Intrinsic tryptophan fluorescence in the detection and analysis of proteins: a focus on Förster resonance energy transfer techniques

Encountering and Wrestling: Neutrophils Recognize and Defensively Degrade Graphene Oxide

The boosting exploitation of graphene oxide (GO) increases exposure risk to human beings. However, as primary defender in the first immune line, neutrophils' mechanism of defensive behavior toward GO remains unclear. Herein, we discovered that neutrophils recognize and defensively degrade GO in a lateral dimension dependent manner. The micrometer-sized GO (mGO) induces NETosis by releasing neutrophil extracellular traps (NETs), while nanometer-sized GO (nGO) elicits neutrophil degranulation. The two neutrophils' defensive behaviors are accompanied with generation of reactive oxygen species and activation of p-ERK and p-Akt kinases. However, mGO-induced NETosis is NADPH oxidase (NOX)-independent while nGO-triggered degranulation is NOX-dependent. Furthermore, myeloperoxidase (MPO) is determinant mediator despite distinct neutrophil phenotypes. Neutrophils release NETs comprising of MPO upon activated with mGO, while MPO is secreted via nGO-induced degranulation. Moreover, the binding energy between MPO and GO is calculated to be 69.8728 kJ mol^-1 , indicating that electrostatic interactions mainly cause the spontaneous binding process. Meanwhile, the central enzymatic biodegradation occurs at oxygenic active sites and defects on GO. Mass spectrometry analysis deciphers the degradation products are biocompatible molecules like flavonoids and polyphenols. This study provides fundamental evidence and practical guidance for nanotechnology based on GO, including vaccine adjuvant, implantable devices, and energy storage.

A comprehensive review on LED-induced fluorescence in diagnostic pathology

Sensitivity, specificity, mobility, and affordability are important criteria to consider for developing diagnostic instruments in common use. Fluorescence spectroscopy has been demonstrating substantial potential in the clinical diagnosis of diseases and evaluating the underlying causes of pathogenesis. A higher degree of device integration with appropriate sensitivity and reasonable cost would further boost the value of the fluorescence techniques in clinical diagnosis and aid in the reduction of healthcare expenses, which is a key economic concern in emerging markets. Light-emitting diodes (LEDs), which are inexpensive and smaller are attractive alternatives to conventional excitation sources in fluorescence spectroscopy, are gaining a lot of momentum in the development of affordable, compact analytical instruments of clinical relevance. The commercial availability of a broad range of LED wavelengths (255-4600 nm) has opened up new avenues for targeting a wide range of clinically significant molecules (both endogenous and exogenous), thereby diagnosing a range of clinical illnesses. As a result, we have specifically examined the uses of LED-induced fluorescence (LED-IF) in preclinical and clinical evaluations of pathological conditions, considering the present advancements in the field.

The Plasma Levels of 3-Hydroxybutyrate, Dityrosine, and Other Markers of Oxidative Stress and Energy Metabolism in Major Depressive Disorder

Major depressive disorder (MDD) is a serious mental disease with a pathophysiology that is not yet fully clarified. An increasing number of studies show an association of MDD with energy metabolism alteration and the presence of oxidative stress. We aimed to evaluate plasma levels of 3-hydroxybutyrate (3HB), NADH, myeloperoxidase, and dityrosine (di-Tyr) in adolescent and adult patients with MDD, compare them with healthy age-matched controls, and assess the effect of antidepressant treatment during hospitalisation on these levels. In our study, plasmatic levels of 3HB were elevated in both adolescents (by 55%; p = 0.0004) and adults (by 88%; p < 0.0001) with MDD compared to controls. Levels of dityrosine were increased in MDD adults (by 19%; p = 0.0092) but not adolescents. We have not found any significant effect of antidepressants on the selected parameters during the short observation period. Our study supports the findings suggesting altered energy metabolism in MDD and demonstrates its presence independently of the age of the patients.

Comparison of the stability of CYP105A1 and its variants engineered for production of active forms of vitamin D

CYP105A1 from Streptomyces griseolus converts vitamin D3 to its biologically active form, 1α,25-dihydroxy vitamin D3. R73A/R84A mutation enhanced the 1α- and 25-hydroxylation activity for vitamin D3, while M239A mutation generated the 1α-hydroxylation activity for vitamin D2. In this study, the stability of six CYP105A1 enzymes, including 5 variants (R73A/R84A, M239A, R73A/R84A/M239A (=TriA), TriA/E90A, and TriA/E90D), was examined. Circular dichroism analysis revealed that M239A markedly reduces the enzyme stability. Protein fluorescence analysis disclosed that these mutations, especially M239A, induce large changes in the local conformation around Trp residues. Strong stabilizing effect of glycerol was observed. Nondenaturing PAGE analysis showed that CYP105A1 enzymes are prone to self-association. Fluorescence analysis using a hydrophobic probe 8-anilino-1-naphthalenesulfonic acid suggested that M239A mutation enhances self-association and that E90A and E90D mutations, in cooperation with M239A, accelerate self-association with little effect on the stability.

Discovery of calcium-binding peptides derived from defatted lemon basil seeds with enhanced calcium uptake in human intestinal epithelial cells, Caco-2

It is anticipated that calcium-chelating peptides may serve to enhance the absorption of calcium. This research examined defatted lemon basil seeds (DLBS) which had been treated with Alcalase under optimized parameters for the degree of hydrolysis for proteolysis, discovering that the activity for calcium-binding in a competitive condition with phosphate ion was 60.39 ± 1.545%. The purification of the hydrolysates was performed via ultrafiltration along with reversed-phase high performance liquid chromatography (RP-HPLC). Determination of the purified peptide amino acid sequence was confirmed for both peptides and reported as Ala-Phe-Asn-Arg-Ala-Lys-Ser-Lys-Ala-Leu-Asn-Glu-Asn (AFNRAKSKALNEN; Basil-1), and Tyr-Asp-Ser-Ser-Gly-Gly-Pro-Thr-Pro-Trp-Leu-Ser-Pro-Tyr (YDSSGGPTPWLSPY; Basil-2). The respective activities for calcium-binding were 38.62 ± 1.33%, and 42.19 ± 2.27%. Fluorescence spectroscopy, and fourier transform infrared spectroscopy were employed in order to assess the chelating mechanism between calcium and the peptides. It was found that the calcium ions took place through the activity of the amino nitrogen atoms and the oxygen atoms on the carboxyl group. Moreover, both of these peptides served to improve calcium transport and absorption in Caco-2 cell monolayers, depending on the concentration involved. It was revealed that the peptide-calcium complexes offered an increased calcium absorption percentage when compared to free calcium at similar concentrations. It might be concluded that the peptide within the peptide-calcium complex can promote calcium absorption through both active and passive transport pathways by increasing calcium concentration and promoting cell membrane interaction. Accordingly, DLBS protein can be considered a strong potential source of protein which can be used to produce calcium-binding peptides and might therefore play a role in the production of nutraceutical foods as a bioactive ingredient.

