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•Proteins can be modified by sonochemical and by sonomechanical means.•Ultrasound enhanced transport effects are unique ways to change the 3D folded structure of proteins.•Ultrasound ...effects enhances enzymatic reactions.
The review focus on the effect of ultrasound on protein functionality. The presence of transient ultrasonic mechanical waves induce various sonochemical and sonomechanical effects on a protein. Sonochemical effects include the breakage of chains and/or the modification of side groups of aminoacids. Sonomechanical modifications by enhanced molecular agitation, might lead to the transient or permanent modification of the 3D structure of the folded protein. Since the biological function of proteins depends on the maintenance of its 3D folded structure, both sonochemical and sonomechanical effects might affect its properties. A protein might maintain its 3D structure and functionality after minor sonochemical effects, however, the enhanced mass transfer by sonomechanical effects might expose internal hydrophobic residues of the protein, making protein unfolding to an irreversible denatured state. Ultrasound enhanced mass transport effects are unique pathways to change the 3D folded structure of proteins which lead to a new functionality of proteins as support shield materials during the formation microspheres. Enzymes are proteins and their reactions should be conducted in a reactor set-up where enzymes are protected from sonic waves to maximize their catalytic efficiency. In this review, focused examples on protein dispersions/emulsions and enzyme catalysis are given.
The demand for adequate and ecologically acceptable procedures to produce the most differentiated products has been growing in recent decades, with enzymes being excellent examples of the advances ...achieved so far. Lipases are astonishing catalysts with a vast range of applications including the synthesis of esters, flavors, biodiesel, and polymers. The broad specificity of the substrates, as well as the regio‐, stereo‐, and enantioselectivity, are the differentiating factors of these enzymes. Structural modification is a current approach to enhance the activity of lipases. Chemical modification of lipases to improve catalytic performance is of great interest considering the increasingly broad fields of application. Together with the physical immobilization onto solid supports, different strategies have been developed to produce catalysts with higher activity and stability. In this review, practical insights into the different strategies developed in recent years regarding the modification of lipases are described. For the first time, the impact of the modifications on the activity and stability of lipases, as well as on the biotechnological applications, is fully compiled.
Graphical and Lay Summary
The most recent methodologies for chemical modification of lipases are covered in this review. Their prospective uses, as well as the impact of chemical changes on the activity and stability of lipases, are thoroughly detailed.
Lipase from Thermomyces lanuginosus is one of the most explored enzymes for the esterification of several added‐value industrial compounds, such as biodiesel, fragrances, and flavors. Its selectivity ...in these reactions is mostly related with its activity towards small alcohols. In this work, the impact of the chemical modification, with 4 dodecyl chains at its surface, was evaluated regarding its transesterification and esterification activities, comparing with the native form. Linear size‐differentiated alcohols (from 1 to 20 carbons in the aliphatic chain) were used to explore for the first time the effect of the chain length in both transesterification and esterification reactions, using p‐nitrophenyl palmitate and oleic acid as model compounds, respectively. The chemically modified lipase showed an outstanding improvement of its catalytic performance than the native enzyme, being this increase directly proportional to the size of the alcohols chain used as substrates. The enormous potential and remarkable versatility of this novel super catalyst was here demonstrated, where diverse types of esters, differing in their potential applications (biodiesel, cosmetics, fine chemistry), were efficiently synthesized. The produced esters were fully characterized by 1H NMR, GC‐MS, and FTIR.
The chemical modification of lipase from Thermomyces lanuginosus using dodecyl aldehyde as linker, showed to beneficially improve its catalytic activity. The results reported in this paper, showed an outstanding increase of its activity towards esterification and transesterification reactions, comparing with the native form, being the most pronounced improvement obtained when using the longest alcohol chains for both type of reactions.
