Essential roles of buried phenylalanine in the structural stability of thioredoxin from a psychrophilic Arctic bacterium Sphingomonas sp.

Thioredoxin (Trx), a small redox protein, exhibits thermal stability at high temperatures regardless of its origin, including psychrophiles. Trxs have a common structure consisting of the central β-sheet flanked by an aliphatic cluster on one side and an aromatic cluster on the other side. Although the roles of aromatic amino acids in the folding and stability of proteins have been studied extensively, the contributions of aromatic residues to the stability and function of Trx, particularly Trxs from cold-adapted organisms, have not been fully elucidated. This study examined the roles of aromatic amino acids in the aromatic cluster of a Trx from the psychrophilic Arctic bacterium Sphingomonas sp. PAMC 26621 (SpTrx). The aromatic cluster of SpTrx was comprised of W11, F26, F69, and F80, in which F26 at the β2 terminus was buried inside. The substitution of tyrosine for F26 changed the SpTrx conformation substantially compared to that of F69 and F80. Further biochemical and spectroscopic investigations on F26 showed that the F26Y, F26W, and F26A mutants resulted in structural instability of SpTrx in both urea- and temperature-induced unfolding and lower insulin reduction activities. The Trx reductase (SpTR) showed lower catalytic efficiencies against F26 mutants compared to the wild-type SpTrx. These results suggest that buried F26 is essential for maintaining the active-site conformation of SpTrx as an oxidoreductase and its structural stability for interactions with SpTR at colder temperatures.

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Frank William Ernest Gibson 1923 - 2008

Historical Records of Australian Science ◽

10.1071/hr09024 ◽

2010 ◽

Vol 21 (1) ◽

pp. 55 ◽

Cited By ~ 1

Author(s):

A. J. Pittard ◽

G. B. Cox

Keyword(s):

Escherichia Coli ◽

Amino Acids ◽

Genetic Analysis ◽

Aromatic Compounds ◽

Aromatic Amino Acids ◽

Atp Synthesis ◽

Structure And Function ◽

Innovative Model ◽

Distinguished Research ◽

And Function

Frank Gibson died in Canberra on 11 July 2008. Frank was a highly distinguished research scientist who will be remembered for his pioneering studies in identifying the branch-point compound in the pathway of biosynthesis of a large number of important aromatic compounds followed by a detailed biochemical and genetic analysis of many of the pathways leading to the aromatic amino acids and the so-called aromatic vitamins. Studies on ubiquinone synthesis and function led to an examination of oxidative phosphorylation and the structure and function of the F1F0-ATPase in the bacterium Escherichia coli. This work resulted in the formulation of a highly innovative model, involving rotating subunits of the F0 segment within the membrane and offering an explanation for the mechanism linking proton flow and ATP synthesis.

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The Bβ-sheet in the PAI-1 Molecule Plays an Important Role for Its Stability

Thrombosis and Haemostasis ◽

10.1055/s-0037-1613940 ◽

2000 ◽

Vol 83 (06) ◽

pp. 896-901 ◽

Cited By ~ 4

Author(s):

Guang-Chao Sui ◽

Björn Wiman

Keyword(s):