Sequence-specific destabilization of azurin by tetramethylguanidinium-dipeptide ionic liquids

The thermal unfolding of the copper redox protein azurin was studied in the presence of four different dipeptide-based ionic liquids (ILs) utilizing tetramethylguanidinium as the cation. The four dipeptides have different sequences including the amino acids Ser and Asp: TMG-AspAsp, TMG-SerSer, TMG-SerAsp, and TMG-AspSer. Thermal unfolding curves generated from temperature-dependent fluorescence spectroscopy experiments showed that TMG-AspAsp and TMG-SerSer have minor destabilizing effects on the protein while TMG-AspSer and TMG-SerAsp strongly destabilize azurin. Red-shifted fluorescence signatures in the 25 °C correlate with the observed protein destabilization in the solutions with TMG-AspSer and TMG-SerAsp. These signals could correspond to interactions between the Asp residue in the dipeptide and the azurin Trp residue in the unfolded state. These results, supported by appropriate control experiments, suggest that dipeptide sequence-specific interactions lead to selective protein destabilization and motivate further studies of TMG-dipeptide ILs.

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Four different dipeptide-based ionic liquids were prepared with TMG as cation.

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The dipeptides included all four sequences containing Asp and Ser.

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The ionic liquids destabilizing effects on the protein azurin were measured.

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Different dipeptide sequences have different effects on the protein stability.

The Study of Protein-Cyclitol Interactions

Investigation of interactions between the target protein molecule and ligand allows for an understanding of the nature of the molecular recognition, functions, and biological activity of protein–ligand complexation. In the present work, non-specific interactions between a model protein (Bovine Serum Albumin) and four cyclitols were investigated. D-sorbitol and adonitol represent the group of linear-structure cyclitols, while shikimic acid and D-(–)-quinic acid have cyclic-structure molecules. Various analytical methods, including chromatographic analysis (HPLC-MS/MS), electrophoretic analysis (SDS-PAGE), spectroscopic analysis (spectrofluorimetry, Fourier transform infrared spectroscopy, and Raman spectroscopy), and isothermal titration calorimetry (ITC), were applied for the description of protein–cyclitol interactions. Additionally, computational calculations were performed to predict the possible binding places. Kinetic studies allowed us to clarify interaction mechanisms that may take place during BSA and cyclitol interaction. The results allow us, among other things, to evaluate the impact of the cyclitol’s structure on the character of its interactions with the protein.

Evaluating the interaction of human serum albumin (HSA) and 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) liposomes in different aqueous environments using anisotropy resolved multi-dimensional emission spectroscopy (ARMES)

Studying the interaction between plasma proteins and liposomes is critical, particularly for their use as drug delivery systems. Here, the efficacy of anisotropy resolved multidimensional emission spectroscopy (ARMES) for investigating the interaction of human serum albumin (HSA) with liposomes was explored and compared to conventional spectroscopic techniques. Dynamic Light Scattering (DLS) and absorbance spectroscopy (with Multivariate Curve Resolution (MCR) modeling) indicated that the highest degree of liposome rupturing, and aggregation occurred in water, with less in ammonium bicarbonate buffer (ABC) and phosphate buffered saline (PBS). Fluorescence emission spectra of HSA-liposome mixtures revealed significant hypsochromic shifts for water and ABC, but much less in PBS, where the data suggests a non-penetrating protein layer was formed. Average fluorescence lifetimes decreased upon liposome interaction in water (6.2→5.2 ns) and ABC buffer (6.3→5.6 ns) but increased slightly for PBS (5.6→5.8 ns). ARMES using polarized Total Synchronous Fluorescence Scan measurements with parallel factor (PARAFAC) analysis resolved intrinsic HSA fluorescence into two components for interactions in water and ABC buffer, but only one component for PBS. These components, in water and ABC buffer, corresponded to two different HSA populations, one blue-shifted and penetrating the liposomes (λ_ex/em = ~ 280/320 nm) and a second, similar to free HSA in solution (λ_ex/em = ~ 282/356 nm). PARAFAC scores for water and ABC buffer suggested that a large proportion of HSA interacted in an end on configuration. ARMES provides a new way for investigating protein-liposome interactions that exploits the full intrinsic emission space of the protein and thus avoids the use of extrinsic labels. The use of multivariate data analysis provided a comprehensive and structured framework to extract a variety of useful information (resolving different fluorescent species, quantifying their signal contribution, and extracting light scatter signals) all of which can be used to discriminate between interaction mechanisms.

Biomaterials via peptide assembly: Design, characterization, and application in tissue engineering

A core challenge in biomaterials, with both fundamental significance and technological relevance, concerns the rational design of bioactive microenvironments. Designed properly, peptides can undergo supramolecular assembly into dynamic, physical hydrogels that mimic the mechanical, topological, and biochemical features of native tissue microenvironments. The relatively facile, inexpensive, and automatable preparation of peptides, coupled with low batch-to-batch variability, motivates the expanded use of assembling peptide hydrogels for biomedical applications. Integral to realizing dynamic peptide assemblies as functional biomaterials for tissue engineering is an understanding of the molecular and macroscopic features that govern assembly, morphology, and biological interactions. In this review, we first discuss the design of assembling peptides, including primary structure (sequence), secondary structure (e.g., α-helix and β-sheets), and molecular interactions that facilitate assembly into multiscale materials with desired properties. Next, we describe characterization tools for elucidating molecular structure and interactions, morphology, bulk properties, and biological functionality. Understanding of these characterization methods enables researchers to access a variety of approaches in this ever-expanding field. Finally, we discuss the biological properties and applications of peptide-based biomaterials for engineering several important tissues. By connecting molecular features and mechanisms of assembling peptides to the material and biological properties, we aim to guide the design and characterization of peptide-based biomaterials for tissue engineering and regenerative medicine. STATEMENT OF SIGNIFICANCE: Engineering peptide-based biomaterials that mimic the topological and mechanical properties of natural extracellular matrices provide excellent opportunities to direct cell behavior for regenerative medicine and tissue engineering. Here we review the molecular-scale features of assembling peptides that result in biomaterials that exhibit a variety of relevant extracellular matrix-mimetic properties and promote beneficial cell-biomaterial interactions. Aiming to inspire and guide researchers approaching this challenge from both the peptide biomaterial design and tissue engineering perspectives, we also present characterization tools for understanding the connection between peptide structure and properties and highlight the use of peptide-based biomaterials in neural, orthopedic, cardiac, muscular, and immune engineering applications.

