Chemical Modification Techniques Research Articles

Addition of αGal HyperAcute™ technology to recombinant avian influenza vaccines induces strong low-dose antibody responses

Highly pathogenic avian influenza represents a severe public health threat. Over the last decade, the demand for highly efficacious vaccines against avian influenza viruses has grown, especially after the 2013 H7N9 outbreak in China that resulted in over 600 human cases with over 200 deaths. Currently, there are several H5N1 and H7N9 influenza vaccines in clinical trials, all of which employ traditional oil-in-water adjuvants due to the poor immunogenicity of avian influenza virus antigens. In this study, we developed potent recombinant avian influenza vaccine candidates using HyperAcute™ Technology, which takes advantage of naturally-acquired anti-αGal immunity in humans. We successfully generated αGal-positive recombinant protein and virus-like particle vaccine candidates of H5N1 and H7N9 influenza strains using either biological or our novel CarboLink chemical αGal modification techniques. Strikingly, two doses of 100 ng αGal-modified vaccine, with no traditional adjuvant, was able to induce a much stronger humoral response in αGT BALB/c knockout mice (the only experimental system readily available for testing αGal in vivo) than unmodified vaccines even at 10-fold higher dose (1000 ng/dose). Our data strongly suggest that αGal modification significantly enhances the humoral immunogenicity of the recombinant influenza vaccine candidates. Use of αGal HyperAcute™ technology allows significant dose-sparing while retaining desired immunogenicity. Our success in the development of highly potent H5N1 and H7N9 vaccine candidates demonstrated the potential of αGal HyperAcute™ technology for the development of vaccines against other infectious diseases.

Protein 19F-labeling using transglutaminase for the NMR study of intermolecular interactions.

The preparation of stable isotope-labeled proteins is important for NMR studies, however, it is often hampered in the case of eukaryotic proteins which are not readily expressed in Escherichia coli. Such proteins are often conveniently investigated following post-expression chemical isotope tagging. Enzymatic 15N-labeling of glutamine side chains using transglutaminase (TGase) has been applied to several proteins for NMR studies. 19F-labeling is useful for interaction studies due to its high NMR sensitivity and susceptibility. Here, 19F-labeling of glutamine side chains using TGase and 2,2,2-trifluoroethylamine hydrochloride was established for use in an NMR study. This enzymatic 19F-labeling readily provided NMR detection of protein-drug and protein-protein interactions with complexes of about 100kDa since the surface residues provided a good substrate for TGase. The 19F-labeling method was 3.5-fold more sensitive than 15N-labeling, and could be combined with other chemical modification techniques such as lysine 13C-methylation. 13C-dimethylated-19F-labeled FKBP12 provided more accurate information concerning the FK506 binding site.

Development of expanded polytetrafluoroethylene cardiovascular graft platform based on immobilization of poly lactic-co-glycolic acid nanoparticles using a wet chemical modification technique

Expanded polytetrafluoroethylene ePTFE grafts are mostly employed to replace damaged blood vessels and to restore normal blood flow. However, the dilemma of early thrombosis, inflammation, and development of biofilms after implantation limit ePTFE long-term patency and restrict the patient’s life quality. In this study, poly lactic-co-glycolic acid (PLGA) nanoparticles were covalently immobilized on ePTFE surface for local therapeutic purposes. First, the ePTFE surface was primarily oxidized by H2O2/H2SO4 solution to create hydroxyl groups. Consequently, free amino groups were introduced onto ePTFE surface by an aminolyzation reaction of the activated hydroxyl groups using 3-aminopropyl triethoxysilane. The produced amino groups were further used as anchor sites for covalent immobilization of previously prepared PLGA nanoparticles. The functional groups originated on ePTFE surface were confirmed by FTIR analysis. Furthermore, the scanning electron microscopy visualization evidenced a homogeneous distribution pattern of the immobilized PLGA nanoparticles on the surface. The immobilized PLGA nanoparticles showed stability on ePTFE surface under blood flow mimetic conditions. Additionally, light microscopy observation confirmed the biocompatibility of mouse L929 fibroblasts on the nano-coated ePTFE graft. The cellular adhesion and growth did not reveal remarkable cytotoxicity in the tested modified ePTFE grafts.

