Thermodynamic analysis of osmolyte effect on thermal stability of ribonuclease A in terms of water activity

Boosting Fructosyl Transferase's Thermostability and Catalytic Performance for Highly Efficient Fructooligosaccharides (FOS) Production

Achieving enzymatic food processing at high substrate concentrations can significantly enhance production efficiency; however, related studies are notably insufficient. This study focused on the enzymatic synthesis of fructooligosaccharides (FOS) at high temperature and high substrate concentration. Results revealed that increased viscosity and limited substrate solubility in high-concentration systems could be alleviated by raising the reaction temperature, provided it aligned with the enzyme's thermostability. Further analysis of enzyme thermostability in real sucrose solutions demonstrates that the enzyme's thermostability was remarkedly improved at higher sucrose concentrations, evidenced by a 10.3 °C increase in melting temperature (Tm) in an 800 g/L sucrose solution. Building upon these findings, we developed a novel method for enzymatic FOS synthesis at elevated temperatures and high sucrose concentrations. Compared to existing commercial methods, the initial transglycosylation rate and volumetric productivity for FOS synthesis increased by 155.9% and 113.5%, respectively, at 65 °C in an 800 g/L sucrose solution. This study underscores the pivotal role of substrate concentration, incubation temperature, and the enzyme's actual status in advancing enzyme-catalyzed processes and demonstrates the potential of enzymatic applications in enhancing food processing technologies, providing innovative strategies for the food industry.

Stability of Protein Pharmaceuticals: Recent Advances

There have been significant advances in the formulation and stabilization of proteins in the liquid state over the past years since our previous review. Our mechanistic understanding of protein-excipient interactions has increased, allowing one to develop formulations in a more rational fashion. The field has moved towards more complex and challenging formulations, such as high concentration formulations to allow for subcutaneous administration and co-formulation. While much of the published work has focused on mAbs, the principles appear to apply to any therapeutic protein, although mAbs clearly have some distinctive features. In this review, we first discuss chemical degradation reactions. This is followed by a section on physical instability issues. Then, more specific topics are addressed: instability induced by interactions with interfaces, predictive methods for physical stability and interplay between chemical and physical instability. The final parts are devoted to discussions how all the above impacts (co-)formulation strategies, in particular for high protein concentration solutions.'

Interaction of lectin Sambucus nigra with sialylated trisaccharides in the presence of osmolytes. Chronopotentiometric sensing

Trisaccharides bind to their interaction partners-lectins relatively weakly, which makes detection of their complexes challenging. In this work, we show that an osmolyte presence improves the distinguishing complexes of lectin Sambucus nigra with trisialyllactoses with various binding affinities. The addition of osmolyte, non-binding sugar mannose significantly improved the precision of binding experiments performed using chronopotentiometric stripping at the electrode surface and fluorescence analysis in solution. Osmolytes minimized nonspecific interactions between binding sugar and lectin. Obtained findings can be utilized in any in vitro methods studying interactions of carbohydrates, respectively their conjugates with proteins. The study of carbohydrate interactions appears important since they play essential roles in a variety of biological processes including carcinogenesis.

The Role of Taurine in Skeletal Muscle Functioning and Its Potential as a Supportive Treatment for Duchenne Muscular Dystrophy

Taurine (2-aminoethanesulfonic acid) is required for ensuring proper muscle functioning. Knockout of the taurine transporter in mice results in low taurine concentrations in the muscle and associates with myofiber necrosis and diminished exercise capacity. Interestingly, regulation of taurine and its transporter is altered in the mdx mouse, a model for Duchenne Muscular Dystrophy (DMD). DMD is a genetic disorder characterized by progressive muscle degeneration and weakness due to the absence of dystrophin from the muscle membrane, causing destabilization and contraction-induced muscle cell damage. This review explores the physiological role of taurine in skeletal muscle and the consequences of a disturbed balance in DMD. Its potential as a supportive treatment for DMD is also discussed. In addition to genetic correction, that is currently under development as a curative treatment, taurine supplementation has the potential to reduce muscle inflammation and improve muscle strength in patients.