Formation and physicochemical properties of glycogen phosphorylase in complex with a cationic polyelectrolyte

The accumulation of rabbit muscle glycogen phosphorylase b (RMGPb) in electrostatic complexes with the cationic polyelectrolyte poly 2-(dimethylamino) ethyl methacrylate in its quenched form (QPDMAEMA) was studied in two buffer solutions. In the N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid (BES) buffer, large complexes of RMGPb-QPDMAEMA were formed which adopted smaller sizes as QPDMAEMA concentration increased. However, in N-(2-hydroxyethyl)piperazine-N'-(2-ethanesulfonic acid) (HEPES) buffer, the hydrodynamic radius of the formed complexes gradually increased as the polymer concentration increased. Zeta potential measurements (ζ_p) showed that RMGPb significantly changed the ζ_p of the QPDMAEMA aggregates. Fluorescence studies showed that the interaction between RMGPb and QPDMAEAMA was enhanced as polymer concentration increased. Specifically, 8-anilinonaphthalene-1-sulfonic acid (ANS) fluorescence indicated that in the BES buffer the aggregates became denser as more QPDMAEMA was added, while in the HEPES buffer the density of the formed structures decreased. RMGPb's secondary structure was examined by Attenuated Total Reflection - Fourier Transform Infrared (ATR-FTIR) and Circular Dichroism (CD) showing that QPDMAEMA interaction with RMGPb does not induce any changes to the secondary structure of the enzyme. These observations suggest that cationic polyelectrolytes may be utilized for the formulation of RMGPb in multifunctional nanostructures and be further exploited in innovative biotechnology applications and bioinspired materials development.

Different Plant Sporopollenin Exine Capsules and Their Multifunctional Usage

Sporopollenin exine capsules (SECs) are highly resistant to heat and various acids and bases. They are also cheap, highly porous, eco-friendly polymer biomaterials with stable microencapsulation capacity. Due to their strong and uniquely shaped exine layers, they can allow growth on metal oxide materials, as a biotemplate for use in different applications. In this study, first, a single SEC extraction method was applied to three different pollens from Pinus, Fraxinus excelsior, and Tilia. Scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET) analysis, and thermogravimetric/differential thermal analysis (TGA/DTA) measurements both before and after the extraction process were performed to observe changes in surface area, morphology, porous structure, and degradation properties. The protein content and removal were analyzed by elemental and spectrophotometric analyses. Then, SECs were loaded by passive and centrifuge loading for drug delivery, and the loading capacities were analyzed by Fourier transform infrared spectroscopy and spectrophotometry. The method was successful in opening the pores and maintaining the structural integrity of SECs. It was determined that the morphology and porosity affected the encapsulation efficiency. According to the loading capacities, Tilia SECs were the most efficient SECs for both loading methods. In addition, three different SECs were hydrothermally coated with cobalt and then heat-treated to obtain a metal oxide structure. A CO₃O₄ supercapacitor electrode constructed using CO₃O₄-F. excelsior SEC powder had the best surface area parameters. The electrode showed a maximum specific capacity of 473 F/g for over 3000 continuous cycles of galvanostatic charge-discharge (GCD).

Bioconjugates of photon-upconversion nanoparticles for cancer biomarker detection and imaging

The detection of cancer biomarkers in histological samples and blood is of paramount importance for clinical diagnosis. Current methods are limited in terms of sensitivity, hindering early detection of disease. We have overcome the shortcomings of currently available staining and fluorescence labeling methods by taking an integrative approach to establish photon-upconversion nanoparticles (UCNP) as a powerful platform for cancer detection. These nanoparticles are readily synthesized in different sizes to yield efficient and tunable short-wavelength light emission under near-infrared excitation, which eliminates optical background interference of the specimen. Here we present a protocol for the synthesis of UCNPs by high-temperature co-precipitation or seed-mediated growth by thermal decomposition, surface modification by silica or poly(ethylene glycol) that renders the particles resistant to nonspecific binding, and the conjugation of streptavidin or antibodies for biological detection. To detect blood-based biomarkers, we present an upconversion-linked immunosorbent assay for the analog and digital detection of the cancer marker prostate-specific antigen. When applied to immunocytochemistry analysis, UCNPs enable the detection of the breast cancer marker human epidermal growth factor receptor 2 with a signal-to-background ratio 50-fold higher than conventional fluorescent labels. UCNP synthesis takes 4.5 d, the preparation of the antibody-silica-UCNP conjugate takes 3 d, the streptavidin-poly(ethylene glycol)-UCNP conjugate takes 2-3 weeks, upconversion-linked immunosorbent assay takes 2-4 d and immunocytochemistry takes 8-10 h. The procedures can be performed after standard laboratory training in nanomaterials research.

Amphiphilic Membrane Environments Regulate Enzymatic Behaviors of Salmonella Outer Membrane Protease

The role of an amphiphilic environment in the functional regulation of integral membrane proteins is well appreciated but how specific amphiphilic surrounding influences the conformational plasticity and function of a protein is less obvious. We focus on the Salmonella phosphoglycerate transport system (pgt)-encoded outer membrane protease E (PgtE), which plays an important role in tissue infiltration and survival of Salmonella enterica. Despite our understanding of its physiological functions, elucidation of its enzymatic behavior in response to the immediate amphiphilic surrounding is lacking. We monitor the proteolytic activity of PgtE reconstituted in Zwittergent 3-12 detergent micelles or a 1-palmitoyl-2-oleoyl-glycero-3-phosphocholine (POPC) bilayer and examine factors that influence its activity. We find, to our surprise, that PgtE, which is thought to elicit a rapid response toward various substrates, showed hysteretic enzymatic behavior, characterized by a prominent lag phase prior to achieving the exponential steady state in its detergent-stabilized form as well as in the outer membrane embedded native state in live bacteria. The lag phase was abolished under three conditions: preformation of an inactive detergent-stabilized PgtE-substrate complex without lipopolysaccharide (LPS), LPS-bound detergent-stabilized PgtE that had reached steady state velocity, or PgtE reconstituted into a POPC bilayer environment. Interestingly, detergent- and bilayer-stabilized PgtE showed comparable steady-state activity. And strikingly, lipopolysaccharide (LPS) becomes nonessential for the activation of PgtE when the protein is reconstituted in the phospholipid bilayer, contrasting a long-standing notion that LPS is required for proteases belonging to the omptin family to be proteolytically active. These findings suggest intriguing biological nuances for the proteolytic function of PgtE that were not well appreciated previously and offer new perspectives that may generally be applicable for omptins.