Influence of silane‐modified Vinyl ester on the properties of Abaca fiber reinforced composites

AbstractThe versatility of the fiber reinforced composites has significantly replaced some of the sophisticated metal components in certain sectors of industries. The matrix could be altered to improve self‐properties via silane modifiers by forming chemical linkages with the matrix in harmony with the reinforcing agents. This research work is an endeavor to enhance the traits of Vinyl ester by scrutinizing the influence of silane chemical agents using Hexamethyldisiloxane (HMDS). The dispersion time and concentration of these chemicals in matrix were optimized and henceforth a natural reinforcement, Abaca fabric was incorporated to constitute Natural fiber composite via Vacuum Assisted Resin Transfer Molding (VARTM) technique. The effect of resin modification on mechanical, thermal, and physical properties of Vinyl ester/Abaca (VE/AF) composite was examined. HMDS resin modified composite showed an improvement in the mechanical and flame retardant properties when compared to the pristine composite due to the formation of siloxane bonding which is compatible with the functional groups of both the matrix and the fabric. FT‐IR and FESEM characterizations have showed imperative evidences to support the results. This investigation provides a channel for enhancing the properties of natural fiber composites via chemical modification technique.

Zero-order controlled release of BMP2-derived peptide P24 from the chitosan scaffold by chemical grafting modification technique for promotion of osteogenesis in vitro and enhancement of bone repair in vivo.

Combination of tissue-engineered bone scaffolds with cell-adhesive, osteoconductive, or osteoinductive biomolecules is a critical strategy to improve their properties that significantly influence cellular behaviors, such as adhesion, proliferation, and differentiation, which is beneficial for critical-sized bone defects repairing. However, the traditional surface modification techniques, such as physical adsorption, coating, and plasma treatment, et al, have great limitations for immobilization of bioactive molecules due to undesirable controlled delivery performance or overly complex multistep procedures. In this study, we functionalized the chitosan/hydroxyapatite (CS/HA) biomimetic composite scaffold for controlled delivery of BMP2-derived peptide (P24) by the chemical grafting modification technique: firstly, P24 was conjugated with a thiolated chitosan, chitosan-4-thiobutylamidine (CS-TBA); secondly, the resultant CS-P24 was then combined with HA to prepare CS-P24/HA scaffolds. The effect of CS-P24/HA scaffolds on bone regeneration was evaluated, along with the underlying biological mechanisms responsible in vitro and in vivo. In vitro, the controlled and sustained release of bioactive P24 could last up to 90 days, furthermore, the release profiles of CS-5%P24/HA and CS-10%P24/HA were linear and could be fitted according to zero-order kinetic model (R2=0.9929; R2=0.9757); P24 on the scaffold significantly promoted cell adhesion, proliferation, osteodifferentiation, and mineralization with synergistic effects. Bone marrow stromal cells (BMSCs) revealed spindle-shaped surface morphology, indicating the CS-P24/HA scaffolds supported cell adhesion and possessed a high proliferation rate that varied according to the P24 concentration levels. Furthermore, mRNA levels for OCN, Runx2, and collagen I were significantly up-regulated on CS-P24/HA scaffolds compared with cells grown on CS/HA scaffolds in vitro (p < 0.05). Similarly, the BMSCs exhibited a higher ALP expression and calcium deposition level on CS-P24/HA scaffolds compared with CS/HA scaffolds (p < 0.05). In vivo, osteoinductive studies revealed a significantly higher ectopic osteogenesis level of CS-10%P24/HA scaffolds in rat dorsal muscle pockets compared with that of CS/HA scaffolds. Finally, CS-P24/HA scaffolds showed superior performance in the reconstruction of rat calvarial bone defects. This novel CS-P24/HA scaffold is deemed a strong potential candidate for the repair of bone defects in human bone tissue engineering.

Towards Enhanced Performance Thin-film Composite Membranes via Surface Plasma Modification

Advancing the design of thin-film composite membrane surfaces is one of the most promising pathways to deal with treating varying water qualities and increase their long-term stability and permeability. Although plasma technologies have been explored for surface modification of bulk micro and ultrafiltration membrane materials, the modification of thin film composite membranes is yet to be systematically investigated. Here, the performance of commercial thin-film composite desalination membranes has been significantly enhanced by rapid and facile, low pressure, argon plasma activation. Pressure driven water desalination tests showed that at low power density, flux was improved by 22% without compromising salt rejection. Various plasma durations and excitation powers have been systematically evaluated to assess the impact of plasma glow reactions on the physico-chemical properties of these materials associated with permeability. With increasing power density, plasma treatment enhanced the hydrophilicity of the surfaces, where water contact angles decreasing by 70% were strongly correlated with increased negative charge and smooth uniform surface morphology. These results highlight a versatile chemical modification technique for post-treatment of commercial membrane products that provides uniform morphology and chemically altered surface properties.

