scholarly journals Acid-catalyzed proton exchange as a novel approach for relaxivity enhancement in Gd-HPDO3A-like complexes

2020 ◽  
Vol 11 (30) ◽  
pp. 7829-7835
Author(s):  
Loredana Leone ◽  
Mariangela Boccalon ◽  
Giuseppe Ferrauto ◽  
István Fábián ◽  
Zsolt Baranyai ◽  
...  
Keyword(s):  
Proton Exchange ◽  
Exchange Mechanism ◽  
Side Chain ◽  
Primary Amide ◽  
Novel Approach ◽  
High Relaxivity ◽  
Acidic Conditions ◽  
Acid Catalyzed ◽  
Amide Side Chain

A novel GdHPDO3A-like complex featuring primary amide side chain induces extraordinary high relaxivity by virtue of a simultaneous double-site proton exchange mechanism under slight acidic conditions.

scholarly journals Recognition properties of receptors consisting of imidazole and indole recognition units towards carbohydrates

2010 ◽  
Vol 6 ◽  
Author(s):  
Monika Mazik ◽  
André Hartmann
Keyword(s):  
Side Chain ◽  
Aromatic Rings ◽  
Binding Studies ◽  
Primary Amide ◽  
Binding Properties ◽  
Two Phase ◽  
Binding Motifs ◽  
H Nmr ◽  
Phase Systems ◽  
Amide Side Chain

Compounds 4 and 5, including both 4(5)-substituted imidazole or 3-substituted indole units as the entities used in nature, and 2-aminopyridine group as a heterocyclic analogue of the asparagine/glutamine primary amide side chain, were prepared and their binding properties towards carbohydrates were studied. The design of these receptors was inspired by the binding motifs observed in the crystal structures of protein–carbohydrate complexes. 1H NMR spectroscopic titrations in competitive and non-competitive media as well as binding studies in two-phase systems, such as dissolution of solid carbohydrates in apolar media, revealed both highly effective recognition of neutral carbohydrates and interesting binding preferences of these acyclic compounds. Compared to the previously described acyclic receptors, compounds 4 and 5 showed significantly increased binding affinity towards β-galactoside. Both receptors display high β- vs. α-anomer binding preferences in the recognition of glycosides. It has been shown that both hydrogen bonding and interactions of the carbohydrate CH units with the aromatic rings of the receptors contribute to the stabilization of the receptor–carbohydrate complexes. The molecular modeling calculations, synthesis and binding properties of 4 and 5 towards selected carbohydrates are described and compared with those of the previously described receptors.

scholarly journals Phosphate-Catalyzed Succinimide Formation from an NGR-Containing Cyclic Peptide: A Novel Mechanism for Deammoniation of the Tetrahedral Intermediate

Molecules ◽  
2018 ◽  
Vol 23 (9) ◽  
pp. 2217 ◽  
Author(s):  
Ryota Kirikoshi ◽  
Noriyoshi Manabe ◽  
Ohgi Takahashi
Keyword(s):  
Conformational Changes ◽  
Density Functional ◽  
Cyclic Peptide ◽  
Density Functional Theory Method ◽  
Proton Exchange ◽  
Computational Method ◽  
Side Chain ◽  
Tetrahedral Intermediate ◽  
Rate Determining Step ◽  
Proton Source

Spontaneous deamidation in the Asn-Gly-Arg (NGR) motif that yields an isoAsp-Gly-Arg (isoDGR) sequence has recently attracted considerable attention because of the possibility of application to dual tumor targeting. It is well known that Asn deamidation reactions in peptide chains occur via the five-membered ring succinimide intermediate. Recently, we computationally showed by the B3LYP density functional theory method, that inorganic phosphate and the Arg side chain can catalyze the NGR deamidation using a cyclic peptide, c[CH2CO–NGRC]–NH2. In this previous study, the tetrahedral intermediate of the succinimide formation was assumed to be readily protonated at the nitrogen originating from the Asn side chain by the solvent water before the release of an NH3 molecule. In the present study, we found a new mechanism for the decomposition of the tetrahedral intermediate that does not require the protonation by an external proton source. The computational method is the same as in the previous study. In the new mechanism, the release of an NH3 molecule occurs after a proton exchange between the peptide and the phosphate and conformational changes. The rate-determining step of the overall reaction course is the previously reported first step, i.e., the cyclization to form the tetrahedral intermediate.