Aiming to reduce the toxicity and operational costs often associated to chemical processes, the enzymatic synthesis is applied herein as a sustainable route for producing polyesters. The use of ...NADES’ (Natural Deep Eutectic Solvents) components as a source of monomers for the synthesis of polymers through lipase‐catalyzed esterification in an anhydrous medium is detailed for the first time. Three NADES composed by glycerol and an organic base, or acid, were used to produce polyesters, through polymerization reactions catalyzed by Aspergillus oryzae lipase. High polyester conversion rates (above 70 %), containing at least 20 monomeric units (glycerol:organic acid/base (1 : 1)), were observed by matrix‐assisted laser desorption/ionization‐time‐of‐flight (MALDI‐TOF) analysis. The NADES monomers′ capacity for polymerization, along with their non‐toxicity, cheap cost, and simplicity of production, sets up these solvents as a greener and cleaner approach for the synthesis of high value‐added products.
Monomers of natural deep eutectic solvents (NADES) were applied as substrates for lipase‐catalyzed esterification reactions to produce biopolyesters. For the first time, NADES composed of glycerol and an organic base/acid were used for esterification reactions catalyzed by Aspergillus oryzae lipase. High conversion rates (>70 %), containing at least 20 monomeric units of glycerol:organic acid/base were produced.
Using lipases to catalyze the synthesis of the most differentiated type of compounds remains one of the major challenges among scientists. Seeking more economic and advantageous catalysts is a ...current goal of green chemistry. In this work, we demonstrate the potential of a chemically modified form of lipase from Thermomyces lanuginosus (cmLTL) for the synthesis of both hydrophobic (heptyl heptanoate, heptyl octanoate, heptyl decanoate, decyl heptanoate, decyl octanoate and decyl decanoate) and amphiphilic (2‐(2‐ethoxyethoxy)ethyl oleate and 2‐(2‐ethoxyethoxy)ethyl linoleate) esters, in bulk. The results were compared with its native (LTL) and immobilized (imLTL) forms. The data revealed that LTL showed poor activity for all reactions performed with n‐heptane (η<20 %). ImLTL was able to synthesize all hydrophobic esters (η>60 %), with exception of the short ester, heptyl heptanoate. cmLTL was the only form of LTL capable of producing hydrophobic and amphiphilic esters, without compromising the yield when the reactions were performed under solvent‐free conditions (>50 %). Molecular modeling showed that the active pocket of cmLTL is able to deeply internalize transcutol, with stronger interactions, justifying the outstanding results obtained. Furthermore, owing to the possibility of cmLTL filtration, the reusability of the catalyst is ensured for at least 6 cycles, without compromising the reaction yields.
In this work, the potential of a chemically modified lipase was demonstrated for esterification reactions using hydrophobic and amphiphilic substrates. The enzyme displayed outstanding catalytic performance under solvent‐free conditions for all tested substrates, compared to their native and immobilized counterparts.
In this work, three deep eutectic mixtures (DES 1: choline chloride/urea; DES 2: choline chloride/glycerol; and DES 3: tetrabutylammonium bromide/imidazole) were investigated as mediums for the ...synthesis of glucose laurate and glucose acetate. Aiming to achieve a greener and more sustainable approach, the synthesis reactions were catalyzed by lipases from Aspergillus oryzae (LAO), Candida rugosa (LCR), and porcine pancreas (LPP). The hydrolytic activity of lipases against p‐nitrophenyl hexanoate revealed no evidence of enzyme inactivation when DES were used as medium. Regarding the transesterification reactions, combining LAO or LCR with DES 3 resulted in the efficient production of glucose laurate (from glucose and vinyl laurate) (conversion >60 %). The best result for LPP was observed in DES 2, with 98 % of product production after 24 hours of reaction. When replacing vinyl laurate by a smaller hydrophilic substrate, vinyl acetate, a distinct behavior was observed. LCR and LPP performed better in DES 1, yielding more than 80 % of glucose acetate after 48 hours of reaction. The catalytic activity of LAO was less pronounced, reaching only nearly 40 % of product in DES 3. The results highlight the potential of combining biocatalysis with greener and environmentally‐safer solvents, for the synthesis of differentiated chain‐length sugar fatty acid esters (SFAE).
Biocatalysis at its best! A green and sustainable methodology for the synthesis of glucose laurate and glucose acetate is presented. High conversions were obtained when combining deep eutectic solvents (choline chloride/urea; choline chloride/glycerol; or tetrabutylammonium bromide/imidazole) with lipases (from Aspergillus oryzae, Candida rugosa, or porcine pancreas).