Effect of substrate geometry on oil sorption capacity of raw and chemically modified jute fibre

&lt;div&gt;&lt;p&gt;&lt;em&gt;In this paper jute fibre was modified with three different chemical modification techniques namely acetylation using acetic anhydride, grafting using butyl acrylate monomer and fatty acid modification using oleic acid to increase the oil sorption capacity of the fibre. All the above modifications were carried out in fibrous as well as nonwoven form to study the effect of substrate geometry on oil sorption capacity. It was found that oil sorption capacity of the chemically modified jute fibres was higher than that of the raw fibres and in case of the chemically modified nonwoven it was much higher than the raw as well as modified loose fibres. Reusability of the modified substrates was also tested and it was found that all the substrates could be squeezed to recover oil and reused at least three times. &lt;/em&gt;&lt;em&gt;Nonwoven fabric’s substrate geometry permits easy rolling-in and rolling-out of the fabric for the recovery of the oil from the surface of the water. &lt;/em&gt;&lt;em&gt;Also these oil sorption-active materials being biodegradable can be used to substitute non-biodegradable synthetic materials in oil spill cleanup.&lt;/em&gt;&lt;/p&gt;&lt;/div&gt;

Effect of chemical and physical doping with iodine on the optical and dielectric properties of poly(vinyl chloride)

Iodination of poly(vinyl chloride) (PVC) was prepared by addition of I2 or I− through physical adsorption and chemical modification techniques forming (PVC–I2) (composite I) and (PVC–I−) (composite II), respectively.Investigations were performed using TGA, DSC, FTIR, UV–vis absorbance analyses and ac conductivity measurements. The activation energy of decomposition, ΔEd, was found to be 215.15kJ/mole and 43.1kJ/mole for PVC and composite II, respectively. Both direct and indirect optical transitions near the absorption edge are observed. Addition of I2 or I− decreases the optical energy gap for PVC. The chemical replacement of Cl− ion in PVC matrix with I− ion in composite II increases the electrical conductivity by two orders. A possible conduction mechanisms are suggested.

Enhancement of Thermo-Oxidative Stability of Vegetable Oil Based Lubricant via Chemical Modification Techniques

The rising demand for environmentally acceptable lubricant has led researchers to look to vegetable oils as an alternative to petroleum based lubricants. Vegetable oils have radically distinctive properties owing to their unique chemical structure which have greater ability to lubricate and have higher biodegradability. In spite of advantages, they are limited to inadequate thermo-oxidative stability and poor low-temperature properties which hinder their utilization. In the present study in order to produce a bio lubricant with good thermo-oxidative stability, rapeseed oil was subjected to two different chemical modification techniques viz., epoxidation method and successive transesterification method. The thermo-oxidative stability of formulated oil was analysed using Thermo Gravimetric Analysis (TGA). TGA analysis divulges that the thermo-oxidative stability of rapeseed oil was greatly improved with the epoxidation method in comparison with the successive transesterification method.

Facile preparation of superamphiphobic epoxy resin/modified poly(vinylidene fluoride)/fluorinated ethylene propylene composite coating with corrosion/wear-resistance

A robust superamphiphobic epoxy resin (EP)/modified poly(vinylidene fluoride) (MPVDF)/fluorinated ethylene propylene (FEP) composite coating has been prepared through the combination of chemical modification and spraying technique. Nanometer silica (SiO2, 2.5wt.%) and carbon nanotubes (CNTs, 2.5wt.%) were added in the coating to construct the necessary reticulate papillae structures for superamphiphobic surface. The prepared EP composite coating demonstrated high static contact angles (166°, 155°) and low sliding angles (3°, 5°) to water and glycerol, respectively. Moreover, the prepared coating can also retain superhydrophobicity under strongly acidic and alkaline conditions. The brittleness of EP can be avoided by introducing the malleable MPVDF. The wear life of the EP composite coating with 25wt.% FEP was improved to 18 times of the pure EP coating. The increased wear life of the coating can be attributed to the designed nano/micro structures, the self-lubrication of FEP and the chemical reaction between EP and MPVDF. The anti-corrosion performance of the coatings was investigated in 3.5% NaCl solution using potentiodynamic polarization. The results showed that the prepared superamphiphobic composite coating was most effective in corrosion resistance, primarily due to the barrier effect for the diffusion of O2 and H2O molecules. It is believed that this robust superamphiphobic EP/MPVDF/FEP composite coating prepared by the facile spray method can pave a way for the large-scale application in pipeline transport.

