Search results for "choline"

Composite soy lecithin–decylpolyglucoside vesicles: A theoretical and experimental study

2008

In the present work, vesicles made with soy lecithin and a commercial mixture of alkyl polyglucosides were prepared and characterized. Vesicles with a constant amount of soy lecithin and an increasing amount of a decylpolyglucoside surfactant, (OrNS10), were formulated and their physicochemical properties were studied with the aim to design a drug delivery system suitable for different applications. To this purpose, morphology, size distribution, ζ-potential and apparent viscosity of the prepared vesicles were studied. Vesicles were also characterized by using optical and light polarized microscopy, transmission electron microscopy and photon correlation spectroscopy. A stability study was …

Efficient alkali iodide promoted 18F-fluoroethylations with 2-[18F]fluoroethyl tosylate and 1-bromo-2-[18F]fluoroethane

2003

Abstract Radiochemical 18 F-fluorination yields of several compounds using the secondary labelling precursors 2-[ 18 F]fluoroethyl tosylate ([ 18 F]FETos) and 1-bromo-2-[ 18 F]fluoroethane ([ 18 F]BFE) could be considerably enhanced by the addition of an alkali iodide. The radiochemical yield of [ 18 F]fluoroethyl choline for example could be doubled with [ 18 F]BFE and increased from 13% to ≈80% with [ 18 F]FETos. By addition of alkali iodide to the precursor, the 18 F-fluoroethylation yields of established radiopharmaceuticals, especially in the case of automated syntheses, could be significantly increased without major changes of the reaction conditions.

Synthesis and evaluation of tritium labelled 10-methylgalanthamine iodide: a novel compound to examine the mechanism of interaction of galanthamine d…

2003

Summary A new promising galanthamine derivative, 10-[ 3 H]methylgalanthamine iodide, was synthesized for binding studies to nicotinic acetylcholine receptors expressed in Torpedo electric ray electroplaques. Galanthamine was reacted with [ 3 H]methyl iodide to yield 10-[ 3 H]methylgalanthamine iodide with a radiochemical yield of >70% and a specific activity of 32 Ci/mmol after purification via solid phase extraction. To test the ligand properties of the radioligand, calcium imaging and electrophysiology of the non-radioactive analogue were performed to obtain an EC50 of 270 nM, a Hill coefficient of 1.9 and the induced cell current. Copyright # 2003 John Wiley & Sons, Ltd.

Chapter 17: The cholinesterases: a discussion of some unanswered questions

1993

Publisher Summary During the past three decades, a vast body of specificity and kinetic data relating to the cholinesterases has accumulated, which must now be explained by the extremely interesting new sequence and X-ray crystallographic results presented by MassouliC et al. As this chapter shows, the cholinesterases are remarkable among enzymes in having a broad specificity embracing both charged and uncharged substrates but with a clearly expressed preference, at any rate in the aliphatic series, for the acylcholine configuration: a classical example of the principle of complementariness between substrate and active site as the basis for enzyme action. It is well known that AChE exists i…

Chemie an starren Grenzflächen, 10. Kinetisches Verhalten einiger an „Isothiocyanato-Aerosil” immobilisierter Esterasen – Analogversuche mit Insulin

1988

Amino-Aerosil wird mit Thiophosgen nach Gl. (1) in Isothiocyanato-Aerosil 2 (NCS-Aerosil) ubergefuhrt. Trypsin, Cholinesterase und Acetylcholinesterase werden an 2 nach Gl. (2) immobilisiert. Die Aktivitat der immobilisierten Esterasen wird untersucht auf (a) Lagerstabilitat, (b) Temperaturbestandigkeit und (c) pH-Abhangigkeit. Das kinetische Verhalten der immobilisierten Enzyme wird verglichen mit dem der freien, aber mit n-Butylisothiocyanat behandelten Esterasen. Am Beispiel der Cholinesterase, die uber unterschiedliche Ankergruppen mit Aerosil verknupft wurde, wird der Einflus unterschiedlicher Spacergruppen auf die Hydrolysegeschwindigkeit studiert. Aerosile, die mit Acetylcholin-Analo…

Acetylcholine esterase: the structure.

1991

Biochemical Characterization of an Acetylcholine-hydrolyzing Enzyme from Bean Seedlings.

1980

An acetylcholine hydrolyzing enzyme was prepared and purified (40 times) from dwarf bean hypocotyl hooks. The purity of the enzyme was proved by polyacrylamide gel electrophoresis. The molecular weight of the enzyme was determined to be 65,000 daltons. Enzyme activity was the highest at pH 8.0 and between 30 and 36 C. The enzyme had an apparent affinity constant (K(m)) for acetylcholine of 460/micromolar. The affinity for substrate analogs increased from butyrylthiocholine to propionylthiocholine to acetylthiocholine. The enzyme activity was inhibited by choline, neostigmine, physostigmine, manganese, and calcium. Magnesium had no influence on the enzyme activity. We conclude that the enzym…

Phospholipid-based reverse micelles.

1990

Physicochemical investigations on the aggregation of phospholipids (mainly phosphatidylcholines) in organic solvents are reviewed and compared with the aggregation behaviour of phospholipids in aqueous medium. In particular we review the data showing that phosphatidylcholines (lecithins) form reverse micellar structures in certain apolar solvents. In these systems not only low molecular weight compounds but also catalytically active enzymes and entire cells can be solubilized. In addition, highly viscous phosphatidylcholine gels can be obtained in organic solvents upon solubilizing a critical amount of water. Generally, phospholipid-based reverse micelles can be regarded as thermodynamicall…

Mechanisms of Glial Swelling by Arachidonic Acid

1994

The effect of arachidonic acid (AA, 20:4) was analyzed in vitro by employment of C6 glioma cells and astrocytes from primary culture. The cells were suspended in an incubation chamber under continuous control of pH, pO2, and temperature. Cell swelling was quantified by flow cytometry. After a control period, the suspension was added with AA at concentrations of 0.01 to 1.0 mM. Administration of AA induced an immediate, dose dependent swelling in C6 glioma cells or astrocytes. AA-concentrations of 0.01 mM led to an increase of the glial cell volume to 103.0 ± 1.0% of control, 0.1 mM to 110.0 ± 1.5%, and l.0 mM to 118.8 ± 1.5% within 10 min. The swelling response to linoleic acid (18 : 2) was…

Acetylcholine receptors (muscarinic) (version 2019.4) in the IUPHAR/BPS Guide to Pharmacology Database

2019

Muscarinic acetylcholine receptors (nomenclature as agreed by the NC-IUPHAR Subcommittee on Muscarinic Acetylcholine Receptors [45]) are GPCRs of the Class A, rhodopsin-like family where the endogenous agonist is acetylcholine. In addition to the agents listed in the table, AC-42, its structural analogues AC-260584 and 77-LH-28-1, N-desmethylclozapine, TBPB and LuAE51090 have been described as functionally selective agonists of the M1 receptor subtype via binding in a mode distinct from that utilized by non-selective agonists [243, 242, 253, 155, 154, 181, 137, 11, 230]. There are two pharmacologically characterised allosteric sites on muscarinic receptors, one defined by it binding gallami…