Introducing the multi-dimensional spectral phasors: a tool for the analysis of fluorescence excitation-emission matrices

The use of phasors to analyze fluorescence data was first introduced for time-resolved studies for a simpler mathematical analysis of the fluorescence-decay curves. Recently, this approach was extended to steady-state experiments with the introduction of the spectral phasors (SP), derived from the Fourier transform of the fluorescence emission spectrum. In this work, we revise key mathematical aspects that lead to an interpretation of SP as the characteristic function of a probability distribution. This formalism allows us to introduce a new tool, called multi-dimensional spectral phasor (MdSP) that seize, not only the information from the emission spectrum, but from the full excitation-emission matrix (EEM). In addition, we developed a homemade open-source Java software to facilitate the MdSP data processing. Due to this mathematical conceptualization, we settled a mechanism for the use of MdSP as a tool to tackle spectral signal unmixing problems in a more accurate way than SP. As a proof of principle, with the use of MdSP we approach two important biophysical questions: protein conformational changes and protein-ligand interactions. Specifically, we experimentally measure the EEM changes upon denaturation of human serum albumin (HSA) or during its association with the fluorescence dye 1,8-anilinonaphtalene sulphate (ANS) detected via tryptophan-ANS Förster Resonance Energy Transfer (FRET). In this sense, MdSP allows us to obtain information of the system in a simpler and finer way than the traditional SP. Specifically, understanding a protein's EEM as a molecular fingerprint opens new doors for the use of MdSP as a tool to analyze and comprehend protein conformational changes and interactions.

Benzothiazole Pyrazoline: Acid-Switchable Absorption and Fluorescence of Photoinduced Electron Transfer (PET)

Acid-responsive fluorescent compounds were prepared by introducing an ortho-hydroxyphenyl to pyrazoline with a benzothiazole backbone. These compounds demonstrated normal fluorescence photoinduced electron transfer (PET) under neutral conditions but the addition of trifluoroacetic acid showed an arctic blue fluorescence, we verified that a protonation process of nitrogen in the thiazole ring which weakened the ability of thiazole to donate electrons to the pyrazoline and changed the photoinduced electron transfer led to photoinduced electron transfer (PET), which was the mechanism of the fluorescence quenching phenomenon under strongly acidic conditions. The photophysical properties of Benzothiazole pyrazoline exhibited blue emission at 421 nm in aqueous DMSO. The blue shift in the emission was switched by acid in DMSO, showing the compound's distinct fluorescence peak at 554 nm. To investigate solvatochromism, eight different solvents were used. The red-shift emission observed in enhancing the polarity of solvents and emission in DMSO suggested the conformation of the molecule which led to the intramolecular charge transfer by color and emission changes. Furthermore, the probe was also applied using the High-performance liquid chromatography (HPLC) with a UV detector to determine the trifluoroacetic acid in water samples. Interestingly, the method was found to be linear over the range of 10.0 µg L^-1 to 250.0 µg L^-1 (0.999). Under the optimum condition, the separation of trifluoroacetic acid was achieved in 20 min with the LOD of 1.3 µg L^-1 and LOQ of 5.1 µg L^-1. This proposed method also showed satisfactory results when applied for the analysis of trifluoroacetic acid in a water sample.

Physicochemical Characterization of In Vitro LDL Glycation and Its Inhibition by Ellagic Acid (EA): An In Vivo Approach to Inhibit Diabetes in Experimental Animals

Hundreds of millions of people around the globe are afflicted by diabetes mellitus. The alteration in glucose fixation process might result into hyperglycaemia and could affect the circulating plasma proteins to undergo nonenzymatic glycation reaction. If it is unchecked, it may lead to diabetes with increase in advanced glycation end products (AGEs). Therefore, the present study was designed to inhibit the diabetes and glycation by using natural antioxidant “ellagic acid” (EA). In this study, we explored the antidiabetes and antiglycation potential of EA in both in vitro (EA at micromolar concentration) and in vivo systems. The EA concentrations of 10 and 20 mg kg⁻¹B.W./day were administered orally for 25 days to alloxan-induced diabetic rats, a week after confirmation of stable diabetes in animals. Intriguingly, EA supplementation in diabetic rats reversed the increase in fasting blood sugar (FBS) and hemoglobin A1c (HbA1c) level. EA also showed an inhibitory role against glycation intermediates including dicarbonyls, as well as AGEs, investigated in a glycation mixture with in vitro and in vivo animal plasma samples. Additionally, EA treatment resulted in inhibition of lipid peroxidation-mediated malondialdehyde (MDA) and conjugated dienes (CD). Furthermore, EA exhibited an antioxidant property, increased the level of plasma glutathione (GSH), and also helped to decrease histological changes evaluated by histoimmunostaining of animal kidney tissues. The results from our investigation clearly indicates the antiglycative property of EA, suggesting EA as an adequate inhibitor of glycation and diabetes, which can be investigated further in preclinical settings for the treatment and management of diabetes-associated complications.

Modern Sensor Tools and Techniques for Monitoring, Controlling, and Improving Cell Culture Processes

The growing biopharmaceutical industry has reached a level of maturity that allows for the monitoring of numerous key variables for both process characterization and outcome predictions. Sensors were historically used in order to maintain an optimal environment within the reactor to optimize process performance. However, technological innovation has pushed towards on-line in situ continuous monitoring of quality attributes that could previously only be estimated off-line. These new sensing technologies when coupled with software models have shown promise for unique fingerprinting, smart process control, outcome improvement, and prediction. All this can be done without requiring invasive sampling or intervention on the system. In this paper, the state-of-the-art sensing technologies and their applications in the context of cell culture monitoring are reviewed with emphasis on the coming push towards industry 4.0 and smart manufacturing within the biopharmaceutical sector. Additionally, perspectives as to how this can be leveraged to improve both understanding and outcomes of cell culture processes are discussed.

A unique aromatic cluster near the active site of H. pylori CPA is essential for catalytic function

Polyamines are essential for cell growth and proliferation. In plants and many bacteria, including Helicobacter pylori, the parent polyamine putrescine is only produced through the metabolism of N-carbamoylputrescine by N-carbamoylputrescine amidase (CPA). Thus, CPA is a crucial intermediate enzyme. Moreover, the absence of CPA in humans makes its presence in H. pylori a potential target for the development of new therapeutics against this pathogen. Despite this enzyme's presence in plants and bacteria, its function is not completely explored. Using structure-guided biochemical and biophysical studies on H. pylori CPA, we discovered an aromatic cluster containing four conserved tryptophans near the catalytic site and elucidated its role. Mutational studies revealed that they are individually vital to enzyme function. Unlike wild-type, which forms a hexamer, the Trp to Ala mutants only formed dimers. Interestingly, two other conserved residues, Gln155 and Asp278, interact with the tryptophan cluster and perform similar roles. Our results indicate that aromatic-aromatic and H-bonding contacts between the residues (Trp156-Trp273, Trp196-Gln155, and Trp153-Asp278) play a crucial role in stimulating activity through hexamer formation. Additionally, Trp156 is essential to generating a catalytically efficient hexamer. These results suggest dual roles for the tryptophans; in hexamer formation and in generating its functionally active form, thereby providing a mechanistic understanding into the role of the cluster. We also elucidated the catalytic roles of Glu43, Lys115, and Cys152, which are present at the active site. Our findings highlight, for the first time, the importance of a tryptophan cluster in H. pylori CPA that can be exploited to design therapeutic inhibitors.