Identification of essential tryptophan in amylomaltase from Corynebacterium glutamicum

This work aims to identify essential tryptophan residue(s) of amylomaltase from Corynebacterium glutamicum (CgAM) through chemical modification and site-directed mutagenesis techniques. The recombinant enzyme expressed by Escherichia coli was purified and treated with N-bromosuccinimide (NBS), a modifying agent for tryptophan. A significant decrease in enzyme activity was observed indicating that tryptophan is important for catalysis. Inactivation kinetics with NBS resulted in pseudo first-order rate constant (kinact) of 2.31min−1. Substrate protection experiment confirmed the active site localization of the NBS-modified tryptophan residue(s) in CgAM. Site-directed mutagenesis was performed on W330, W425 and W673 to localize essential tryptophan residues. Substitution by alanine resulted in the loss of intra- and intermolecular transglucosylation activities for all mutated CgAMs. Analysis of circular dichroism spectra showed no change in the secondary structure of W425A but a significant change for W330A and W673A from that of the WT. From these results in combination with X-ray structural data and interpretation from the binding interactions in the active site region, W425 was confirmed to be essential for catalytic activity of CgAM. The hydrophobicity of this tryptophan was thought to be critical for substrate binding and supporting catalytic action of the three carboxylate residues at the active site.

Surface heterogeneity study of some reference Cu-Ag alloys using laser-induced breakdown spectroscopy

Investigation of the chemical composition, surface structure, metallurgical features, corrosion mechanism, and surface modification techniques of archeological metallic artifacts from Romans and pre-Roman times aimed to simulate the most commonly used Cu-based and Ag-based alloys. These simulated reference alloys will be used as sacrificial materials to study the most appropriate conservation materials and procedures. In the present work, laser-induced breakdown spectroscopy (LIBS) is introduced as a new validated surface mapping technique to study the micro-chemical distribution of elements in binary reference copper–silver alloy samples. Using different techniques for surface and bulk analysis, such as SEM coupled with energy-dispersive X-ray spectroscopy and X-ray diffraction, it has been proven that LIBS is a simple, sensitive, and direct technique in the determination of heterogeneity of the sample's surface. By changing the laser wavelength (λ/nm) and focal length of the used focusing lens (f/cm), different spot sizes can be obtained. It was possible to control the spatial resolution in mapping the investigated samples' surface and to achieve local chemical information. In the present work, Q-switched neodymium-doped yttrium aluminum garnet laser has been used at its fundamental wavelength 1064 nm and its second harmonic 532 nm. The studied samples were specially manufactured heterogeneous copper–silver alloys with known grain size as studied via SEM investigation. The obtained LIBS results are in good agreement with those by other analytical techniques and extend the applicability of the surface techniques to study metallic ancient objects. Copyright © 2015 John Wiley & Sons, Ltd.

Biocompatible Electromechanical Actuators Composed of Silk‐Conducting Polymer Composites

Single‐component, metal‐free, biocompatible, electromechanical actuator devices are fabricated using a composite material composed of silk fibroin and poly(pyrrole) (PPy). Chemical modification techniques are developed to produce free‐standing films with a bilayer‐type structure, with unmodified silk on one side and an interpenetrating network (IPN) of silk and PPy on the other. The IPN formed between the silk and PPy prohibits delamination, resulting in a durable and fully biocompatible device. The electrochemical stability of these materials is investigated through cyclic voltammetry, and redox sensitivity to the presence of different anions is noted. Free‐end bending actuation performance and force generation within silk‐PPy composite films during oxidation and reduction in a biologically relevant environment are investigated in detail. These silk–PPy composites are stable to repeated actuation, and are able to generate forces comparable with natural muscle (&gt;0.1 MPa), making them ideal candidates for interfacing with biological tissues.

Synthesis and characterization of lignin-based carbon materials with tunable microstructure

Lignin-based carbons can be used as a low-cost alternative to graphite and petroleum-based carbons enabling the production of sustainable, functional carbon materials for various applications. The microstructure development of these carbons can be controlled through chemical modification of the lignin precursor and choice of carbonization parameters. In this work, microstructured carbon materials are synthesized from lignin using a combination of chemical modification and carbon fiber processing techniques. Lignin is modified by incorporating different ester groups which results in a precursor highly compatible with melt processing using the fiber extrusion technique and conversion into microstructured carbons by oxidative stabilization and subsequent carbonization. Furthermore, the impact of esterifications on precursor chemistry and carbonizations is investigated. A nuclear magnetic resonance study of modified lignins shows characteristic spectral changes as a result of esterifications. Ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry shows the modification process does not affect the polymeric character of the lignin backbone. Esterifications result in moderate shifts in O : C and H : C ratios. Thermogravimetric analysis of lignins reveals distinct differences in mass loss trends during oxidations and carbonizations.

