查看更多>>摘要：? 2022 Elsevier B。V。Amylose-oleic acid complexes (AOA) were exposed to microwave heat-moisture treatment (M-HMT) with different moisture content (MC)， and the variations in structures and digestibility were investigated。 M-HMT caused the dissociation of helical structures and destruction of short-range molecular order of AOA。 Meanwhile， the molecules of amylose and oleic acid rearranged and more amylose-oleic acid complexes were formed during M-HMT， the complexing index of AOA was increased from 25。41 % to 41。20 % when treating at 35 % MC。 Moreover， the relative content of single helix increased with increasing MC， resulting in higher V-type relative crystallinity。 With ≥30 % MC， the treated complexes showed greater thermostability than that of original AOA。 The treatment increased the enzymatic digestibility of AOA， and sample treated with 35 % MC had the highest resistant starch content of 82。33 %， which was 17。96 % higher than that of native AOA。 The improved enzyme resistance should be correlated to increased molecular interplay and formation of amylose-oleic acid complexes。
查看更多>>摘要：? 2022The formidable virulence of methicillin-resistant staphylococcus aureus (MRSA) have thrown great challenges to biomedicine， which mainly derives from their autocrine phenol-soluble modulins (PSMs) toxins， especially the most toxic member termed phenol-soluble modulins α3 (PSMα3)。 PSMα3 cytotoxicity is attributed to its amyloidal fibrillation and subsequent formation of cross-α sheet fibrils。 Inspired by the multiple biological activity of Sappanwood， herein， we adopted brazilin， a natural polyphenolic compound originated from Caesalpinia sappan， as a potential antidote of PSMα3 toxins， and attempted to prove that the regulation of PSMα3 fibrillation was an effective alexipharmic way for MRSA infections。 In vitro results revealed that brazilin suppressed PSMα3 fibrillation and disassembled preformed amyloidal fibrils in a dose-dependent manner， in which molar ratio (brazilin: PSMα3) of efficient inhibition and disassembly were both 1:1。 These desired regulations dominated by brazilin benefited from its bonding to core fibrils-forming residues of PSMα3 monomers urged by hydrogen bonding and pi-pi stacking， and such binding modes facilitated brazilin-mediated inhibition or disruption of interactions between neighboring PSMα3 monomers。 In this context， these inhibited and disassembled PSMα3 assemblies could not easily insert into cell membrane and subsequent penetration， and thus alleviating the membrane disruption， cytoplasmic leakage， and reactive oxygen species (ROS) generation in normal cells。 As such， brazilin dramatically decreased the cytotoxicity borne by toxic PSMα3 fibrils。 In addition， in vivo experiments affirmed that brazilin relieved the toxicity of PSMα3 toxins and thus promoted the skin wound healing of mice。 This study provides a new antidote of PSMα3 toxins， and also confirms the feasibility of the assembly-regulation strategy in development of antidotes against supramolecular fibrillation-dependent toxins。
查看更多>>摘要：? 2022 Elsevier B。V。Here， we report the characterization (purification， autoxidation rate， pseudoperoxidase activity) and amino acid sequence determination of S。 scombrus (Atlantic mackerel) and S。 colias (Tinker mackerel) mioglobins (Mbs)， considering the increasing consumption of fresh and canned mackerel meat and Mb implication in meat storage (e。g。: browning and lipid oxidation)。 We found that Atlantic mackerel Mb has major autoxidation rate (0。204 ± 0。013 h?1) compared to Tinker mackerel Mb (0。140 ± 0。009 h?1)， while the pseudoperoxidase activity is major for Tinker mackerel (Km: 87。71 ± 7。19 μM; kcat: 0。32 s?1) Mb with respect to Atlantic mackerel (Km: 96。08 ± 6。91 μM; kcat: 0。50 s?1)。 These functional differences are confirmed by primary structure determination， in which six amino acid substitutions are found， with the first N-terminal amino acid residue acetylated。 Furthermore， we predicted by AphaFold 3D model both fish Mbs and used them to investigate the possible structural differences。 In addition， phylogenetic analysis using Mb sequences from Scombridae family confirms that Atlantic and Tinker mackerels are two distinct species。 Finally， an analytic qualitative RP-HPLC method to distinguish S。 scombrus and S。 colias specimens was developed considering the different retention times of the two mackerel apoMbs。
