Enzyme acetyl choline esterase

The activity of these biofunctional peptides is based on their inherent amino acid composition and sequence. The size of active sequences may vary from 2 to 20 amino acid residues, and many peptides are known to have multifunctional properties [89], e.g., peptides from the sequence 60-70 of P-casein show immunostimulatory, opioid, and angiotensin I converting enzyme (acetyl choline esterase [ACE]) -inhibitory activities. This sequence has been defined as a strategic zone [90,91]. The sequence is protected from proteolysis because of its high hydrophobicity and the presence of proline residues. Other examples of the multi-functionality of milk-derived peptides include the... 

Quon et al. (1985) investigated the stability of esmolol in blood, plasma, red blood cells, and purified enzymes (human serum pseudocholinesterase, human and dog serum albumin, acetyl choline esterase, carbonic anhydrases A and B and human haemoglobin). Udata et al. (1999) studied the hydrolysis of propranolol ester prodrugs in purified acetylcholine esterase. 

Thus (+)-[Ni(phen)3]2+ and (+)-[Ru(phen)3]2+ are more toxic to mice by intraperitoneal injection (153) than are their enantiomers. As the mice exhibited symptoms of curare poisoning (24) which is thought to be due to inhibition of acetyl choline-esterase, the effects of some other complexes on this enzyme were studied. (—)-[Ru(bipy)3]2+ inhibits (153) this enzyme much more than does (- -)-[Ru(bipy)3]2+. However, the enantiomers of [Ru(bipy)3]2+ have equal toxicities to mice (153), and (+)-[Ru(phen)3]2+ is more readily absorbed from the intraperitoneal cavity than is (—)-[Ru(phen)3]2+.The configurations of (—)-[Ru(bipy)3]2+ and (+)-[Ru(phen)3]2+ have been said (44) to be identical on the basis of the physiological work outlined above, but this conclusion, resting as it does on physiological results which are of doubtful relationship to one another is very tenuous, and conflicts with other work (see p. 78). 

Hydrolysis of the postsynaptically bound ACh. The most rapid step of the ACh metabolism is the enzymatic decomposition of ACh. Acetyl choline esterase (EC 3.1.1.7) is a very active enzyme. Rapid hydrolysis is the precondition of rapid recovery of the resting state after transmitting an impulse. 

In 1989, to the best of our knowledge, the first report appeared on the use of an avidin-biotin system for the immobilization of enzymes in the preparation of biosensors. Walt et al. have immobilized biotin-modified enzymes (urease, esterase, and penicillinase) on the surface of biotin-modified optical fiber using avidin as a binder (Figure 5a). They have demonstrated the general use of this procedure in immobilizing several types of enzymes. At nearly the same time, Gunaratna and Wilson used an enzyme column in which choline esterase and choline oxidase were immobilized through avidin-biotin complexation for the determination of acetyl-... 

Doretti L, Ferrara D, Lora S, Schiavon F, Veronese FM (2000) Acetyl choline biosensor involving entrapment of acetylcholine esterase and poly (ethylene glycol)-modifled choline oxidase in a poly (vinyl alcohol) cryogel membrane. Enzyme Microb Technol 27 279-285... 

Assay of enzyme inhibitors. In 1965, Guilbault and co-workers [252] proposed an electrochemical apparatus for monitoring enzyme activity in urethane pads. The immobilized choline esterase hydrolyzed butyryl (or acetyl) thiocholine iodide (Eq, (57)) ... 

Acetyl choline is transient in effect owing to its rapid hydrolysis by the widely distributed enzyme, choline esterase, which resolves it into free choline, with a potency about 100,000 times less than the acetyl ester. Choline esterase is inhibited by eserine (physo-stigmine), application of which prolongs the action of acetyl choline. 

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