Acylcholines

Acetylcholinesterase (EC 3.1.1.7) (AChE) Acetylcholine acetylhydrolase True ChE ChE I ChE Acet-ylthiocholinesterase Acetylcholine hydrolase Acetyl (3-methylcholinesterase Erythrocyte ChE Butyrylcholinesterase (EC 3.1.1.8) (BChE or BuChE) ChE Pseudocholinesterase Plasma ChE Acylcholine acylhydrolase Non-specific ChE ChEII Benzoylcholinesterase Propionylcholinesterase... 

Potentiometric enzyme-based electrodes have found application in clinical, pharmaceutical, food and biochemical analyses to enable the selective determination of a wide range of important enzyme substrates, including amino acids, esters, amides, acylcholines, /Mactam antibiotics, sugars, enantioselective drugs and many others [74]. 

Cholinesterase Acylcholine acylhydrolase, butyrylcholinesterase, pseudocholinesterase Choline esters and other esters... 

In contrast to acetylcholinesterase, cholinesterase (acylcholine acyl-hydrolase, butyrylcholinesterase, EC 3.1.1.8) exhibits relatively unspecific esterase activity toward choline esters, with abroad specificity relative to the size of the acyl group. The enzyme is synthesized in the liver and can be found in smooth muscle, adipocytes, and plasma. Its physiological role remains partly obscure, but there is evidence that it is present transiently in the embryonic nervous system, where it is replaced in later stages of development by acetylcholinesterase. It has, therefore, been suggested that cholinesterase functions as an embryonic acetylcholinesterase. 

This enzyme [EC 3.1.1.8] (also known as cholinesterase, pseudocholinesterase, acylcholine acylhydrolase, nonspecific cholinesterase, and benzoylcholinesterase) catalyzes the hydrolysis of an acylcholine to generate choline and a carboxylic acid anion. A variety of choline esters and a few other compounds can serve as substrates. 

Succinylcholine is a neuromuscular blocking agent, which is used clinically to cause muscle relaxation. Its duration of action is short due to rapid metabolism—hydrolysis by cholinesterases (pseudocholinesterase or acylcholine acyl hydrolase)—in the plasma and liver to yield inactive products (Fig. 7.55). Thus, the pharmacological action is terminated by the metabolism. However, in some patients, the effect is excessive, with prolonged muscle relaxation and apnea lasting as long as two hours compared with the normal duration of a few minutes. 

There are several procedures that can provide some information on the chemical nature of an alkenylacylcholine phosphoglycerides. Again, at this point as with the alkyl ether acylcholine phosphoglycerides, it is assumed that a highly purified sample (containing no diacyl or alkylacyl components) is available. Later the methodology to be used with mixtures will be discussed. Certain of these maneuvers have been mentioned earlier in this and in the previous chapter. 

Fatty acids and derivatives Acylcamitines, acylcholine, caprylic acid, capric acid, oleic acid, phospholipids, mono- and diglycerides, sodium laurate Membrane disruption... 

Acetyl-chohnesterases (AChE, EC 3.1.1.7, also called true cholinesterase) and acylcholine acylhydrolases (or pseudocholinesterases including butyryl-cholinesterase, BuChE, EC 3.1.1.8) are commercially available enz5mies from different biological sources that catalyse the hydrolysis of acetyl- or butyryl-choline into choline and acetate or butyrate, respectively, according to the following reaction ... 

Cholinesterases (ChEs) are a ubiquitous group of enzymes that hydrolyze esters of choline. A well-known example is acetylcholinesterase (AChE, acetyl choline hydrolase, EC 3.1.1.7), the enzyme responsible for hydrolyzing the important neurotransmitter acetylcholine (ACh). Another ChE is butyrylcholi-nesterase (BuChE, acylcholine acylhydrolase, EC 3.1.1.8), also known as nonspecific cholinesterase. The preferred substrate for AChEs is ACh BuChEs prefer to hydrolyze esters like butyrylcholine and propionylcholine. Both AChE and BuChE are inhibited by some organophosphate (OP) and carbamate (CB) esters and also by other chemicals. 

Acylcholine acylhydrolase Pseudochoiinesterase, benzoyl.. cholineesterase II (scrum cholinesterase). - ChL (SChE)... 

The other cholinesterase is acylcholine acylhydrolase (EC 3.1.1.8, acylcholine acylhydrolase, CHE) it is also called pseudocholinesterase, serum cholinesterase, butyryl-choHnesterase, or choline esterase II. Although it is found in the liver, pancreas, heart, white matter of the brain, and serum, its biological role is unknown. The assay of this enzyme is clinically useful. 

Findings of and for a series of n-acylcholine esters are reported in Reference DIO, and inhibition data for 16 inhibitors, including SDC, are reported in Reference KIO,... 

Pseudocholinesterase. Acylcholine acylhydrolase. Butyrylcholine esterase. Non-specific cholinesterase. 

There are two main enzymes of interest. Acetylcholinesterase (AChE EC 3.1.1.7) has an affinity for the substrate acetylcholine and it is found in the erythrocytes and nervous tissue. The enzyme is sometimes referred to as true cholinesterase, and it exists in differing polymorphic forms (Skau 1985). Butyrylcholinesterase (BuChE, acylcholine acylhydrolase, EC 3.1.1.8)—also known as pseudocholinesterase or nonspecific cholinesterase— has affinities for the substrates butyrylcholine and/or pro-pionylcholine, which are dependent on the animal species (Myers 1953 Ecobichon and Comeau 1973 Scarsella et al. 1979 Unakami et al. 1987 Evans 1990 Matthew and Chapin 1990 Woodard et al. 1994). 

Evans, G. O. 1990. Species relationships for plasma acylcholine hydrolase using three different substrates. In Fourth Congress of International Society for Animal Clinical Biochemistry, p. 270. University of California, Davis. 

EC 3.1.1.8 Cholinesterase An acylcholine-l-HjO choline-(-a carboxylic acid Blood FGM... 

Cerebroside-3-sulphate 3-sulphohydrolase Poly[ 1,4-p-(2-acetamido-2-deoxy-D-glucoside)] glycanohydrolase Acylcholine acyl hydrolase Chondroitin AC lyase... 

Enzyme assays based on inhibition effects are not as commonly employed as substrate determinations. but one or two are very important. Preeminent is the determination of organophosphorus compounds by using their inhibitory effect on cholinesterase enzymes (E.C. 3.1.1.8—the first digit signifies a hydrolase enzyme, the second that the compounds hydrolyzed are esters, and the third that they are phosphoric monoesters). The latter catalyze the conversion of acylcholines to choline and the corresponding acid ... 

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