The Overriding Roles of Concentration and Hydrophobic Effect on Structure and Stability of Heme Protein Induced by Imidazolium-Based Ionic Liquids

Jha, Indrani; Kumar, Awanish; Venkatesu, Pannuru

doi:10.1021/acs.jpcb.5b04660

Cited by 36 publications

(22 citation statements)

References 51 publications

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“…The theory of the Hofmeister series was successfully applied to predict the stability of proteins in the presence of a variety of salts. Similar Hofmeister series of alkylimidazolium cations were demonstrated by several different studies [ 13 , 22 ]. For instance, the hydrophobic force was the dominant interaction between alkylimidazolium cations and hemeprotein hemoglobin, which also gradually increased with the increase in the cation chain length [ 22 ].…”

Section: Discussionsupporting

confidence: 80%

Molecular Mechanisms Underlying Inhibitory Binding of Alkylimidazolium Ionic Liquids to Laccase

et al. 2017

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Water-miscible alkylimidazolium ionic liquids (ILs) are “green” co-solvents for laccase catalysis, but generally inhibit enzyme activity. Here, we present novel insights into inhibition mechanisms by a combination of enzyme kinetics analysis and molecular simulation. Alkylimidazolium cations competitively bound to the TI Cu active pocket in the laccase through hydrophobic interactions. Cations with shorter alkyl chains (C2~C6) entered the channel inside the pocket, exhibiting a high compatibility with laccase (competitive inhibition constant Kic = 3.36~3.83 mM). Under the same conditions, [Omim]Cl (Kic = 2.15 mM) and [Dmim]Cl (Kic = 0.18 mM) with longer alkyl chains bound with Leu296 or Leu297 near the pocket edge and Leu429 around TI Cu, which resulted in stronger inhibition. Complexation with alkylimidazolium cations shifted the pH optima of laccase to the right by 0.5 unit, and might, thereby, lead to invalidation of the Hofmeister series of anions. EtSO4− showed higher biocompatibility than did Ac− or Cl−, probably due to its binding near the TI Cu and its hindering the entry of alkylimidazolium cations. In addition, all tested ILs accelerated the scavenging of 2, 2′-azino-bis-(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radicals, which, however, did not play a determining role in the inhibition of laccase.

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Section: Discussionsupporting

confidence: 80%

Molecular Mechanisms Underlying Inhibitory Binding of Alkylimidazolium Ionic Liquids to Laccase

et al. 2017

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“…34 Till now, the interactions of SAILs and blood plasma protein hemoglobin have been scarcely investigated. [38][39][40] Venkatesu et al have studied the conformational stability of Hb in the presence of varying concentrations of ionic liquids using spectroscopy and molecular docking techniques. 38 In another report they have investigated the interactions and effect of ionic liquids on the stability/destability of Hb using various techniques.…”

Section: Introductionmentioning

confidence: 99%

“…[38][39][40] Venkatesu et al have studied the conformational stability of Hb in the presence of varying concentrations of ionic liquids using spectroscopy and molecular docking techniques. 38 In another report they have investigated the interactions and effect of ionic liquids on the stability/destability of Hb using various techniques. 39 Thus, the scarcity of such studies in the literature prompted us to carry out a detailed analysis of interaction phenomena in the Hb-SAIL systems because such studies are of prime importance in the eld of biotechnological areas.…”

Section: Introductionmentioning

confidence: 99%

Surface active ionic liquid induced conformational transition in aqueous medium of hemoglobin

2017

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“…and Hb29 where destabilization tendency of the ILs increased with increasing chain length of the cation of ILs.From our studies of heme protein (Hb and Mb), it can be seen that only very few of the ammonium-based ILs stabilized heme proteins while imidazolium-based ILs proved to be destabilizer.Hence, the search for the IL which could provide stability to Hb was prime aim of our study. The literature survey about the interaction of imidazolium-based ILs with different proteins suggests the frequent use of ILs based on 1-alkyl-3-methylimidazolium chloride ILs where the alkyl group is saturated group.30-37 The studies carried out by Zhang and coworkers 38, 39 proved 1-allyl-3-methylimidazolium chloride ([Amim][Cl]) to be nonderivatizing solvent for cellulose.…”

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confidence: 98%

Unprecedented Improvement in the Stability of Hemoglobin in the Presence of Promising Green Solvent 1-Allyl-3-methylimidazolium Chloride

Jha

Venkatesu

2015

ACS Sustainable Chem. Eng.

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In this article, we have explored the influence of peculiar member of imidazolium-based ionic liquid (IL) 1-allyl-3-methylimidazolium chloride ([Amim][Cl]) on the stability of haemoglobin (Hb) by using fluorescence, thermal fluorescence, ANS fluorescence, circular dichroism (CD) spectroscopy and dynamic light scattering (DLS) measurements. In the attempt of searching of IL which can provide stability to Hb, for the first time, we have successfully shown the stability of Hb in [Amim][Cl]. Our results show that [Amim][Cl] stabilizes the Hb native structure in concentration dependent manner which indicates to fact that the concentration of IL is very crucial to determine the stabilization/destabilization of the protein in ILs. Here, we have observed that low concentration of IL provides stability to the protein while high concentration destabilizes the protein. The commendatory results obtained from the multi spectroscopic approaches provided some guidance regarding the mechanism of interaction between Hb and [Amim][Cl]. The predicted mechanism may be the accumulation of imidazolium cation on the protein surface and tendency of anion to remain in the bulk phase ultimately resulting in stabilization of the protein since; this can in direct/indirect way affect the hydrogen bonding of protein with the surrounding water. on the basis of our results [Amim][Cl] seems to be novel solvent for the stability of Hb, however, further studies with other proteins need to be carried out for further information. CONCLUSION Our results illustrate that interactions of ions of ILs with proteins are important for understanding the effects shown by them on proteins whether stabilization/destabilization. These interactions are governed by the ions present as well as the concentrations used. In this work [Amim][Cl] has been identified as a compatible solvent for Hb structure, nevertheless, the stabilization tendency being concentration dependent. Low concentration of [Amim][Cl] stabilized Hb while higher concentration destabilized Hb. Therefore, the results obtained here facilitate a much better understanding of protein folding/unfolding in IL. Hence, this IL was found to be stabilizing agent for Hb. Since, [Amim][Cl] is thermally stable as well as non-volatile, consequently it can be supposed to be promising green/biocompatible solvent for the proteins. However, further research with other proteins in the presence of this IL is required. Also, from our research this becomes completely clear that the role of alkyl group of imidazolium ILs is vital in determining the protein stability. Therefore, this work can encourage designing of novel ILs which can provide stability to many other proteins. ASSOCIATED CONTENT Supporting InformationThe supporting information is available free of charge on the ACS Publications website Thermal fluorescence spectra analysis of the Hb in buffer and in different concentrations of [Amim][Cl] (Figures S1-S7). Synopsis: The native structure of Hb concentration of [Amim][Cl] Graphical AbstractUnprecedented Improv...

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The Overriding Roles of Concentration and Hydrophobic Effect on Structure and Stability of Heme Protein Induced by Imidazolium-Based Ionic Liquids

Cited by 36 publications

References 51 publications

Molecular Mechanisms Underlying Inhibitory Binding of Alkylimidazolium Ionic Liquids to Laccase

Molecular Mechanisms Underlying Inhibitory Binding of Alkylimidazolium Ionic Liquids to Laccase

Surface active ionic liquid induced conformational transition in aqueous medium of hemoglobin

Unprecedented Improvement in the Stability of Hemoglobin in the Presence of Promising Green Solvent 1-Allyl-3-methylimidazolium Chloride

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