Research

15 pages, 3249 KiB

Open AccessArticle

Hydration Dynamics of Model Peptides with Different Hydrophobic Character

by Laura Lupi, Brenda Bracco, Paola Sassi, Silvia Corezzi, Assunta Morresi, Daniele Fioretto, Lucia Comez and Marco Paolantoni

Life 2022, 12(4), 572; https://doi.org/10.3390/life12040572 - 12 Apr 2022

Cited by 1 | Viewed by 1639

Abstract

The multi-scale dynamics of aqueous solutions of the hydrophilic peptide N-acetyl-glycine-methylamide (NAGMA) have been investigated through extended frequency-range depolarized light scattering (EDLS), which enables the broad-band detection of collective polarizability anisotropy fluctuations. The results have been compared to those obtained for N [...] Read more.

The multi-scale dynamics of aqueous solutions of the hydrophilic peptide N-acetyl-glycine-methylamide (NAGMA) have been investigated through extended frequency-range depolarized light scattering (EDLS), which enables the broad-band detection of collective polarizability anisotropy fluctuations. The results have been compared to those obtained for N-acetyl-leucinemethylamide (NALMA), an amphiphilic peptide which shares with NAGMA the same polar backbone, but also contains an apolar group. Our study indicates that the two model peptides induce similar effects on the fast translational dynamics of surrounding water. Both systems slow down the mobility of solvating water molecules by a factor 6–8, with respect to the bulk. Moreover, the two peptides cause a comparable far-reaching spatial perturbation extending to more than two hydration layers in diluted conditions. The observed concentration dependence of the hydration number is explained considering the random superposition of different hydration shells, while no indication of solute aggregation phenomena has been found. The results indicate that the effect on the dynamics of water solvating the amphiphilic peptide is dominated by the hydrophilic backbone. The minor impact of the hydrophobic moiety on hydration features is consistent with structural findings derived by Fourier transform infrared (FTIR) measurements, performed in attenuated total reflectance (ATR) configuration. Additionally, we give evidence that, for both systems, the relaxation mode in the GHz frequency range probed by EDLS is related to solute rotational dynamics. The rotation of NALMA occurs at higher timescales, with respect to the rotation of NAGMA; both processes are significantly slower than the structural dynamics of hydration water, suggesting that solute and solvent motions are uncoupled. Finally, our results do not indicate the presence of super-slow water (relaxation times in the order of tens of picoseconds) around the peptides investigated. Full article

(This article belongs to the Special Issue How Cosolvents and Cosolutes Affect Biomolecules Stability and Activity)

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15 pages, 3081 KiB

Open AccessEditor’s ChoiceArticle

The Possible Role of the Type I Chaperonins in Human Insulin Self-Association

by Federica Pizzo, Maria Rosalia Mangione, Fabio Librizzi, Mauro Manno, Vincenzo Martorana, Rosina Noto and Silvia Vilasi

Life 2022, 12(3), 448; https://doi.org/10.3390/life12030448 - 18 Mar 2022

Viewed by 2000

Abstract

Insulin is a hormone that attends to energy metabolism by regulating glucose levels in the bloodstream. It is synthesised within pancreas beta-cells where, before being released into the serum, it is stored in granules as hexamers coordinated by Zn²⁺ and further packaged [...] Read more.

Insulin is a hormone that attends to energy metabolism by regulating glucose levels in the bloodstream. It is synthesised within pancreas beta-cells where, before being released into the serum, it is stored in granules as hexamers coordinated by Zn²⁺ and further packaged in microcrystalline structures. The group I chaperonin cpn60, known for its assembly-assisting function, is present, together with its cochaperonin cpn10, at each step of the insulin secretory pathway. However, the exact function of the heat shock protein in insulin biosynthesis and processing is still far from being understood. Here we explore the possibility that the molecular machine cpn60/cpn10 could have a role in insulin hexameric assembly and its further crystallization. Moreover, we also evaluate their potential protective effect in pathological insulin aggregation. The experiments performed with the cpn60 bacterial homologue, GroEL, in complex with its cochaperonin GroES, by using spectroscopic methods, microscopy and hydrodynamic techniques, reveal that the chaperonins in vitro favour insulin hexameric organisation and inhibit its aberrant aggregation. These results provide new details in the field of insulin assembly and its related disorders. Full article