Anti-α-Glucosidase and Antiglycation Activities of α-Mangostin and New Xanthenone Derivatives: Enzymatic Kinetics and Mechanistic Insights through In Vitro Studies

Diabetes mellitus is characterized by chronic hyperglycemia that promotes ROS formation, causing severe oxidative stress. Furthermore, prolonged hyperglycemia leads to glycation reactions with formation of AGEs that contribute to a chronic inflammatory state. This research aims to evaluate the inhibitory activity of α-mangostin and four synthetic xanthenone derivatives against glycation and oxidative processes and on α-glucosidase, an intestinal hydrolase that catalyzes the cleavage of oligosaccharides into glucose molecules, promoting the postprandial glycemic peak. Antiglycation activity was evaluated using the BSA assay, while antioxidant capacity was detected with the ORAC assay. The inhibition of α-glucosidase activity was studied with multispectroscopic methods along with inhibitory kinetic analysis. α-Mangostin and synthetic compounds at 25 µM reduced the production of AGEs, whereas the α-glucosidase activity was inhibited only by the natural compound. α-Mangostin decreased enzymatic activity in a concentration-dependent manner in the micromolar range by a reversible mixed-type antagonism. Circular dichroism revealed a rearrangement of the secondary structure of α-glucosidase with an increase in the contents of α-helix and random coils and a decrease in β-sheet and β-turn components. The data highlighted the anti-α-glucosidase activity of α-mangostin together with its protective effects on protein glycation and oxidation damage.

Extension of human GCSF serum half-life by the fusion of albumin binding domain

Granulocyte colony stimulating factor (GCSF) can decrease mortality of patients undergo chemotherapy through increasing neutrophil counts. Many strategies have been developed to improve its blood circulating time. Albumin binding domain (ABD) was genetically fused to N-terminal end of GCSF encoding sequence and expressed as cytoplasmic inclusion bodies within Escherichia coli. Biological activity of ABD-GCSF protein was assessed by proliferation assay on NFS-60 cells. Physicochemical properties were analyzed through size exclusion chromatography, circular dichroism, intrinsic fluorescence spectroscopy and dynamic light scattering. Pharmacodynamics and pharmacokinetic properties were also investigated in a neutropenic rat model. CD and IFS spectra revealed that ABD fusion to GCSF did not significantly affect the secondary and tertiary structures of the molecule. DLS and SEC results indicated the absence of aggregation formation. EC50 value of the ABD-GCSF in proliferation of NFS-60 cells was 75.76 pg/ml after 72 h in comparison with control GCSF molecules (Filgrastim: 73.1 pg/ml and PEG-Filgrastim: 44.6 pg/ml). Animal studies of ABD-GCSF represented improved serum half-life (9.3 ± 0.7 h) and consequently reduced renal clearance (16.1 ± 1.4 ml/h.kg) in comparison with Filgrastim (1.7 ± 0.1 h). Enhanced neutrophils count following administration of ABD-GCSF was comparable with Filgrastim and weaker than PEG-Filgrastim treated rats. In vitro and in vivo results suggested the ABD fusion as a potential approach for improving GCSF properties.

Naphthalene-functionalized resorcinarene as selective, fluorescent self-quenching sensor for kynurenic acid

Naphthalene-functionalized resorcinarene selectively binds kynurenic acid in the presence of excess tryptophan in aqueous media, highlighting the potential of functionalized resorcinarenes as sensory recognition elements for biomolecular analytes.

Smartphone-based autofluorescence imaging to detect bacterial species on laboratory surfaces

This work demonstrated instantaneous, reagent- and staining-free, smartphone-based autofluorescence detection of bacterial contamination on typical laboratory desk surfaces. Detection was successfully distinguished from protein, salt, and tap water.

Nano Differential Scanning Fluorimetry-Based Thermal Stability Screening and Optimal Buffer Selection for Immunoglobulin G

Nano differential scanning fluorimetry (nanoDSF) is a high-throughput protein stability screening technique that simultaneously monitors protein unfolding and aggregation properties. The thermal stability of immunoglobulin G (IgG) was investigated in three different buffers (sodium acetate, sodium citrate, and sodium phosphate) ranging from pH 4 to 8. In all three buffers, the midpoint temperature of thermal unfolding (T_m) showed a tendency to increase as the pH increased, but the aggregation propensity was different depending on the buffer species. The best stability against aggregation was obtained in the sodium acetate buffers below pH 4.6. On the other hand, IgG in the sodium citrate buffer had higher aggregation and viscosity than in the sodium acetate buffer at the same pH. Difference of aggregation between acetate and citrate buffers at the same pH could be explained by a protein-protein interaction study, performed with dynamic light scattering, which suggested that intermolecular interaction is attractive in citrate buffer but repulsive in acetate buffer. In conclusion, this study indicates that the sodium acetate buffer at pH 4.6 is suitable for IgG formulation, and the nanoDSF method is a powerful tool for thermal stability screening and optimal buffer selection in antibody formulations.

Negishi Cross-Coupling Provides Alkylated Tryptophans and Tryptophan Regioisomers

Mild transition‐metal catalysed cross‐couplings enable direct functionalisation of biocatalytically halogenated tryptophans with alkyl iodides, representing a new alternative for late‐stage derivatisations of halogenated aromatic amino acids. Moreover, this strategy enables preparation of (homo)tryptophan regioisomers in a simple two‐step synthesis using a Pd‐catalysed Negishi cross coupling. This method provides access to non‐canonical constitutional surrogates of tryptophan, ready for use in peptide synthesis.

Myopathy-associated G154S mutation causes important changes in the conformational stability, amyloidogenic properties, and chaperone-like activity of human αB-crystallin

Glycine to serine substitution at position 154 of human αB-crystallin (αB-Cry) is behind the development of cardiomyopathy and late-onset distal myopathy. The current study was conducted with the aim to investigate the structural and functional features of the G154S mutant αB-Cry using various spectroscopic techniques and microscopic analyses. The secondary and tertiary structures of human αB-Cry were preserved mainly in the presence of G154S mutation, but the mutant protein indicated a reduced chaperone-like activity when γ-Cry as its natural partner in eye lenses was the substrate protein. Moreover, a significant reduction in the enzyme refolding ability and in vivo chaperone activity of the mutant protein were observed. Also, the mutant protein displayed reduced conformational stability upon urea-induced denaturation. Both fluorescence and electron microscopic analyses suggested that G154S mutant protein has an increased susceptibility for amyloid fibril formation. Therefore, the pathomechanism of G154S mutation can be explained by its attenuated chaperone function, decreased conformational stability, and increased amyloidogenic propensity. Some of these important changes may also alter the correct interaction of the mutated αB-Cry with its target proteins in myopathy.