Amino Acids ◽

Half Life ◽

Ph Dependence ◽

The Other ◽

Wild Type ◽

E Coli ◽

Reactive Center ◽

The Stability ◽

Β Sheet ◽

Pai 1

SummaryWe have investigated the B β-sheet in PAI-1 regarding its role for the stability of the molecule. The residues from His219 to Tyr241 (except for Gly230 and Pro240), covering the s2B and s3B strands, and in addition His185 and His190 were substituted by amino acids with opposite properties. The 23 generated single-site changed mutants and also wild type PAI-1 (wtPAI-1) were expressed in E. coli. Subsequently they were purified by heparin-Sepharose and anhydrotrypsin agarose affinity chromatographies. The stability of the purified PAI-1 variants was analyzed at 37° C and at different pHs (5.5, 6.5 or 7.5). At pH 7.5 and 37° C, single substitutions of the residues in the central portions of both strands 2 and 3 in the B β-sheet (Ile223 to Leu226 on s2B and Met235 to Ile237 on s3B), caused a significant decrease in stability, yielding half-lives of about 10–25% as compared to wtPAI-1. On the other hand, mutations at both sides of the central portion of the B β-sheet (Tyr221, Asp222, Tyr228 and Thr232) frequently resulted in an increased PAI-1 stability (up to 7-fold). While wtPAI-1 exhibited prolonged half-lives at pH 6.5 and 5.5, the PAI-1 variant Y228S was more stable at neutral pH (half-life of 9.6 h at pH 7.5) as compared to its half-life at pH 5.5 (1.1 h). One of the 4 modified histidine residues (His229) resulted in a variant with a clearly affected stability as a function of pH, suggesting that it may, at least in part, be of importance for the pH dependence of the PAI-1 stability. Thus, our data demonstrate that the B β-sheet is of great importance for the stability of the molecule. Modifications in this part causes decreased or increased stability in a certain pattern, suggesting effects on the insertion rate of the reactive center loop into the A β-sheet of the molecule.

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Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) Ubiquitylation as a Novel Pharmaceutical Target for Cystic Fibrosis

Pharmaceuticals ◽

10.3390/ph13040075 ◽

2020 ◽

Vol 13 (4) ◽

pp. 75 ◽

Cited By ~ 2

Author(s):

Ryosuke Fukuda ◽

Tsukasa Okiyoneda

Keyword(s):

Cystic Fibrosis ◽

Structural Stability ◽

Interacting Proteins ◽

Transmembrane Conductance Regulator ◽

Transmembrane Conductance ◽

Surrounding Environment ◽

Cftr Protein ◽

The Stability ◽

And Function ◽

Cystic Fibrosis Transmembrane

Mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene decrease the structural stability and function of the CFTR protein, resulting in cystic fibrosis. Recently, the effect of CFTR-targeting combination therapy has dramatically increased, and it is expected that add-on drugs that modulate the CFTR surrounding environment will further enhance their effectiveness. Various interacting proteins have been implicated in the structural stability of CFTR and, among them, molecules involved in CFTR ubiquitylation are promising therapeutic targets as regulators of CFTR degradation. This review focuses on the ubiquitylation mechanism that contributes to the stability of mutant CFTR at the endoplasmic reticulum (ER) and post-ER compartments and discusses the possibility as a pharmacological target for cystic fibrosis (CF).

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Serine and Cysteine π-Interactions in Nature: A Comparison of the Frequency, Structure, and Stability of Contacts Involving Oxygen and Sulfur

Australian Journal of Chemistry ◽

10.1071/ch14598 ◽

2015 ◽

Vol 68 (3) ◽

pp. 385 ◽

Cited By ~ 13

Author(s):

Hanzala B. Hussain ◽

Katie A. Wilson ◽

Stacey D. Wetmore

Keyword(s):

Amino Acids ◽

High Resolution ◽

Protein Stability ◽

Crystal Structures ◽

Protein Complexes ◽

Aromatic Amino Acids ◽

Biological Macromolecules ◽

Great Stability ◽

Π Interactions ◽

And Function

Despite many DNA–protein π-interactions in high-resolution crystal structures, only four X–H···π or X···π interactions were found between serine (Ser) or cysteine (Cys) and DNA nucleobase π-systems in over 100 DNA–protein complexes (where X = O for Ser and X = S for Cys). Nevertheless, 126 non-covalent contacts occur between Ser or Cys and the aromatic amino acids in many binding arrangements within proteins. Furthermore, Ser and Cys protein–protein π-interactions occur with similar frequencies and strengths. Most importantly, due to the great stability that can be provided to biological macromolecules (up to –20 kJ mol–1 for neutral π-systems or –40 kJ mol–1 for cationic π-systems), Ser and Cys π-interactions should be considered when analyzing protein stability and function.