The influence of chirality in the amide side chain on the carbonyl orientation in rotational isomers of 3-carbamoylpyridinium halides

1988 ◽  
pp. 230 ◽  
Author(s):  
Loek A. M. Bastiaansen ◽  
Ton J. M. Vermeulen ◽  
Henk M. Buck ◽  
Wilberth J. J. Smeets ◽  
Jan A. Kanters ◽  
...  
Keyword(s):  
Side Chain ◽  
Rotational Isomers ◽  
Amide Side Chain

scholarly journals CLP-based protein fragment assembly

2010 ◽  
Vol 10 (4-6) ◽  
pp. 709-724 ◽  
Author(s):  
ALESSANDRO DAL PALÙ ◽  
AGOSTINO DOVIER ◽  
FEDERICO FOGOLARI ◽  
ENRICO PONTELLI
Keyword(s):  
Search Strategy ◽  
Protein Structures ◽  
Constraint Solving ◽  
Side Chain ◽  
Space Filling ◽  
Protein Fragment ◽  
Fragment Assembly ◽  
Energy Models ◽  
Novel Approach ◽  
Protein Model

AbstractThe paper investigates a novel approach, based on Constraint Logic Programming (CLP), to predict the 3D conformation of a protein via fragments assembly. The fragments are extracted by a preprocessor—also developed for this work—from a database of known protein structures that clusters and classifies the fragments according to similarity and frequency. The problem of assembling fragments into a complete conformation is mapped to a constraint solving problem and solved using CLP. The constraint-based model uses a medium discretization degree Cα-side chain centroid protein model that offers efficiency and a good approximation for space filling. The approach and adapts existing energy models to the protein representation used and applies a large neighboring search strategy. The results shows the feasibility and efficiency of the method. The declarative nature of the solution allows to include future extensions, e.g., different size fragments for better accuracy.

A novel approach to prepare photocrosslinked sulfonated poly(arylene ether sulfone) for proton exchange membrane

2014 ◽  
Vol 463 ◽  
pp. 58-64 ◽  
Author(s):  
Pushan Wen ◽  
Zhenxin Zhong ◽  
Lizhong Li ◽  
Fengshan Shen ◽  
Xiang-Dan Li ◽  
...  
Keyword(s):  
Proton Exchange Membrane ◽  
Proton Exchange ◽  
Arylene Ether ◽  
Novel Approach ◽  
Exchange Membrane ◽  
Sulfonated Poly

scholarly journals Chemically stabilised extruded and recast short side chain Aquivion® proton exchange membranes for high current density operation in water electrolysis

2019 ◽  
Vol 578 ◽  
pp. 136-148 ◽  
Author(s):  
Stefania Siracusano ◽  
Claudio Oldani ◽  
Maria Assunta Navarra ◽  
Stefano Tonella ◽  
Lucia Mazzapioda ◽  
...  
Keyword(s):  
Current Density ◽  
High Current Density ◽  
Water Electrolysis ◽  
Proton Exchange Membranes ◽  
Proton Exchange ◽  
Side Chain ◽  
High Current ◽  
Short Side

On the turn-inducing properties of asparagine: the structuring role of the amide side chain, from isolated model peptides to crystallized proteins

2018 ◽  
Vol 20 (5) ◽  
pp. 3411-3423 ◽  
Author(s):  
S. Habka ◽  
W. Y. Sohn ◽  
V. Vaquero-Vara ◽  
M. Géléoc ◽  
B. Tardivel ◽  
...  
Keyword(s):  
Gas Phase ◽  
Laser Spectroscopy ◽  
Protein Structures ◽  
Side Chain ◽  
Amide Side Chain ◽  
Model Peptides

The anchoring properties of an asparagine (Asn) residue to its local backbone environment in turn model peptides is characterized using gas phase laser spectroscopy and compared to crystallized protein structures.

scholarly journals Synthesis and characterization of a novel crosslinkable side-chain sulfonated poly(arylene ether sulfone) copolymer proton exchange membranes

RSC Advances ◽  
2020 ◽  
Vol 10 (42) ◽  
pp. 24772-24783 ◽  
Author(s):  
Shouping Wang ◽  
Fugang He ◽  
Qiang Weng ◽  
Diao Yuan ◽  
Pei Chen ◽  
...  
Keyword(s):  
Single Cell ◽  
Proton Exchange Membranes ◽  
Proton Exchange ◽  
Side Chain ◽  
Synthesis And Characterization ◽  
High Proton Conductivity ◽  
Arylene Ether ◽  
High Proton ◽  
Sulfonated Poly

A series of novel crosslinkable and crosslinked side-chain SPAES has been prepared. The S-SPAES(1/2) has high proton conductivity and acceptable single-cell performance.

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