On the Aggregation and Nucleation Mechanism of the Monoclonal Antibody Anti-CD20 Near Liquid-Liquid Phase Separation (LLPS)

The crystallization of Anti-CD20, a full-length monoclonal antibody, has been studied in the PEG400/Na2SO4/Water system near Liquid-Liquid Phase Separation (LLPS) conditions by both sitting-drop vapour diffusion and batch methods. In order to understand the Anti-CD20 crystallization propensity in the solvent system of different compositions, we investigated some measurable parameters, normally used to assess protein conformational and colloidal stability in solution, with the aim to understand the aggregation mechanism of this complex biomacromolecule. We propose that under crystallization conditions a minor population of specifically aggregated protein molecules are present. While this minor species hardly contributes to the measured average solution behaviour, it induces and promotes crystal formation. The existence of this minor species is the result of the LLPS occurring concomitantly under crystallization conditions.

Effect of osmolytes on in-vitro aggregation properties of peptides derived from TGFBIp

Protein aggregation has been one of the leading triggers of various disease conditions, such as Alzheimer’s, Parkinson’s and other amyloidosis. TGFBI-associated corneal dystrophies are protein aggregation disorders in which the mutant TGFBIp aggregates and accumulates in the cornea, leading to a reduction in visual acuity and blindness in severe cases. Currently, the only therapy available is invasive and there is a known recurrence after surgery. In this study, we tested the inhibitory and amyloid dissociation properties of four osmolytes in an in-vitroTGFBI peptide aggregation model. The 23-amino acid long peptide (TGFBIp 611–633 with the mutation c.623 G>R) from the 4th FAS-1 domain of TGFBIp that rapidly forms amyloid fibrils was used in the study. Several biophysical methods like Thioflavin T (ThT) fluorescence, Circular Dichroism (CD), fluorescence microscopy and Transmission electron microscopy (TEM) were used to study the inhibitory and amyloid disaggregation properties of the four osmolytes (Betaine, Raffinose, Sarcosine, and Taurine). The osmolytes were effective in both inhibiting and disaggregating the amyloid fibrils derived from TGFBIp 611–633 c.623 G>R peptide. The osmolytes did not have an adverse toxic effect on cultured human corneal fibroblast cells and could potentially be a useful therapeutic strategy for patients with TGFBIp corneal dystrophies.

Distinctive behavior and two-dimensional vibrational dynamics of water molecules inside glycine solvation shell

We present a first principles molecular dynamics study of a deuterated aqueous solution of a single glycine moiety to explore the structure, dynamics, and two-dimensional infrared spectra of water molecules found in the solvation shell of glycine.

Solution thermodynamic approach to analyze protein stability in aqueous solutions

Protein thermal stability was analyzed by a solution thermodynamic approach. The small energetic differences in hydrogen-bonds (HB) among amino acid resdues and water molecules were proved to be amplified by the large number of HB involved to bring about the equilibrium shift from folding to unfolding of proteins. In aqueous solutions, water activity (A_w) plays a key role in protein stability. Therefore, A_w was precisely determined for various solutions and its relationship with solution structure was discussed. Wyman-Tanford analysis based on A_w showed linear regressions, without exception, between protein unfolding-ratio and A_w for lysozyme, ribonuclease A, and α-chymotrypsinogen A in various solutions with sugars, osmolytes, alcohols, and protein denaturant. From this linear regression, the free energy difference, ΔΔG, for a protein in a solution and in pure water, was easily obtained. Protein stability in a solution was proved to be determined by a balance between hydration and solute-binding effects to the protein and also by solution structure, which indirectly affects the hydrophobic interaction in a protein molecule. Temperature dependence of HB on protein stability suggested its interrelationship with hydrophobic interaction.

