Acetylcholine Receptor of Limnaea Stagnalis Neurones. Study of the Active Site Functional Groups

1979 ◽  
pp. 293-302 ◽  
Author(s):  
Catherine A. Vulfius ◽  
Olga P. Yurchenko ◽  
V.I. Il'In ◽  
P.D. Bregestovski ◽  
B.N. Veprintsev
Keyword(s):  
Acetylcholine Receptor ◽  
Functional Groups ◽  
Active Site ◽  
Limnaea Stagnalis

scholarly journals Chemical Modification of the Active Site of the Acetylcholine Receptor

1969 ◽  
Vol 54 (1) ◽  
pp. 245-264 ◽  
Author(s):  
Arthur Karlin
Keyword(s):  
Chemical Modification ◽  
Acetylcholine Receptor ◽  
Disulfide Bond ◽  
Active Site ◽  
Quaternary Ammonium ◽  
Competitive Inhibitor ◽  
Affinity Labels ◽  
Electrophorus Electricus ◽  
Depolarizing Agents ◽  
Monoquaternary Ammonium

The receptor for acetylcholine in the subsynaptic membrane of the electroplax of Electrophorus electricus is a protein with a disulfide bond in the vicinity of the active site. This disulfide can be reduced and reoxidized with concomitant inhibition and restoration of the response to acetylcholine and other monoquaternary ammonium-depolarizing agents. Conversely, the bisquaternary hexamethonium, normally a competitive inhibitor, causes depolarization, and the activity of decamethonium is increased following reduction of the disulfide. The reduced receptor can be alkylated by various maleimide derivatives and is then no longer reoxidizable. Some quaternary ammonium maleimide derivatives act as affinity labels of the reduced receptor, alkylating it at a rate three orders of magnitude faster then do uncharged maleimide derivatives. Other types of potential affinity labels also react only with the reduced receptor and the resulting covalently attached quaternary ammonium moieties interact with the active site, strongly activating the receptor. These results suggest a model for the active site and its transitions in which an activator such as acetylcholine bridges between a negative subsite and a hydrophobic subsite in the vicinity of the disulfide, causing an altered conformation around the negative subsite and a decrasee of a few angstroms in the distance between the two subsites.

scholarly journals Crystal structure of NS-134 in complex with bovine cathepsin B: a two-headed epoxysuccinyl inhibitor extends along the entire active-site cleft

2004 ◽  
Vol 381 (2) ◽  
pp. 511-517 ◽  
Author(s):  
Igor ŠTERN ◽  
Norbert SCHASCHKE ◽  
Luis MORODER ◽  
Dušan TURK
Keyword(s):  
Crystal Structure ◽  
Functional Groups ◽  
Carboxy Group ◽  
Active Site ◽  
Binding Sites ◽  
Cathepsin B ◽  
Reactive Group ◽  
Starting Point ◽  
Active Site Cleft ◽  
Binding Inhibitors

The crystal structure of the inhibitor NS-134 in complex with bovine cathepsin B reveals that functional groups attached to both sides of the epoxysuccinyl reactive group bind to the part of active-site cleft as predicted. The -Leu-Pro-OH side binds to the primed binding sites interacting with the His110 and His111 residues with its C-terminal carboxy group, whereas the -Leu-Gly-Meu (-Leu-Gly-Gly-OMe) part (Meu, methoxycarbonylmethyl) binds along the non-primed binding sites. Comparison with the propeptide structures of cathepsins revealed that the binding of the latter part is least similar to the procathepsin B structure; this result, together with the two-residue shift in positioning of the Leu-Gly-Gly part, suggests that the propeptide structures of the cognate enzymes may not be the best starting point for the design of reverse binding inhibitors.

scholarly journals A STUDY ON INTERACTION OF Cd(II) AND DIATOMACEOUS EARTH IN ADSORPTION PROCESS

2010 ◽  
Vol 4 (2) ◽  
pp. 125-131 ◽  
Author(s):  
Nuryono Nuryono ◽  
Suyanta Suyanta
Keyword(s):  
Sulfuric Acid ◽  
Atomic Absorption ◽  
Functional Groups ◽  
Active Site ◽  
Atomic Absorption Spectroscopy ◽  
Diatomaceous Earth ◽  
Adsorption Process ◽  
The Other ◽  
Ph Range ◽  
Adsorption Capability

