Immunochemical and biochemical investigation of serum cholinesterase in hyperlipidaemia

Darlow, John Michael (1991) Immunochemical and biochemical investigation of serum cholinesterase in hyperlipidaemia. Masters thesis, Memorial University of Newfoundland.

[English] PDF (Migrated (PDF/A Conversion) from original format: (application/pdf)) - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. Download (39MB) [English] PDF - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. (Original Version)

Abstract

Serum cholinesterase is an enzyme similar to acetylcholinesterase but of unknown function. Activity varies widely between individuals and numerous variants are known. Numerous studies have related the activity of serum cholinesterase to serum lipid concentrations but it is not known whether the enzyme plays a part in lipoprotein metabolism nor, if it does, whether this is related to its catalytic activity or to some other feature of the protein. It was therefore decided to compare the relationships of its concentration and activity to the concentrations of serum lipids and lipoproteins. -- Cholinesterase was purified from human serum, and antiserum was raised in a rabbit. The antiserum was used to measure the concentration of the enzyme by radial immunodiffusion in sera from 117 blood donors and 282 patients for whom serum lipid profiles had been requested. -- In the donor group the correlation between activity and concentration of the enzyme was 0.95 and there was little difference between the correlations of the two measures of cholinesterase with lipids. In the patient group the correlation between serum cholinesterase activity and concentration was only 0.88 and all the lipid indices correlated better with the concentration of cholinesterase than with activity. This was probably because of variable loss of activity during transport and storage, and because of enzyme inhibition by drugs. -- For further analysis the patients were preferred because they had fasted before blood sampling and had a greater range of lipid concentrations. Correlations with cholinesterase concentration were in the order 'total LDL' (LDL + VLDL) > VLDL > triacylglycerols > cholesterol. The correlation coefficients were similar, 0.51 with 'total LDL' as against 0.41 with cholesterol, but the shapes of the plots were markedly different. The plot of cholinesterase against cholesterol showed very weak relationship. The plot against triacylglycerols showed a well-defined triangular shape. At lower triacylglycerol concentrations a wide range of cholinesterase concentrations was found but with high triacylglycerol concentrations the enzyme concentration was always high. The possible nature of the relationship is discussed. -- In the preparatory stages, impurities occurring in affinity-purified cholinesterase were investigated by western blotting; and in concentration measurement, reproducible variation in precipitin ring patterns between individuals was observed. -- Key words: Serum cholinesterase concentration; serum lipids; immunological variation of serum cholinesterase.

Actions (login required)

View Item