查看更多>>摘要：? 2022 Elsevier B。V。Here we reported the fabrication of an electrospun membrane based on a hyaluronic acid derivative (HA-EDA) to be used as a bandage for the potential treatment of chronic wounds。 The membrane， loaded with graphene oxide (GO) and ciprofloxacin， showed photothermal properties and light-triggered drug release when irradiated with a near-infrared (NIR) laser beam。 Free amino groups of HA-EDA derivative allowed autocrosslinking of the electrospun membrane; thus， a substantial enhancement in the hydrolytic resistance of the patch was obtained。 In vitro antibacterial activity studies performed on Staphylococcus aureus and Pseudomonas aeruginosa revealed that such electrospun membranes， due to the synergistic effect of the antibiotic and NIR-mediated hyperthermia， reduced the viability of both pathogens。 Specific in vitro experiment demonstrated also that is possible to disrupt， through laser irradiation， the biofilms formed onto the membrane。
查看更多>>摘要：? 2022There are many different grafts to repair damaged tissue。 Various types of biological scaffolds， including films， fibers， microspheres， and hydrogels， can be used for tissue repair。 A hydrogel， which is composed a natural or synthetic polymer network with high water absorption capacity， can provide a microenvironment closely resembling the extracellular matrix (ECM) of natural tissues to stimulate cell adhesion， proliferation， and differentiation。 It has been shown to have great application potential in the field of tissue repair and regeneration。 Hydrogels derived from natural tissues retain a variety of proteins and growth factors in optimal proportions， which is beneficial for the regeneration of specific tissues。 This article reviews the latest research advances in the field of hydrogels from a variety of natural tissue sources， including bone tissue， blood vessels， nerve tissue， adipose tissue， skin tissue， and muscle tissue， including preparation methods， advantages， and applications in tissue engineering and regenerative medicine。 Finally， it summarizes and discusses the challenges faced by natural tissue-derived hydrogels used in tissue repair， as well as future research and application directions。
查看更多>>摘要：? 2022Isoprenoids represent the largest group of natural products， whose basal skeletons are synthesized by various isoprenyl diphosphate synthases (IDSs)。 As majority of IDSs catalyze head-to-tail reaction to produce linear form isoprenoids， some catalyze head-to-middle reaction to produce branched form products。 In a previous study， an IDS termed MA1831 from Methanosarcina acetivorans was found to be capable of catalyzing both types of reaction。 In addition to the canonical linear product of C35 in length， MA1831 also catalyzes head-to-middle condensation of farnesyl diphosphate (FPP) and dimethylallyl diphosphate (DMAPP) to produce geranyllavandulyl diphosphate。 In order to investigate the mechanism of action of MA1831， we determined its crystal structures in apo-form and in complex with substrates and analogues。 The complex structures that contain isopentenyl S-thiolodiphosphate and DMAPP as homoallylic substrates were also reported， which should represent the reaction modes of MA1831-mediated head-to-tail and head-to-middle reaction， respectively。 Based on the structural information， the mechanism of MA1831 catalyze head-to-tail and head-to-middle condensation reaction was proposed。
查看更多>>摘要：? 2022 Elsevier B。V。We performed a robust characterization of the molecular interactions between the DNA molecule and two imidazolium-based ionic liquids (ILs): 1-Butyl-3-methylimidazolium chloride ([bmim]Cl) and 1-Octyl-3-methylimidazolium chloride ([omim]Cl)， using single molecule approaches (optical and magnetic tweezers) and bulk techniques (isothermal titration calorimetry and conductivity measurements)。 Optical and magnetic tweezers allowed us to obtain the changes on the mechanical properties of the DNA complexes formed with both ILs， as well as the relevant physicochemical (binding) parameters of the interaction。 Despite the weak binding measured between DNA and the two ILs， we identify a transition on the regime of polymer elasticity of the complexes formed， which results in a relevant DNA compaction for high IL concentrations。 In addition， isothermal titration calorimetry and conductivity complemented the single molecule investigation， giving a complete thermodynamic characterization of the interactions and allowing the identification of the most relevant driving forces at various different concentration ranges of the ILs。 Based on the results obtained with all the employed techniques， we propose a model for the binding schemes involving DNA and both [bmim]Cl and [omim]Cl。
