal segments: duodenum, jejunum, ileum and colon. Like in the other vertebrates, only globular forms are identified by sucrose gradient centrifugation. However, the simultaneous presence, on the one hand of three globular forms (G1, G2 and G4) and, on the other hand of soluble as well as detergent-soluble molecular species seems to be a particular feature of the human cells.

Embryonic and post-natal changes in activity and molecular forms of mucosal cell butyrylcholinesterase in chicken intestine

The mucosal cells of the chicken intestine contain a cholinesterase activity essentially due to butyrylcholinesterase. The enzyme is present during embryonic and post-hatching development. The activity reaches a maximum value at day 19 in ovo and decreases prior to and after hatching up to day 4 ex ovo. Then the activity again rises reaching a second maximum at 2-3 weeks. Beyond this stage, the activity slowly decreases leveling off to the value determined in adult chicken. The enzyme exists as two globular forms (G1 and G4) soluble at low-ionic strengths. The G4 form is predominant in ovo up to day 19. From this stage and after hatching the G1 form is the main one. This change in the form proportion differentiates the mucosal cell butyrylcholinesterase from butyrylcholinesterase of other origins such as the chicken plasma enzyme which always shows a predominant G4 form.