In this research, interaction occurring in adsorption process between Cd(II) and active site of diatomaceous earth has been studied. The study was carried out by evaluating Cd(II) adsorption on diatomaceous earth at various pHs, either for the earths without treatment, those after being heated or those treated with sulfuric acid and hydrogen chloride. Adsorption was performed by mixing diatomaceous earth, without and with treatments, and Cd(II) solution for one hour at various pHs (2 - 7), and un-adsorbed metallic ion was analyzed by atomic absorption spectroscopy (AAS). The treatments of diatomaceous earth included heating at temperatures of 300, 500, and 900oC for four hours, treatments with acids (3, 8, and 12 M of H2SO4, and 3, 15, and 18 M of HCl solutions for two hours at 150-200oC). Results showed that the increasing of pH from 2.0 to 3.0 and from 6.0 to 7.0 inclined adsorption of Cd(II) from 13.2 to 23.3 mg/g and from 24.0 to 26.4 mg/g, respectively. At a pH range of 3.0 - 6.0 the adsorption slightly increase from 23.3 to 24.0 mg/g. Heating of diatomaceous earth higher than 500oC caused the adsorption capability to be independence of the pH of solution. On the other hand, treatments with acids (H2SO4 and HCl) caused adsorption capability increased significantly with the increase in pH from 3.0 to 6.0. Adsorption evaluation at the pH range investigated showed that adsorption of Cd(II) on diatomaceous earth may be through interaction between Cd2+ and functional groups of T-OH (T = Si/Al).   Keywords: adsorption, adsorbent, cadmium, diatomaceous earth

Comparative Design, In Silico Dockingand Predictive ADME/ TOX Properties of Some Novel 2, 4-hydroxy Derivatives of Thiazolidine-2, 4-diones as PPARγ Modulator

2017 ◽  
Vol 4 (2) ◽  
pp. 11-19 ◽  
Author(s):  
Sabina Yasmin ◽  
Ndumiso N. Mhlongo ◽  
Mahmoud E. Soliman ◽  
Saraswathy GR ◽  
Venkatesan Jayaprakash
Keyword(s):  
Functional Groups ◽  
Active Site ◽  
In Silico ◽  
Metabolic Disorders ◽  
Metabolic Stability ◽  
Simulation Studies ◽  
Docking Protocol ◽  
Derivatives Of

Peroxisome proliferated receptors (PPARs) are important targets for drugs used in the treatment of various metabolic disorders. We have reported 4-hydroxy benzylidene derivatives of thiazolidine-2,4-diones with reversed orientation in the active site of PPARγin our earlier communication. With the reversed conformation of TZD, fitting the established pharmacophore was discussed. The current simulation studies revolves around the 2,4-dihydroxy benzylidene derivatives expecting H-bonding interactions similar to Rosiglitazone’s acidic head. The docking protocol was validated by enrichment studies using decoys and actives from DUD. Designed compounds were showing interactions similar to the actives in the top 10%, 5% and 1%. They also exhibited H-bonding interactions similar to their monohydroxy counterparts without any additional H-bonding interactions due to introduction of additional hydroxy functional groups. Predicted ADMET report reveals that 5 molecules show favourable hERG-I and -II properties and nine compounds show best metabolic stability.

Class D β-lactamases

2020 ◽  
Author(s):  
Eun-Jeong Yoon ◽  
Seok Hoon Jeong
Keyword(s):  
Functional Groups ◽  
Active Site ◽  
Active Sites ◽  
Amino Acid Substitutions ◽  
Family Needs ◽  
Intrinsic Resistance ◽  
Class D ◽  
The Family ◽  
Environmental Bacteria ◽  
Clinically Significant

Abstract Class D β-lactamases are composed of 14 families and the majority of the member enzymes are included in the OXA family. The genes for class D β-lactamases are frequently identified in the chromosome as an intrinsic resistance determinant in environmental bacteria and a few of these are found in mobile genetic elements carried by clinically significant pathogens. The most dominant OXA family among class D β-lactamases is superheterogeneous and the family needs to have an updated scheme for grouping OXA subfamilies through phylogenetic analysis. The OXA enzymes, even the members within a subfamily, have a diverse spectrum of resistance. Such varied activity could be derived from their active sites, which are distinct from those of the other serine β-lactamases. Their substrate profile is determined according to the size and position of the P-, Ω- and β5–β6 loops, assembling the active-site channel, which is very hydrophobic. Also, amino acid substitutions occurring in critical structures may alter the range of hydrolysed substrates and one subfamily could include members belonging to several functional groups. This review aims to describe the current class D β-lactamases including the functional groups, occurrence types (intrinsic or acquired) and substrate spectra and, focusing on the major OXA family, a new model for subfamily grouping will be presented.

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