(This article belongs to the Special Issue How Cosolvents and Cosolutes Affect Biomolecules Stability and Activity)

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13 pages, 2624 KiB

Open AccessArticle

A Rationalization of the Effect That TMAO, Glycine, and Betaine Exert on the Collapse of Elastin-like Polypeptides

by Andrea Pica and Giuseppe Graziano

Life 2022, 12(2), 140; https://doi.org/10.3390/life12020140 - 18 Jan 2022

Cited by 1 | Viewed by 1175

Abstract

Elastin-like polypeptides (ELPs) are soluble in water at low temperature, but, on increasing the temperature, they undergo a reversible and cooperative, coil-to-globule collapse transition. It has been shown that the addition to water of either trimethylamine N-oxide (TMAO), glycine, or betaine causes [...] Read more.

Elastin-like polypeptides (ELPs) are soluble in water at low temperature, but, on increasing the temperature, they undergo a reversible and cooperative, coil-to-globule collapse transition. It has been shown that the addition to water of either trimethylamine N-oxide (TMAO), glycine, or betaine causes a significant decrease of T(collapse) in the case of a specific ELP. Traditional rationalizations of these phenomena do not work in the present case. We show that an alternative approach, grounded in the magnitude of the solvent-excluded volume effect and its temperature dependence (strictly linked to the translational entropy of solvent and co-solute molecules), is able to rationalize the occurrence of ELP collapse in water on raising the temperature, as well as the T(collapse) lowering caused by the addition to water of either TMAO, glycine, or betaine. Full article

(This article belongs to the Special Issue How Cosolvents and Cosolutes Affect Biomolecules Stability and Activity)

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18 pages, 630 KiB

Open AccessArticle

Taurine Stabilizing Effect on Lysozyme

by Leonardo Mastrella, Paolo Moretti, Silvia Pieraccini, Simona Magi, Silvia Piccirillo and Maria Grazia Ortore

Life 2022, 12(1), 133; https://doi.org/10.3390/life12010133 - 17 Jan 2022

Cited by 5 | Viewed by 2882

Abstract

Taurine is an important organic osmolyte in mammalian cells, and it weakens inflammation and oxidative stress mediated injuries in some diseases. Recently, taurine has been demonstrated to play a therapeutic role against neurodegenerative disorders, although its parallel involvement in several biochemical mechanisms makes [...] Read more.

Taurine is an important organic osmolyte in mammalian cells, and it weakens inflammation and oxidative stress mediated injuries in some diseases. Recently, taurine has been demonstrated to play a therapeutic role against neurodegenerative disorders, although its parallel involvement in several biochemical mechanisms makes not clear taurine specific role in these diseases. Furthermore, the stabilizing effect of this molecule in terms of protein stability is known, but not deeply investigated. In this work we explore by Circular Dichroism the stabilizing impact of taurine in lysozyme thermal denaturation and its influence in lysozyme aggregation into amyloid fibrils. Taurine even at low concentration modifies protein-protein interactions in lysozyme native state, as revealed by Small Angle X-ray Scattering experiments, and alters the amyloid aggregation pattern without completely inhibiting it, as confirmed by UV/Vis spectroscopy with Congo Red and by Atomic Force Microscopy. Evaluation of the cytotoxicities of the amyloid fibrils grown in presence or in absence of taurine is investigated on SH-SY5Y neuroblastoma cells. Full article

(This article belongs to the Special Issue How Cosolvents and Cosolutes Affect Biomolecules Stability and Activity)

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25 pages, 2467 KiB

Open AccessArticle

SAXS Reveals the Stabilization Effects of Modified Sugars on Model Proteins

by Astra Piccinini, Eva C. Lourenço, Osvaldo S. Ascenso, Maria Rita Ventura, Heinz Amenitsch, Paolo Moretti, Paolo Mariani, Maria Grazia Ortore and Francesco Spinozzi

Life 2022, 12(1), 123; https://doi.org/10.3390/life12010123 - 15 Jan 2022

Cited by 3 | Viewed by 2223

Abstract

Many proteins are usually not stable under different stresses, such as temperature and pH variations, mechanical stresses, high concentrations, and high saline contents, and their transport is always difficult, because they need to be maintained in a cold regime, which is costly and [...] Read more.