Rapid, high throughput protein estimation method for saponin and alhydrogel adjuvanted R21 VLP Malaria vaccine based on intrinsic fluorescence

Protein content estimation of recombinant vaccines at drug product (DP) stage is a crucial lot release and stability indicating assay in biopharmaceutical industries. Regulatory bodies such as US-FDA and WHO necessitates the quantitation of protein content to assess process parameters as well as formulation losses. Estimation of protein content at DP stage in presence of adjuvants (e.g AlOOH, AlPO₄, saponin and squalene) is quite challenging, and the challenge intensifies when the target protein is in Virus like particles (VLP) form, owing to its size and structural complexity. Methods available for protein estimation of adjuvanted vaccines mostly suffer from inaccuracy at lower protein concentrations and in most cases require antigen desorption before analysis. Present research work is based on the development of a rapid plate-based method for protein estimation through intrinsic fluorescence by using Malaria vaccine R21 VLP as a model protein. Present method exhibited linearity for protein estimation of R21, in the range of 5-30 µg/mL in Alhydrogel and 4-20 µg/mL for Matrix M adjuvant. The method was validated as per ICH guidelines. The limit of quantification was found to be 0.94 µg/mL for both Alhydrogel and Matrix M adjuvanted R21. The method was found specific, precise and repeatable. This method is superior in terms of less sample quantity requirement, multiple sample analysis, short turnaround time and is non-invasive. This method was found to be stability indicating, works for other proteins containing tryptophan residues and operates well even in presence of host cell proteins. Based on the study, present method can be used in vaccine industries for routine in-process sample analysis (both inline and offline), lot release of VLP based drug products in presence of Alhydrogel and saponin based adjuvant systems.

Supramolecular organization of Cytochrome-C into quantum-dot decorated macromolecular network under pH and thermal stress

The holo form of Cytochrome-C which is involved in the electron transfer chain of aerobic and anaerobic respiration remains structurally intact by its complex with heme. However, when a prolonged thermal and pH stress was applied, heme was found to abruptly dissociate from the holo protein, resulting in complete collapse of the three-dimensional functional structure. Interestingly, two distinct structures were formed as the consequence of the dissociation event: (i) A macromolecular amyloid-network formed by the collapsed protein fragments, generated by self-oxidation, and (ii) Fe-containing Quantum-Dots (FeQDs) with 2-3 nm diameter formed by heme reorganization. Further adding to intrigue, the FeQDs were re-adsorbed on the surface of the amyloid network leading to FeQD-decorated macromolecular amyloid matrix. The heme-interactant Met80, constituting the amyloidogenic region, initiates the amylogenic cascade, and gradual exposure of Trp59 synergistically emit intrinsic fluorescence alongside FeQDs. The development of the aforementioned events were probed through a multitude of biophysical, chemical and computational analyses like ThT/ANS/intrinsic fluorescence assays, CD-spectroscopy, FETEM/STEM/elemental mapping, Foldamyloid/Foldunfold/Isunstruct/H-protection/LIGplot analyses, etc. The FeQD-decorated amyloid-network was found to exhibit gel-like property, which supported the growth of BHK-21 fibroblast without cytotoxicity. Further studies on FeQD-decorated Cytochrome C amyloid network might open possibilities to design advanced biomaterial for diverse biological applications.

Expanding the Scope of Polyoxometalates as Artificial Proteases towards Hydrolysis of Insoluble Proteins

Despite the enormous importance of insoluble proteins in biological processes, their structural investigation remains a challenging task. The development of artificial enzyme-like catalysts would greatly facilitate the elucidation of their structure since currently used enzymes in proteomics largely lose activity in the presence of surfactants, which are necessary to solubilize insoluble proteins. In this study, the hydrolysis of a fully insoluble protein by polyoxometalate complexes as artificial proteases in surfactant solutions is reported for the first time. The hydrolysis of zein as a model protein was investigated in the presence of Zr(IV) and Hf(IV) substituted Keggin-type polyoxometalates (POMs), (Et₂ NH₂ )₁₀ [M(α-PW₁₁ O₃₉ )₂ ] (M = Zr or Hf), and different concentrations of the anionic surfactant sodium dodecyl sulfate (SDS). Selective hydrolysis of the protein upon incubation with the catalyst was observed, and the results indicate that the hydrolytic selectivity and activity of the POM catalysts strongly depends on the concentration of surfactant. The molecular interactions between the POM catalyst and zein in the presence of SDS were explored using a combination of spectroscopic techniques which indicated competitive binding between POM and SDS towards the protein. Furthermore, the formation of micellar superstructures in ternary POM/surfactant/protein solutions has been confirmed by conductivity and Dynamic Light Scattering measurements.

Different molecular sizes and chain conformations of water-soluble yeast β-glucan fractions and their interactions with receptor Dectin-1

Although β-glucan could bind to Dectin-1 to exert bioactivity, the influence of molecular size and chain conformation of β-glucan on its interaction with Dectin-1 is still unclear. This work investigated the molecular sizes and chain conformations of five water-soluble yeast β-glucan (WYG1-5) fractions as well as their interactions with Dectin-1 by fluorescence spectroscopy and microscale thermophoresis. Results revealed a spherical conformation for higher molecular weight WYG and a stiff chain conformation for smaller molecular weight WYG. The WYG and Dectin-1 interactions were in the order of WYG-2 > WYG-1 > WYG-3 > WYG-4 > WYG-5. The spherical WYG-2 exhibited the largest binding constant of 7.91 × 10⁵ M¹ and the lowest dissociation constant of 22.1 nM to Dectin-1. Additionally, the underlying interaction mechanism showed that it may be easier for spherical WYG with longer side chains to interact with receptor Dectin-1.

β-Cell Pathophysiology: A Review of Advanced Optical Microscopy Applications

β-cells convert glucose (input) resulting in the controlled release of insulin (output), which in turn has the role to maintain glucose homeostasis. β-cell function is regulated by a complex interplay between the metabolic processing of the input, its transformation into second-messenger signals, and final mobilization of insulin-containing granules towards secretion of the output. Failure at any level in this process marks β-cell dysfunction in diabetes, thus making β-cells obvious potential targets for therapeutic purposes. Addressing quantitatively β-cell (dys)function at the molecular level in living samples requires probing simultaneously the spatial and temporal dimensions at the proper resolution. To this aim, an increasing amount of research efforts are exploiting the potentiality of biophysical techniques. In particular, using excitation light in the visible/infrared range, a number of optical-microscopy-based approaches have been tailored to the study of β-cell-(dys)function at the molecular level, either in label-free mode (i.e., exploiting intrinsic autofluorescence of cells) or by the use of organic/genetically-encoded fluorescent probes. Here, relevant examples from the literature are reviewed and discussed. Based on this, new potential lines of development in the field are drawn.