Fluorescent quantification of melanin Fernandes, Bruno; Matamá, Teresa; Guimarães, Diana ...
Pigment cell and melanoma research,
November 2016, Letnik:
29, Številka:
6
Journal Article
Recenzirano
Odprti dostop
Summary
Melanin quantification is reportedly performed by absorption spectroscopy, commonly at 405 nm. Here, we propose the implementation of fluorescence spectroscopy for melanin assessment. In a ...typical in vitro assay to assess melanin production in response to an external stimulus, absorption spectroscopy clearly overvalues melanin content. This method is also incapable of distinguishing non‐melanotic/amelanotic control cells from those that are actually capable of performing melanogenesis. Therefore, fluorescence spectroscopy is the best method for melanin quantification as it proved to be highly specific and accurate, detecting even small variations in the synthesis of melanin. This method can also be applied to the quantification of melanin in more complex biological matrices like zebrafish embryos and human hair.
Abstract Rheumatoid arthritis (RA) is the most common inflammatory rheumatic disease, affecting almost 1% of the world population. Although the cause of RA remains unknown, the complex interaction ...between immune mediators (cytokines and effector cells) is responsible for the joint damage that begins at the synovial membrane. Activated macrophages are critical in the pathogenesis of RA and have been shown to specifically express a receptor for the vitamin folic acid (FA), folate receptor β (FRβ). This particular receptor allows internalization of FA-coupled cargo. In this review we will address the potential of nanoparticles as an effective drug delivery system for therapies that will directly target activated macrophages. Special attention will be given to stealth degree of the nanoparticles as a strategy to avoid clearance by macrophages of the mononuclear phagocytic system (MPS). This review summarizes the application of FA-target nanoparticles as drug delivery systems for RA and proposes prospective future directions.
For years, silk fibroin of a domestic silkworm, Bombyx mori, has been recognized as a valuable material and extensively used. In the last decades, new application fields are emerging for this ...versatile material. Those final, specific applications of silk dictate the way it has been processed in industry and research. This review focuses on the description of various approaches for silk downstream processing in a laboratory scale, that fall within several categories. The detailed description of workflow possibilities from the naturally found material to a finally formulated product is presented. Considerable attention is given to (bio‐) chemical approaches of silk fibroin transformation, particularly, to its enzyme‐driven modifications. The focus of the current literature survey is exclusively on the methods applied in research and not industry.
A vast piece of literature, describing various methods for silk fibroin lab‐scale processing, is currently found. For this reason different reviews, based on several grouping strategies (i.e., silk‐based hydrogels, silk‐derived devices for controlled release, etc.) exist. The purpose of the present survey is to unite a variety of physical, chemical, and enzymatic approaches of fibroin processing, regardless of their final product destination.
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•Stable and nanosized protein-based nanoparticles with entrapped vitamin E.•Pad-cure coating of fabrics with nanoparticles confer antioxidant activity.•A method to test transfer and ...release of coating was assessed.
In the present study, we coated cotton fabrics with protein-based nanoparticles containing vitamin E (α-tocopherol) by the pad-cure method. Scanning electron microscopy, Fourier transform infra-red spectroscopy, and air permeability analysis of coated samples confirmed the fixation of the nanoparticles onto the fabric’s surface. The antioxidant activity of the coated fabrics was evaluated by 2,2′-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) free radicals reduction. Samples coated with nanoparticles containing the highest amount of encapsulated vitamin E (20% of the oil phase) showed the highest antioxidant activity. The protein-based coating was maintained for at least 10 washing cycles, demonstrating the reliability of the pad-cure method for the fixation of nanoparticles onto cotton surfaces. A methodology for nanoparticles release from the coated surfaces and their transfer to other substrates was demonstrated by the simple crock meter rubbing in the presence of sweat and protease. A high amount of material can be transferred and released to other substrates, such as textiles and skin, through the synergistic effect of sweat/protease and abrasion. An array of cosmetic and medical applications are possible with the developed coating and release methodology in which vitamin E would impart vital benefits as skin protection, anti-ageing product, or skin moisturizer.
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