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Arginine-Amino Acid Interactions and Implications to Protein Solubility and Aggregation

The Journal of Engineering Research [TJER] ◽

10.24200/tjer.vol12iss2pp1-14 ◽

2015 ◽

Vol 12 (2) ◽

pp. 1 ◽

Cited By ~ 2

Author(s):

A. R. Shaikh ◽

D. Shah

Keyword(s):

Amino Acids ◽

Protein Interactions ◽

Density Functional ◽

Protein Solubility ◽

Aromatic Amino Acids ◽

Hydrogen Bond Interactions ◽

Stable Clusters ◽

Pharmaceutical Industries ◽

The Stability

Arginine, useful in protein refolding, solubilization of proteins, and suppression of protein aggregation and non-specific adsorption during formulation and purification, is a ubiquitous additive in the biotechnology and pharmaceutical industries. In order to provide a framework for analyzing the molecular level mechanisms behind arginine/protein interactions in the above context, density functional theory was used to systematically examine how arginine interacts with naturally occurring amino acids. The results show that the most favorable interaction of arginine is with acidic amino acids and arises from charge interactions and hydrogen-bond interactions. Arginine is also shown to form stacking and T-shaped structures with aromatic amino acids, the types of cation–p and N–H…p interactions, respectively, known to be important contributors to protein stability. The analysis also shows that arginine-arginine interactions lead to stable clusters, with the stability of the clusters arising from the stacking of the guanidinium part of arginine. The results show that the unique ability of arginine to form clusters with itself makes it an effective aggregation suppressant and support the interpretations of the current study using experimental and molecular dynamics results available in the literature. The results also contribute to understanding the role of arginine in increasing protein solubility, imparting thermal stability of important enzymes, and designing better additives.

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Enhanced Structural Stability and Electrochemical Performance of LiNi0.6Co0.2Mn0.2O2 Cathode Materials by Ga Doping

Materials ◽

10.3390/ma14081816 ◽

2021 ◽

Vol 14 (8) ◽

pp. 1816

Author(s):

Zhibei Liu ◽

Jiangang Li ◽

Meijie Zhu ◽

Li Wang ◽

Yuqiong Kang ◽

...

Keyword(s):

Electrochemical Performance ◽

Structural Stability ◽

Cathode Materials ◽

Xrd Analysis ◽

Structural Instability ◽

In Situ Xrd ◽

Li Ion ◽

The Stability ◽

Ga Doping

Structural instability during cycling is an important factor affecting the electrochemical performance of nickel-rich ternary cathode materials for Li-ion batteries. In this work, enhanced structural stability and electrochemical performance of LiNi0.6Co0.2Mn0.2O2 cathode materials are achieved by Ga doping. Compared with the pristine electrode, Li[Ni0.6Co0.2Mn0.2]0.98Ga0.02O2 electrode exhibits remarkably improved electrochemical performance and thermal safety. At 0.5C rate, the discharge capacity increases from 169.3 mAh g−1 to 177 mAh g−1, and the capacity retention also rises from 82.8% to 89.8% after 50 cycles. In the charged state of 4.3 V, its exothermic temperature increases from 245.13 °C to more than 271.24 °C, and the total exothermic heat decreases from 561.7 to 225.6 J·g−1. Both AC impedance spectroscopy and in situ XRD analysis confirmed that Ga doping can improve the stability of the electrode/electrolyte interface structure and bulk structure during cycling, which helps to improve the electrochemical performance of LiNi0.6Co0.2Mn0.2O2 cathode material.

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Peripheral cyclic β-amino acids balance the stability and edge-protection of β-sandwiches

Organic & Biomolecular Chemistry ◽

10.1039/c8ob01322e ◽

2018 ◽

Vol 16 (30) ◽

pp. 5492-5499 ◽

Cited By ~ 2

Author(s):

Gábor Olajos ◽

Anasztázia Hetényi ◽

Edit Wéber ◽

Titanilla Szögi ◽

Lívia Fülöp ◽

...

Keyword(s):

Amino Acids ◽

Compact Structure ◽

The Stability ◽

Aminocyclohexanecarboxylic Acid ◽

Β Sheet

cis-2-Aminocyclohexanecarboxylic acid replacements at the edges of β-sandwiches reduce β-sheet propensities just enough to prevent aggregation but still maintain a compact structure.

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