Science and art of protein formulation development

Protein pharmaceuticals have become a significant class of marketed drug products and are expected to grow steadily over the next decade. Development of a commercial protein product is, however, a rather complex process. A critical step in this process is formulation development, enabling the final product configuration. A number of challenges still exist in the formulation development process. This review is intended to discuss these challenges, to illustrate the basic formulation development processes, and to compare the options and strategies in practical formulation development.

Biophysical Spandrels form a Hot-Spot for Kosmotropic Mutations in Bacteriophage Thermal Adaptation

Temperature plays a dominating role in protein structure and function, and life has evolved myriad strategies to adapt proteins to environmental thermal stress. Cellular systems can utilize kosmotropic osmolytes, the products of complex biochemical pathways, to act as chemical chaperones. These extrinsic molecules, e.g., trehalose, alter local water structure to modulate the strength of the hydrophobic effect and increase protein stability. In contrast, simpler genetic systems must rely on intrinsic mutation to affect protein stability. In naturally occurring microvirid bacteriophages of the subfamily Bullavirinae, capsid stability is randomly distributed across the phylogeny, suggesting it is not phylogenetically linked and could be altered through adaptive mutation. We hypothesized that these phages could utilize an adaptive mechanism that mimics the stabilizing effects of the kosmotrope trehalose through mutation. Kinetic stability of wild-type ID8, a relative of ΦX174, displays a saturable response to trehalose. Thermal adaptation mutations in ID8 improve capsid stability and reduce responsiveness to trehalose suggesting the mutations move stability closer to the kosmotropic saturation point, mimicking the kosmotropic effect of trehalose. These mutations localize to and modulate the hydrophobicity of a cavern formation at the interface of phage coat and spike proteins-an evolutionary spandrel. Across a series of genetically distinct phages, responsiveness to trehalose correlates positively with cavern hydrophobicity suggesting that the level of hydrophobicity of the cavern may provide a biophysical gating mechanism constraining or permitting adaptation in a lineage-specific manner. Our results demonstrate that a single mutation can exploit pre-existing, non-adaptive structural features to mimic the adaptive effects of complex biochemical pathways.

Stabilization of Bacillus circulans xylanase by combinatorial insertional fusion to a thermophilic host protein

High thermostability of an enzyme is critical for its industrial application. While many engineering approaches such as mutagenesis have enhanced enzyme thermostability, they often suffer from reduced enzymatic activity. A thermally stabilized enzyme with unchanged amino acids is preferable for subsequent functional evolution necessary to address other important industrial needs. In the research presented here, we applied insertional fusion to a thermophilic maltodextrin-binding protein from Pyrococcus furiosus (PfMBP) in order to improve the thermal stability of Bacillus circulans xylanase (BCX). Specifically, we used an engineered transposon to construct a combinatorial library of randomly inserted BCX into PfMBP. The library was then subjected to functional screening to identify successful PfMBP-BCX insertion complexes, PfMBP-BCX161 and PfMBP-BCX165, displaying substantially improved kinetic stability at elevated temperatures compared to unfused BCX and other controls. Results from subsequent characterizations were consistent with the view that lowered aggregation of BCX and reduced conformational flexibility at the termini was responsible for increased thermal stability. Our stabilizing approach neither sacrificed xylanase activity nor required changes in the BCX amino acid sequence. Overall, the current study demonstrated the benefit of combinatorial insertional fusion to PfMBP as a systematic tool for the creation of enzymatically active and thermostable BCX variants.

Counteraction of lactose on the thermal stability and activity of α-chymotrypsin: thermodynamic, kinetic and docking studies

Stabilized aqueous solutions of α-chymotrypsin have a therapeutic utility in the treatment of certain forms of asthma, bronchitis, rhinitis, sinusitis, as well as certain dermatological conditions such as leg ulcers and ringworm.

