A computer model of glycosylated human butyrylcholinesterase

The three-dimensional structure of human serum butyrylcholinesterase (BuChE) was modeled using a computer-based amino acid replacement strategy and the known coordinates of crystallized acetylcholinesterase (AChE) from Torpedo californica. The BuChE model was then energetically minimized with dynamic iterations of an adopted basis Newton-Raphson algorithm and the program CHARMM. Hypothetical glycosylation of this structure based upon the known carbohydrate composition of the enzyme was also performed. The glycosylated, minimized model predicts that the tertiary structure of BuChE could be very similar to AChE but that the entrance of the narrow channel leading toward its active site triad probably differs. All nine of the known N-linked oligosaccharides of BuChE are predicted to occur away from the putative active site channel and most are located on one face of the monomer.