Many proteins are usually not stable under different stresses, such as temperature and pH variations, mechanical stresses, high concentrations, and high saline contents, and their transport is always difficult, because they need to be maintained in a cold regime, which is costly and very challenging to achieve in remote areas of the world. For this reason, it is extremely important to find stabilizing agents that are able to preserve and protect proteins against denaturation. In the present work, we investigate, by extensively using synchrotron small-angle X-ray scattering experiments, the stabilization effect of five different sugar-derived compounds developed at ExtremoChem on two model proteins: myoglobin and insulin. The data analysis, based on a novel method that combines structural and thermodynamic features, has provided details about the physical-chemical processes that regulate the stability of these proteins in the presence of stabilizing compounds. The results clearly show that some modified sugars exert a greater stabilizing effect than others, being able to maintain the active forms of proteins at temperatures higher than those in which proteins, in the absence of stabilizers, reach denatured states. Full article

(This article belongs to the Special Issue How Cosolvents and Cosolutes Affect Biomolecules Stability and Activity)

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16 pages, 3629 KiB

Open AccessArticle

Conformational Consequences for Compatible Osmolytes on Thermal Denaturation

by Nimesh Shukla, Brianna Bembenek, Erika A. Taylor and Christina M. Othon

Life 2021, 11(12), 1394; https://doi.org/10.3390/life11121394 - 13 Dec 2021

Viewed by 2054

Abstract

Compatible osmolytes are a broad class of small organic molecules employed by living systems to combat environmental stress by enhancing the native protein structure. The molecular features that make for a superior biopreservation remain elusive. Through the use of time-resolved and steady-state spectroscopic [...] Read more.

Compatible osmolytes are a broad class of small organic molecules employed by living systems to combat environmental stress by enhancing the native protein structure. The molecular features that make for a superior biopreservation remain elusive. Through the use of time-resolved and steady-state spectroscopic techniques, in combination with molecular simulation, insight into what makes one molecule a more effective compatible osmolyte can be gained. Disaccharides differing only in their glycosidic bonds can exhibit different degrees of stabilization against thermal denaturation. The degree to which each sugar is preferentially excluded may explain these differences. The present work examines the biopreservation and hydration of trehalose, maltose, and gentiobiose. Full article

(This article belongs to the Special Issue How Cosolvents and Cosolutes Affect Biomolecules Stability and Activity)

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14 pages, 2693 KiB

Open AccessArticle

Protein Hydration in a Bioprotecting Mixture

by Silvia Corezzi, Brenda Bracco, Paola Sassi, Marco Paolantoni and Lucia Comez

Life 2021, 11(10), 995; https://doi.org/10.3390/life11100995 - 22 Sep 2021

Cited by 6 | Viewed by 1669

Abstract

We combined broad-band depolarized light scattering and infrared spectroscopies to study the properties of hydration water in a lysozyme-trehalose aqueous solution, where trehalose is present above the concentration threshold (30% in weight) relevant for biopreservation. The joint use of the two different techniques, [...] Read more.