Analysis of Eisenia fetida earthworm responses to sub-lethal C60 nanoparticle exposure using (1)H-NMR based metabolomics

The enhanced production and environmental release of Buckminsterfullerene (C60) nanoparticles will likely increase the exposure and risk to soil dwelling organisms. We used (1)H NMR-based metabolomics to investigate the response of Eisenia fetida earthworms to sub-lethal C60 nanoparticle exposure in both contact and soil tests. Principal component analysis of (1)H NMR data showed clear separation between controls and exposed earthworms after just 2 days of exposure, however as exposure time increased the separation decreased in soil but increased in contact tests suggesting potential adaptation during soil exposure. The amino acids leucine, valine, isoleucine and phenylalanine, the nucleoside inosine, and the sugars glucose and maltose emerged as potential bioindicators of exposure to C60 nanoparticles. The significant responses observed in earthworms using NMR-based metabolomics after exposure to very low concentrations of C60 nanoparticles suggests the need for further investigations to better understand and predict their sub-lethal toxicity.

Cosolute effects on amyloid aggregation in a nondiffusion limited regime: intrinsic osmolyte properties and the volume exclusion principle

The effects of cosolutes on amyloid aggregation kinetics in vivo are critical and not fully understood. To explore the effects of cosolute additives, the in vitro behavior of destabilizing and stabilizing osmolytes with polymer cosolutes on the aggregation of a model amyloid, human insulin, is probed using experiments coupled with an amyloid aggregation reaction model. The destabilizing osmolyte, guanidine hydrochloride (GuHCl), induces biphasic behavior on the amyloid aggregation rate exhibited by an enhancement of the aggregation kinetics at low concentrations of GuHCl (<0.6 M) and a reduction in kinetics at higher GuHCl concentrations. Stabilizing osmolytes, glycerol, sorbitol and trimethylamine N-oxide, slow the rate of aggregation by reducing the rate of monomer unfolding. Polymer cosolutes, polyvinylpyrrolidone 3.5 kDa and 40 kDa, delay amyloid aggregation mainly through a decrease in the nucleation reaction. These results are in good agreement with the volume exclusion principle for polymer crowding and supports the need to include conformational rearrangement of monomers prior to nucleation. Using fluorescence correlation spectroscopy, we demonstrate that amyloid aggregation is nondiffusion limited, except during fibril accumulation in the presence of high concentrations of long chain polymers. Lastly, the neutral surface area of osmolytes correlates well with the time to initiate fibril formation, tlag, which implicates an intrinsic osmolyte property underlying preferential interactions.

Effects of osmolytes on protein-solvent interactions in crowded environment: Analyzing the effect of TMAO on proteins in crowded solutions

We analyzed the effect of a natural osmolyte, trimethylamine N-oxide (TMAO), on structural properties and conformational stabilities of several proteins under macromolecular crowding conditions by a set of biophysical techniques. We also used the solvent interaction analysis method to look at the peculiarities of the TMAO-protein interactions under crowded conditions. To this end, we analyzed the partitioning of these proteins in TMAO-free and TMAO-containing aqueous two-phase systems (ATPSs). These ATPSs had the same polymer composition of 6.0 wt.% PEG-8000 and 12.0 wt.% dextran-75, and same ionic composition of 0.01 M K/NaPB, pH 7.4. These analyses revealed that there is no direct interaction of TMAO with proteins, suggesting that the TMAO effects on the protein structure in crowded solutions occur via the effects of this osmolyte on solvent properties of aqueous media. The effects of TMAO on protein structure in the presence of polymers were rather complex and protein-specific. Curiously, our study revealed that in highly concentrated polymer solutions, TMAO does not always act to promote further protein folding.

Are stabilizing osmolytes preferentially excluded from the protein surface? FTIR and MD studies

Stabilizing osmolytes are not always preferentially excluded and can interact with the protein surface in two ways: indirectly or directly.