查看更多>>摘要：? 2022 Elsevier B。V。In this work， multi-fluid mixing solution blow spinning was applied to develop gelatin/pullulan composite nanofibers， and then the nanofibers were glycated to enhance the physical properties。 The results show that the grafting degree of the nanofibers increased significantly from 17。5 % to 36。0 % as the glycation time increased， and the morphology results indicated that 72 h of glycation did not destroy the structure of the nanofibers。 FTIR results show that the glycation consumed the the–NH2 groups， cleaved sugar units of polysaccharide， and affected the secondary structure of the protein。 The glycation enhanced the thermal stability and improved the rigidity of the nanofibers。 Besides， after 120 h of glycation， the water contact angle of nanofibers increased from 0° to 79。1°， and the water vapor transmission rates decreased from 12。49 to 8。97 g mm/m2 h kPa， indicating the enhanced hydrophobicity and barrier properties。 In addition， the glycation improved the water stability of the nanofibers， which increased the applicability of the gelatin/pullulan nanofibers in food packaging。 The present work provides a green and efficient method for improving the physical properties of gelatin/pullulan nanofibers。
查看更多>>摘要：? 2022Structural evolution， digestibility and inhibition on starch digestion of rice glutelin fibril aggregates (RGFAs) as affected by incubation were investigated。 Thioflavin T fluorescence intensity of the RGFAs， incubated for 4-day， reached the maximum values， which ranged from 845。00 ± 23。52 to 873。67 ± 50。30。 Transmission electron microscopy (TEM) observed that the samples heated for 2 h (2 h fibril) were self-assembled from small glutelin aggregates and a few protofibrils into mature fibrils， the samples heated for 4–10 h (4–10 h fibril) were elongated into long， branched fibrils， and the longer fibrils of 15 h fibril sample dissociated into short fibrils after 4-day of incubation。 Compared to rice glutelin， the RGFAs showed thermal stability and resistance to proteolysis。 The fluorescence retention rate of 6 h fibril， after incubation for 4-day， was 8。62 ± 0。61 % after in vitro stomach and pancreas digestion， which was the highest among all of the samples。 The RGFAs incubated for 1-day displayed much better inhibition effects on starch digestion。 This was the first study to clarify the relationship between incubation and physicochemical/functional properties of protein fibrils， which could help understand the preservation of food protein fibrils and their application。
Belo A.A.Naves de Souza D.L.de Melo-Braga M.N.Lopes de Souza L....
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查看更多>>摘要：? 2022 Elsevier B。V。Accidents with snakes from the genus Bothrops represent ~90 % of all snakebites in Brazil。 Monoclonal antibodies (mAbs) targeting venom components can be important assets for treating envenoming syndromes， for developing diagnostic tests and for research purposes。 Therefore， in this study， we aimed to generate murine mAbs against the antigenic mixture of Bothropic venoms traditionally used as immunogen to produce Bothropic antivenoms in Brazil。 ELISA showed that one of the produced mAbs recognizes B。 alternatus and B。 neuwiedi venoms (mAb anti-Ba/Bn) specifically and Western Blot revealed that this mAb binds to a single protein band of molecular mass of ≈50 kDa。 MAb anti-Ba/Bn inhibited the coagulant activity but was unable to neutralize hemorrhagic and phospholipase A2 activities caused by the B。 neuwiedi venom。 MAb anti-Ba/Bn was immobilized to Sepharose beads and used for immunoaffinity chromatography of B。 neuwiedi venom。 Proteolytic activity assays indicated that the immunoaffinity-purified fraction (BnF-Bothrops neuwiedi fraction) has a serine protease thrombin-like profile， which was supported by coagulability assays in mice。 Bottom-up proteomic analysis confirmed the prevalence of serine proteases in BnF using label-free quantification。 In conclusion， this work characterized a mAb with neutralizing properties against B。 neuwiedi coagulant activity and demonstrates that immunoaffinity chromatography using mAbs can be a useful technique for purification of bioactive toxic proteins from Bothrops spp。 snake venoms。
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