Protection of human γD-crystallin protein from ultraviolet C-induced aggregation by ortho-vanillin

Cataract is known as one of the leading causes of vision impairment worldwide. While the detailed mechanism of cataratogenesis remains unclear, cataract is believed to be correlated with the aggregation and/or misfolding of human ocular lens proteins called crystallins. A 173-residue structural protein human γD-crystallin is a major γ-crystallin protein in the human eye lens and associated with the development of juvenile and mature-onset cataracts. This work is aimed at investigating the effect of a small molecule, e.g., ortho-vanillin, on human γD-crystallin aggregation upon exposure to ultraviolet-C irradiation. According to the findings of right-angle light scattering, transmission electron microscopy, and gel electrophoresis, ortho-vanillin was demonstrated to dose-dependently suppress ultraviolet-C-triggered aggregation of human γD-crystallin. Results from the synchronous fluorescence spectroscopy, tryptophan fluorescence quenching, and molecular docking studies revealed the structural change of γD-crystallin induced by the interaction/binding between ortho-vanillin and protein. We believe the outcome from this work may contribute to the development of potential therapeutics for cataract.

Expression and one-step purification of active lipoprotein lipase contemplated by biophysical considerations

Lipoprotein lipase (LPL) is essential for intravascular lipid metabolism and is of high medical relevance. Since LPL is notoriously unstable, there is an unmet need for a robust expression system producing high quantities of active and pure recombinant human LPL. We showed previously that bovine LPL purified from milk is unstable at body temperature (T_m is 34.8 °C), but in the presence of the endothelial transporter glycosylphosphatidylinositol-anchored high-density lipoprotein-binding protein 1 (GPIHBP1) LPL is stabile (T_m increases to 57.6 °C). Building on this information, we now designed an expression system for human LPL using Drosophila S2 cells grown in suspension at high cell density and at an advantageous temperature of 25 °C. We co-transfected S2 cells with human LPL, LMF1 and soluble GPIHBP1 to provide an efficient chaperoning and stabilization of LPL in all compartments during synthesis and after secretion into the conditioned medium. For LPL purification, we used heparin-Sepharose affinity chromatography, which disrupted LPL-GPIHBP1 complexes causing GPIHBP1 to elute with the flow-through of the conditioned media. This one-step purification procedure yielded high quantities of pure and active LPL (4‒28 mg/L). Purification of several human LPL variants (furin-cleavage resistant mutant R297A, active-site mutant S132A, and lipid-binding-deficient mutant W390A-W393A-W394A) as well as murine LPL underscores the versatility and robustness of this protocol. Notably, we were able to produce and purify LPL containing the cognate furin-cleavage site. This method provides an efficient and cost-effective approach to produce large quantities of LPL for biophysical and large-scale drug discovery studies.

New Physical Hydrogels Based on Co-Assembling of FMOC-Amino Acids

In the last years, physical hydrogels have been widely studied due to the characteristics of these structures, respectively the non-covalent interactions and the absence of other necessary components for the cross-linking processes. Low molecular weight gelators are a class of small molecules which form higher ordered structures through hydrogen bonding and π-π interactions. In this context it is known that the formation of hydrogels based on FMOC-amino acids is determined by the primary structures of amino acids and the secondary structure arrangement (alpha-helix or beta-sheet motifs). The present study aimed to obtain supramolecular gels through co-assembly phenomenon using FMOC-amino acids as low molecular weight gelators. The stability of the new structures was evaluated by the vial inversion test, while FTIR spectra put into evidence the interaction between the compounds. The gel-like structure is evidenced by viscoelastic parameters in oscillatory shear conditions. SEM microscopy was used to obtain the visual insight into the morphology of the physical hydrogel network while DLS measurements highlighted the sol-gel transition. The molecular arrangement of gels was determined by circular dichroism, fluorescence and UV-Vis spectroscopy.

Bimolecular quenching of tryptophan fluorescence in a membrane protein: Evolution of local solvation and environment during folding into a bilayer

Fluorescence spectroscopy, including Stern-Volmer quenching, is a valuable tool for the study of protein dynamics. Changes in protein solvation during the folding reaction of a membrane protein, Outer membrane protein A (OmpA), into lipid bilayers was probed with bimolecular fluorescence quenching with acrylamide quencher. Six single-tryptophan OmpA mutants (W7, W15, W57, W102, W129, and W143) allowed for site-specific investigations at varying locations within the transmembrane β-barrel domain. A sphere-of-action quenching model that combines both static and dynamic components gave rise to Stern-Volmer quenching constants, KD, for OmpA denatured in 8.0 M urea, aggregated in 0.5 M urea, adsorbed onto small unilamellar vesicles (SUVs), and folded in SUVs (t = 6 hrs). The average KD values were KDdenatured(6.4M-1)>KDaggregated5.9M-1>KDadsorbed(1.9M-1)>KDfolded(0.6M-1). With knowledge of the fluorescence lifetimes in the absence of quencher, the bimolecular quenching constants, kq, were derived; the evolution of kq (and therefore KD)during the folding reaction into SUVs (t = 0 hr to t = 6 hrs) revealed desolvation timescales, τdesolv of 41-46 min (W7, W15, W57, W102), 27 min (W129), and 15 min (W143). The evolution of λmax during folding revealed fast and slow components, τenvironmentfast and τenvironmentslow of 7-13 min and 25-84 min, respectively, for all mutants. For the five lipid- facing mutants (W7, W15, W57, W129, and W143), the general trend was τenvironmentfast7-13min<τdesolv15-46min≤τenvironmentslow(25-84min). These results suggest that there is an initial fast step in which there is a large change in polarity to a hydrophobic environment, followed by a slower desolvation process during evolution within the hydrophobic environment. These results complement previous mechanisms of concerted folding and provide insights into site-specific changes in solvation during formation of native β-barrel structure.

A Comparative Analysis of Punicalagin Interaction with PDIA1 and PDIA3 by Biochemical and Computational Approaches

In a previous work, it was shown that punicalagin, an active ingredient of pomegranate, is able to bind to PDIA3 and inhibit its disulfide reductase activity. Here we provide evidence that punicalagin can also bind to PDIA1, the main expressed form of protein disulfide isomerase (PDI). In this comparative study, the affinity and the effect of punicalagin binding on each protein were evaluated, and a computational approach was used to identify putative binding sites. Punicalagin binds to either PDIA1 or PDIA3 with a similar affinity, but the inhibition efficacy on protein reductase activity is higher for PDIA3. Additionally, punicalagin differently affects the thermal denaturation profile of both proteins. Molecular docking and molecular dynamics simulations led to propose a punicalagin binding mode on PDIA1 and PDIA3, identifying the binding sites at the redox domains a’ in two different pockets, suggesting different effects of punicalagin on proteins’ structure. This study provides insights to develop punicalagin-based ligands, to set up a rational design for PDIA3 selective inhibitors, and to dissect the molecular determinant to modulate the protein activity.

