Essential amino acids for the stability of human butyrylcholinesterase as predicted by CUPSAT server.

Although butyrylcholinesterase (BChE) is ubiquitous in the human system, its physiological function has often been questioned. Yet BChE has been the subject of active research since its discovery six decades ago. From an evolutionary view point, its stabilized existence even in absence of physiological function spared it from extinction. Herein, we present results on the amino acid residues essential for its stability using CUPSAT server. Out of the 523 amino acids analyzed, 168 were identified to be vital for stability of the protein, and further categorized into three classes. The first class has 82 sites wherein any amino acid substitution results in instability. The second class has 52 sites where on one amino acid substitution alone stability is observed, while the third class has 34 sites where even on two different substitutions, stability is maintained. These sites are distributed throughout the different categories of protein secondary structure, with the order of priority: random coils, alpha-helices and beta-strands. Multiple sequence alignment of BChE showed that most of these residues (85.1%) are within the conserved region, while the few that are not at the conserved region are proposed to be unique residues (14.9%) to the protein which do not show identity with other known homologs. Moreover, majority of the amino acid residues in the functional regions of human BChE do not show instability upon point mutation, indicative of the residue-wise separation for stability and function. Specifically, the active site S198 on mutation does not show instability, while L318P is highly unstable. In addition, S53, G212 and W430 are not involved in its stability and in fact the protein is stable even with all other 19 substitutions. In conclusion, this study bodes well as a forerunner for mutation and protein engineering studies of BChE.

Successful pediatric living donor liver transplantation from carrier to carrier of hereditary butyrylcholinesterase variant.

Hypocholinesterasemia is often observed clinically, especially in various liver diseases. Not well known, however, is the fact that some patients have a hereditary BChE variant. Little has been reported on liver transplants associated with this hereditary BChE variant. Furthermore, no cases have been reported of a LDLT involving hereditary BChE variant that had been diagnosed preoperatively. A 23-month-old girl who had had a failed Kasai operation for biliary atresia underwent a liver transplant using as a graft her father's lateral segment. Preoperatively, she had been diagnosed with hypocholinesterasemia. As the donor, her father had undergone a preoperative examination, during which he was found to also have hypocholinesterasemia. DNA sequencing revealed that both had the hereditary BChE variant. The unique mutation caused a frame-shift mutation. Variant K was also detected. The patient was discharged 143 days after the operation and has had no problems with immunosuppression since. In conclusion, we report that the hereditary BChE variant is not a contraindication for either transplantation or living liver donation.

Proposed nomenclature for human butyrylcholinesterase genetic variants identified by DNA sequencing.

1. New information identifying nucleotide alterations of human butyrylcholinesterase allows the use of more specific nomenclature for the variants commonly known as atypical, fluoride, silent, and K variant. 2. In addition to suggesting a system of trivial names and abbreviations, we provide a list of formal names that follow the guidelines of the Committee for Human Gene Nomenclature. 3. It is suggested that formal names be included in publications whenever possible.

Amphiphilic and nonamphiphilic forms of Torpedo cholinesterases: II. Electrophoretic variants and phosphatidylinositol phospholipase C-sensitive and -insensitive forms.

We report an electrophoretic analysis of the hydrophobic properties of the globular forms of acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) from various Torpedo tissues. In charge-shift electrophoresis, the rate of electrophoretic migration of globular amphiphilic forms (Ga) is increased at least twofold when the anionic detergent deoxycholate is added to Triton X-100, whereas that of globular nonamphiphilic forms (Gna) is not modified. The G2a forms of the first class, as defined by their aggregation properties, are converted to nonamphiphilic derivatives by phosphatidylinositol phospholipase C (PI-PLC) and human serum phospholipase D (PLD). AChE G2a forms from electric organs, nerves, skeletal muscle, and erythrocyte membranes correspond to this type, which also exists in very small quantities in detergent-solubilized extracts of electric lobes and spinal cord. They present different electrophoretic mobilities, so that each of these tissues contains a distinct "electromorph," or two in the case of electric organs. The G2a forms of the second class (AChE in plasma, BuChE in heart), as well as G4a forms of AChE and BuChE, are insensitive to PI-PLC and PLD but may be converted to nonamphiphilic derivatives by Pronase.

[Procedure for identifying atypical variants of pseudocholinesterase for the prevention of prolonged apnea induced by succinylcholine]. / Procedimento per l'individuazione delle varianti atipiche della pseudocolinesterasi ai fini della prevenzione dell'apnea protratta indotta dalla succinildicolina.

The simple Sclavo test based on succinyldicholine hydrolysis and on the following reaction with 5,5'-dithio-bis-2-nitrobenzoic acid for detection of the atypical patterns of serum cholinesterase has been investigated. A yellow staining appears but in presence of the atypical forms of the enzyme. Analysis of 4055 serum samples by the 430 Selective Analyzer Sclavo allowed the identification of one atypical homozygous patient. Prolonged apnoea induced by use of succinyldicholine as a neuromuscular blocking agent during anaesthesia may be avoided by use of this test.