A Review on the Effect of Crumb Rubber Addition to the Rheology of Crumb Rubber Modified Bitumen

Crumb rubber modification has been proven to enhance the properties of pure bitumen. This paper looks at some of the international standards for producing crumb rubber modified bitumen (CRMB) and reviews the effect of crumb rubber to the rheology of crumb rubber modified bitumen. The review shows that the rheology of CRMB depends on internal factors such as crumb rubber quantity, particle size, and pure bitumen composition, and external factors such as the mixing time, temperature, and also the modification technique. These factors govern the swelling process of crumb rubber particles that lead to the increase of viscosity of the modified bitumen. However, the mixing temperature and duration can cause rubber particles to depolymerize and subsequently cause loss of viscosity. Crumb rubber modification also improves the properties of bitumen by increasing the storage and loss modulus and enhancing the high and low temperature susceptibility. The effect of crumb rubber to aging properties of CRMB is also discussed. Finally several techniques of chemical modification to terminal blends of CRMB and the subsequent improvement to the settling property of CRMB are explained.

Optimizing the Identification of Citrullinated Peptides by Mass Spectrometry: Utilizing the Inability of Trypsin to Cleave after Citrullinated Amino Acids

Citrullinated proteins have been associated with several diseases and citrullination can most likely function as a target for novel diagnostic agents and unravel disease etiologies. The correct identification of citrullinated proteins is therefore of most importance. Mass spectrometry (MS) driven proteomics can with bottom up strategies analyze protein profiles and PTMs in complex samples. However, the site-specific characterization of citrullination using MS remains problematic, especially in complex samples where no sensitive chemical modification technique exists. A tryptic missed cleavage after citrulline is therefore often used as a marker for citrullination post processing. However, C-terminal tryptic citrullinated peptides have also been reported. In this study, we therefore aimed at optimizing the identification of citrullinated peptides in complex samples. To assess the cleavage properties of trypsin, digestion was performed on synthetic peptide sets containing either arginine or citrulline. The peptide sequences originated from disease-associated in vivo citrullinated proteins; some reported as being C-terminal tryptic citrullinated peptides. Furthermore, the proteolytic activity was verified using digested synovial fluid samples from a rheumatoid arthritis patient. The samples were analyzed using liquid chromatography/tandem MS with electrospray ionization. Our in vivo and in vitro studies clearly demonstrate the inability of trypsin to cleave after citrulline residues. Based on our findings, we present a strategy for verifying citrullinated sites in complex samples post processing, in proteomics shotgun experiments. By requiring a missed cleavage for the identification of citrullinated peptides, we demonstrate that 64% of false-positively annotated citrullination sites could be removed. We furthermore demonstrated likely pitfalls of applying the strategy. In conclusion, manual annotation of citrullinated peptide spectra remains essential to ensure correct annotation. Implementing a missed cleavage requirement significantly reduces the number of spectra needing manual verification with minimal loss. This method may help future proteomics studies identify citrullinated proteins in complex samples.

Characterization of sodium starch glycolate prepared using reactive extrusion and its comparisons with a commercial brand VIVASTAR®P

