Effect of the protonation state of the amino group on the .cntdot.OH radical induced decarboxylation of amino acids in aqueous solution

1985 ◽  
Vol 89 (14) ◽  
pp. 3139-3144 ◽  
Author(s):  
Joerg Moenig ◽  
Rita Chapman ◽  
Klaus Dieter Asmus
Keyword(s):  
Aqueous Solution ◽  
Amino Acids ◽  
Amino Group ◽  
Protonation State

γ-Radiation-induced carboxylation of pyrrolidine

1976 ◽  
Vol 29 (12) ◽  
pp. 2603 ◽  
Author(s):  
A Davison ◽  
NT Barker ◽  
DF Sangster
Keyword(s):  
Aqueous Solution ◽  
Amino Acids ◽  
Carboxylic Acid ◽  
Hydroxyl Radicals ◽  
Hydrogen Abstraction ◽  
Major Product ◽  
Amino Group ◽  
Γ Radiation ◽  
Neutral Aqueous Solution ◽  
Radiation Induced

Amino acids produced in the γ-radiation-induced carboxylation of pyrrolidine and formate in neutral aqueous solution have been studied. Two products only were found in the ratio 1 : 5.5. The minor product, proline, and the major product, pyrrolidine-3-carboxylic acid, have been characterized. Their presence indicates that the predominant site of hydrogen abstraction from pyrrolidine by radiation-generated hydroxyl radicals is β to the amino group.

scholarly journals On the Use of the Discrete Constant pH Molecular Dynamics to Describe the Conformational Space of Peptides

Polymers ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 99
Author(s):  
Cristian Privat ◽  
Sergio Madurga ◽  
Francesc Mas ◽  
Jaime Rubio-Martínez
Keyword(s):  
Molecular Dynamics ◽  
Amino Acids ◽  
Md Simulations ◽  
Point Of View ◽  
Conformational Space ◽  
Conformational Sampling ◽  
Protonation State ◽  
Constant Ph ◽  
Biochemical Systems ◽  
Constant Ph Molecular Dynamics

Solvent pH is an important property that defines the protonation state of the amino acids and, therefore, modulates the interactions and the conformational space of the biochemical systems. Generally, this thermodynamic variable is poorly considered in Molecular Dynamics (MD) simulations. Fortunately, this lack has been overcome by means of the Constant pH Molecular Dynamics (CPHMD) methods in the recent decades. Several studies have reported promising results from these approaches that include pH in simulations but focus on the prediction of the effective pKa of the amino acids. In this work, we want to shed some light on the CPHMD method and its implementation in the AMBER suitcase from a conformational point of view. To achieve this goal, we performed CPHMD and conventional MD (CMD) simulations of six protonatable amino acids in a blocked tripeptide structure to compare the conformational sampling and energy distributions of both methods. The results reveal strengths and weaknesses of the CPHMD method in the implementation of AMBER18 version. The change of the protonation state according to the chemical environment is presumably an improvement in the accuracy of the simulations. However, the simulations of the deprotonated forms are not consistent, which is related to an inaccurate assignment of the partial charges of the backbone atoms in the CPHMD residues. Therefore, we recommend the CPHMD methods of AMBER program but pointing out the need to compare structural properties with experimental data to bring reliability to the conformational sampling of the simulations.

A colorimetric chemosensor for the sequential detection of copper ion and amino acids (cysteine and histidine) in aqueous solution

RSC Advances ◽  
2015 ◽  
Vol 5 (39) ◽  
pp. 31179-31188 ◽  
Author(s):  
Yong Sung Kim ◽  
Gyeong Jin Park ◽  
Seul Ah Lee ◽  
Cheal Kim
Keyword(s):  
Aqueous Solution ◽  
Amino Acids ◽  
Copper Ion ◽  
Sequential Detection ◽  
Colorimetric Chemosensor

A simple and selective colorimetric chemosensor was reported for the sequential detection of Cu2+, cysteine and histidine.

Physico-chemical Characteristics of Amino Acids in Aqueous Solution of Amikacin Sulphate

2021 ◽  
Author(s):  
Poonam Chaudhary ◽  
◽  
Suvarcha Chauhan ◽  
Vivek Sharma ◽  
Kuldeep Singh ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Amino Acids ◽  
Chemical Characteristics ◽  
Physico Chemical

Formation of α-Keto Acids from α-Amino Acids by the Action of Free Radicals in Aqueous Solution

Science ◽  
1951 ◽  
Vol 114 (2964) ◽  
pp. 412-413
Author(s):  
G. R. A. Johnson ◽  
George Scholes ◽  
Joseph Weiss
Keyword(s):  
Aqueous Solution ◽  
Amino Acids ◽  
Free Radicals ◽  
Keto Acids

Special transport and neurological significance of two amino acids in a configuration conventionally designated as D.

1994 ◽  
Vol 196 (1) ◽  
pp. 297-305 ◽  
Author(s):  
H N Christensen ◽  
A A Greene ◽  
D K Kakuda ◽  
C L MacLeod
Keyword(s):  
Amino Acids ◽  
Receptor Site ◽  
Amino Group ◽  
Carboxylate Group ◽  
Gamma Aminobutyric Acid ◽  
Imino Group ◽  
Group A ◽  
The Central Nervous System ◽  
Lower Homolog ◽  
Alpha Amino Acid

We point out an ability of certain amino acids to be recognized at a biological receptor site as though their amino group bore, instead of an alpha relationship to a carboxylate group, a beta, gamma or delta relationship to the same or a second carboxylate group. For aspartate, the unbalanced position of its amino group between a pair of carboxylates allows its occasional biorecognition as a beta-rather than as an alpha-amino acid, whereas for proline and its homologs, their cyclic arrangement may allow the imino group, without its being replicated, to be sensed analogously as falling at either of two distances from the single carboxylate group. The greater separation might allow proline to be seen as biologically analogous to gamma-aminobutyric acid. This more remote positioning of the imino group would allow the D-form of both amino acids to present its amino group in the orientation characteristic of the natural L-form. The dual modes of recognition should accordingly be signalled by what appears to be low stereospecificity, actually due to a distinction in the enantiorecognition of the two isomers. Competing recognition for transport between their respective D- and L-forms, although it does not prove that phenomenon, has been shown for proline and, significantly, even more strongly for its lower homolog, 2-azetidine carboxylate. Such indications have so far revealed themselves rather inconspicuously for the central nervous system binding of proline, reviewed here as a possible feature of a role suspected for proline in neurotransmission.

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