We combined broad-band depolarized light scattering and infrared spectroscopies to study the properties of hydration water in a lysozyme-trehalose aqueous solution, where trehalose is present above the concentration threshold (30% in weight) relevant for biopreservation. The joint use of the two different techniques, which were sensitive to inter-and intra-molecular degrees of freedom, shed new light on the molecular mechanism underlying the interaction between the three species in the mixture. Thanks to the comparison with the binary solution cases, we were able to show that, under the investigated conditions, the protein, through preferential hydration, remains strongly hydrated even in the ternary mixture. This supported the water entrapment scenario, for which a certain amount of water between protein and sugar protects the biomolecule from damage caused by external agents. Full article

(This article belongs to the Special Issue How Cosolvents and Cosolutes Affect Biomolecules Stability and Activity)

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13 pages, 2650 KiB

Open AccessArticle

Hydrogen Bonding and Solvation of a Proline-Based Peptide Model in Salt Solutions

by Sara Catalini, Barbara Rossi, Mariagrazia Tortora, Paolo Foggi, Alessandro Gessini, Claudio Masciovecchio and Fabio Bruni

Life 2021, 11(8), 824; https://doi.org/10.3390/life11080824 - 12 Aug 2021

Cited by 3 | Viewed by 2221

Abstract

The hydrogen bonding of water and water/salt mixtures around the proline-based tripeptide model glycyl-l-prolyl-glycinamide·HCl (GPG-NH₂) is investigated here by multi-wavelength UV resonance Raman spectroscopy (UVRR) to clarify the role of ion–peptide interactions in affecting the conformational stability of this [...] Read more.

The hydrogen bonding of water and water/salt mixtures around the proline-based tripeptide model glycyl-l-prolyl-glycinamide·HCl (GPG-NH₂) is investigated here by multi-wavelength UV resonance Raman spectroscopy (UVRR) to clarify the role of ion–peptide interactions in affecting the conformational stability of this peptide. The unique sensitivity and selectivity of the UVRR technique allow us to efficiently probe the hydrogen bond interaction between water molecules and proline residues in different solvation conditions, along with its influence on trans to cis isomerism in the hydrated tripeptide. The spectroscopic data suggest a relevant role played by the cations in altering the solvation shell at the carbonyl site of proline_., while the fluoride and chloride anions were found to promote the establishment of the strongest interactions on the

C = O

site of proline. This latter effect is reflected in the greater stabilization of the trans conformers of the tripeptide in the presence of these specific ions. The molecular view provided by UVRR experiments was complemented by the results of circular dichroism (CD) measurements that show a strong structural stabilizing effect on the β-turn motif of GPG-NH₂ observed in the presence of KF as a co-solute. Full article

(This article belongs to the Special Issue How Cosolvents and Cosolutes Affect Biomolecules Stability and Activity)

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16 pages, 1972 KiB

Open AccessArticle

General Counteraction Exerted by Sugars against Denaturants

by Serena Cozzolino, Attila Tortorella, Pompea Del Vecchio and Giuseppe Graziano

Life 2021, 11(7), 652; https://doi.org/10.3390/life11070652 - 04 Jul 2021

Cited by 5 | Viewed by 2024

Abstract

The conformational stability of globular proteins is strongly influenced by the addition to water of different co-solutes. Some of the latter destabilize the native state, while others stabilize it. It is emerging that stabilizing agents are able to counteract the action of destabilizing [...] Read more.

The conformational stability of globular proteins is strongly influenced by the addition to water of different co-solutes. Some of the latter destabilize the native state, while others stabilize it. It is emerging that stabilizing agents are able to counteract the action of destabilizing agents. We have already provided experimental evidence that this counteraction is a general phenomenon and offered a rationalization. In the present work, we show that four different sugars, namely fructose, glucose, sucrose, and trehalose, counteract the effect of urea, tetramethylurea, sodium perchlorate, guanidinium chloride, and guanidinium thiocyanate despite the chemical and structural differences of those destabilizing agents. The rationalization we provide is as follows: (a) the solvent-excluded volume effect, a purely entropic effect, stabilizes the native state, whose solvent-accessible surface area is smaller than the one of denatured conformations; (b) the magnitude of the solvent-excluded volume effect increases markedly in ternary solutions because the experimental density of such solutions is larger than that of pure water. Full article

(This article belongs to the Special Issue How Cosolvents and Cosolutes Affect Biomolecules Stability and Activity)

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