Reactive extrusion is a popular technique for chemical modification of starches. In this study, the physical, chemical and morphological properties of sodium starch glycolate, prepared using reactive extrusion (SSG), were compared with those of VIVASTAR®P. As measured by sieve analysis, VIVASTAR®P had a larger weight fraction in the particle size range of 0–38μm compared to SSG. The sodium assays of VIVASTAR®P and its particle size fractions (0–38μm and 38–75μm) were found to be significantly lower than those of SSG and its particle size fractions (0–38μm, 38–75μm and 75–106μm). The NaCl content, pH, settling volume, bulk density, tap density and Carr index for VIVASTAR®P and SSG were measured. X-ray diffraction patterns indicated substantial loss of crystallinity of starch in both VIVASTAR®P and SSG. The water uptakes of the 0–38μm and 38–75μm fractions of VIVASTAR®P, measured at 20 and 180s, were significantly higher than those for the 0–38μm and 38–75μm fractions of SSG. However, no differences were found between the water uptakes of both the VIVASTAR®P fractions and the 75–106μm fraction of SSG at 20s. However, the water uptake of the SSG 75–106μm fraction leveled off as time progressed. When, 0.1N HCl was used, at an interval of 20s, the SSG 75–106μm and 38–75μm fractions had significantly higher liquid uptake than VIVASTAR®P and its 0–38μm fraction. However, no significant differences were found between the liquid uptakes of the SSG 75–106μm and 38–75μm fractions and the VIVASTAR®P 38–75μm fraction. After a time interval of 180s, the liquid uptakes of the SSG 75–106μm and 38–75μm fractions were significantly lower than those for VIVASTAR®P and its 0–38μm fraction. The liquid uptake of the VIVASTAR®P 38–75μm fraction was higher than that of the SSG 38–75μm fraction but not significantly different from the SSG 75–106μm fraction. The microstructure of VIVASTAR®P revealed the presence of spherical and ovoid shaped particles with smooth surfaces. This was in contrast with the irregular shaped particles of SSG with jagged surfaces.

Gender Bias in Skin Cancer: Role of Catalase Revealed

Sullivan et al. describe their finding that lower skin catalase activity in male as compared with female mice may be responsible for the increased skin carcinogenesis observed in UVB radiation-exposed male mice. This adds to the growing literature that points toward a gender bias in the pathogenesis of skin cancer. Delineating the events between UV exposure and carcinogenesis in relation to skin's antioxidant activity will provide insight into disease progression, prognosis, and responses to therapy. If substantiated with further studies in humans, this information may aid in designing gender-specific preventive measures aimed at reversing immune suppression through targeting the altered redox status in UV-exposed individuals.

Chemically Modified Gelatin as Biomaterial in the Design of New Nanomedicines

The synthesis of new polymers has led to dramatic enhancements in the medical field. In particular, new chemical entities provided new prospects in tissue engineering, cellular therapy and drug delivery. However, significant efforts still need to be taken in consideration in order to achieve diverse clinical applications in these fields, which is challenging because of the lack of suitable materials with desired microstructure, permeability, degradation rates, products, and suitable mechanical properties. For these reasons some chemical strategies are focused in back to the nature approaches or, in other words, in improving the properties of natural polymers by chemical modifications. We report that by using a simple chemical modification technique we can obtain new biomaterials, specifically suitable for biomedical applications. Concretely, we describe the chemical modification of gelatin and the suitable characteristics of the modified protein to develop new nanomedicines. This protein was selected because of its enormous potential in biomedicine, which is currently limited due to the difficulty of its use without toxic chemical crosslinkers. The modification of the protein was based on the transformation of the carboxylic group into amido groups after their reaction with polyamines, leading to a positively charged biopolymer. To cationize the gelatin two polyamines where used: ethylenediamine and spermine, the latter being one of the endogenous polyamines which has a very positive influence over cells. This modification was monitored by physico-chemical techniques such as NMR, spectrophotometry and potentiometry. With the most promising modified gelatins we were able to develop nanoparticles using the ionotropic gelation technique. In order to determine the ability of these new nanosystems to associate bioactive molecules we selected a model plasmid DNA. The developed nanosystems were characterized corroborating their ability to associate the genetic material. In conclusion, we were able to obtain a semi-synthetic biomaterial with tunable physico-chemical properties, which can be used to develop new nanosystems with the ability to associate genetic material. We therefore propose that the gelatin, with its chemical modification, provide a unique biomaterial for the development of new nanomedicines.

Determination of a catalytic tyrosine in Trametes cervina lignin peroxidase with chemical modification techniques

Trametes cervina lignin peroxidase (LiP) lacks a catalytic tryptophan strictly conserved in other LiP and versatile peroxidases. It contains tyrosine(181) at the potential catalytic site. This protein and the well-characterized Phanerochaete chrysosporium LiP with the catalytic tryptophan(171) have been chemically modified: the tryptophan-specific modification with N-bromosuccinimide sufficiently disrupted oxidation of veratryl alcohol by P. chrysosporium LiP, whereas the activity of T. cervina LiP was not affected, suggesting no catalytic tryptophan in T. cervina LiP. On the other hand, the tyrosine-specific modification with tetranitromethane did not affect the activities of P. chrysosporium LiP lacking tyrosine but inactivated T. cervina LiP due to the nitration of tyrosine(181). These results strongly suggest that tyrosine(181) is at the catalytic site in T. cervina LiP.