Water-Soluble Dioxidovanadium(V) Complexes of Aroylhydrazones: DNA/BSA Interactions, Hydrophobicity, and Cell-Selective Anticancer Potential

Five new anionic aqueous dioxidovanadium(V) complexes, [{VO₂L^1,2}A(H₂O)_n]_α (1-5), with the aroylhydrazone ligands pyridine-4-carboxylic acid (3-ethoxy-2-hydroxybenzylidene)hydrazide (H₂L¹) and furan-2-carboxylic acid (3-ethoxy-2-hydroxybenzylidene)hydrazide (H₂L²) incorporating different alkali metals (A = Na⁺, K⁺, Cs⁺) as countercation were synthesized and characterized by various physicochemical techniques. The solution-phase stabilities of 1-5 were determined by time-dependent NMR and UV-vis, and also the octanol/water partition coefficients were obtained by spectroscopic techniques. X-ray crystallography of 2-4 confirmed the presence of vanadium(V) centers coordinated by two cis-oxido-O atoms and the O, N, and O atoms of a dianionic tridentate ligand. To evaluate the biological behavior, all complexes were screened for their DNA/protein binding propensity through spectroscopic experiments. Finally, a cytotoxicity study of 1-5 was performed against colon (HT-29), breast (MCF-7), and cervical (HeLa) cancer cell lines and a noncancerous NIH-3T3 cell line. The cytotoxicity was cell-selective, being more active against HT-29 than against other cells. In addition, the role of hydrophobicity in the cytotoxicity was explained in that an optimal hydrophobicity is essential for high cytotoxicity. Moreover, the results of wound-healing assays indicated antimigration in case of HT-29 cells. Remarkably, 1 with an IC₅₀ value of 5.42 ± 0.15 μM showed greater activity in comparison to cisplatin against the HT-29 cell line.

Thymoquinone provides structural protection of human hemoglobin against oxidative damage: Biochemical studies

Hydroxyl radicals (OH^.) are one of the most active reactive oxidants recognized for their deleterious effects to cause protein oxidative damage. Thymoquinone, a monoterpene molecule abundantly present in black cumin and known for its pharmacological activities, but its activity against the OH^.-induced protein oxidative damage has never been explored. This study determined the therapeutic potential of thymoquinone against OH^.-induced oxidative human hemoglobin damage. Novel data demonstrated that thymoquinone provides structural protection of hemoglobin against oxidative damage. Treatment of hemoglobin with OH^. induces hypochromicity at 280 and 405 nm, whereas thymoquinone reversed these hypochromic effects. In addition, OH^. cause significant reduction in tryptophan fluorescence, however thymoquinone also reversed these damaging effects. Thymoquinone also reduces OH^.-induced hydrophobicity and also reduces OH^.-induced carbonylation. Moreover, it also inhibits thermal stabilization of OH^.-hemoglobin complex. SDS-PAGE of unmodified hemoglobin showed four bands, which disappeared upon OH^. treatment and these changes were also retained by thymoquinone. In conclusion, this is the first study that shows the therapeutic potential of thymoquinone against OH^.-induced oxidative damage in human hemoglobin.

In silico and multi-spectroscopic analyses on the interaction of 5-amino-8-hydroxyquinoline and bovine serum albumin as a potential anticancer agent

5-Amino-8-hydroxyquinoline (5A8HQ), an amino derivative of 8-hydroxyquinoline, has become a potential anticancer candidate because of its promising proteasome inhibitory activity to overcome and yet synergize bortezomib for fighting cancers. Therefore, in this study, its physicochemical properties and interaction activities with serum protein have extensively been elucidated by both in vitro and in silico approaches to fulfill the pharmacokinetic and pharmacodynamic gaps. 5A8HQ exhibited the drug-likeness properties, where oral administration seems to be a route of choice owing to its high-water solubility and intestinal absorptivity. Multi-spectroscopic investigations suggested that 5A8HQ tended to associate with bovine serum albumin (BSA), a representative of serum protein, via the ground-state complexation. It apparently bound in a protein cleft between subdomains IIA and IIIA of BSA as suggested by the molecular docking and molecular dynamics simulations. The binding was mainly driven by hydrogen bonding and electrostatic interactions with a moderate binding constant at 10⁴ M⁻¹, conforming with the predicted free fraction in serum at 0.484. Therefore, 5A8HQ seems to display a good bioavailability in plasma to reach target sites and exerts its potent pharmacological activity. Likewise, serum albumin is a good candidate to be reservoir and transporter of 5A8HQ in the circulatory system.

A1 and A2 milk caseins-comparative FTIR and spectroflourimetry analysis

Around 35% of the total caseins are β-caseins, which are further classified as A1 β-caseins and A2 β-caseins, based on differences in the amino acid composition of both. A2 is the wild type genetic variant of β-casein while A1 is the mutant. The present study aimed at the isolation of A1 and A2 casein from different cow milk sources and its characterization by using simple chemical techniques, viz. FTIR and spectrofluorimetry. The commercial milk sample from Bos indicus (Gir) (A2) was obtained from Bombay Panjrapole, Mumbai and two commercially available packaged cow milk samples (pasteurized, skimmed) namely from Gokul and Mother Dairy (A1) were also obtained for comparison analysis from the local market. The isolation of casein was performed by standard method and analyzed using SDS-PAGE, FTIR and spectrofluorimetry. There was evidence that the A2 milk lacked histidine and rich in aromatic amino acids like tryptophan using FTIR and spectrofluorimetry techniques.

Development of purification process for dual-function recombinant human heavy-chain ferritin by the investigation of genetic modification impact on conformation

Ferritin is a promising drug delivery platform and has been functionalized through genetic modifications. This work has designed and expressed a dual-functional engineered human heavy-chain ferritin (HFn) with the inserted functional peptide PAS and RGDK to extend half-life and improve tumor targeted drug delivery. A facile and cost-effective two-step purification pathway for recombinant HFn was developed. The genetic modification was found to affect HFn conformation, and therefore varied the purification performance. Heat-acid precipitation followed by butyl fast flow hydrophobic interaction chromatography (HIC) has been developed to purify HFn and modified HFns. Nucleic acid removal reached above 99.8% for HFn and modified HFns. However, HFn purity reached above 95% and recovery yield (overall) above 90%, compared with modified HFns purity above 82% and recovery yield (overall) above 58%. It is interesting to find that the inserted functional peptides significantly changed the molecule conformation, where a putative turnover of the E-helix with the inserted functional peptides formed a "flop" conformation, in contrast with the "flip" conformation of HFn. It could be the cause of fragile stability of modified HFns, and therefore less tolerant to heat and acid condition, observed by the lower recovery yield in heat-acid precipitation.