Cloning, Characterization, and Functional Expression of a Thermostable Type B Feruloyl Esterase from Thermophilic Thielavia Terrestris.

Feruloyl esterases (FAEs) have great potential applications in paper and breeding industry. A new thermo-stable feruloyl esterase gene, TtfaeB was identified from the thermophilic fungus Thielavia terrestris h408. Deduced protein sequence shares the identity of 67% with FAEB from Neurospora crassa. The expression vector pPIC9K-TtfaeB was successfully constructed and electro-transformed into GS115 strain of Pichia pastoris. One transformant with high feruloyl esterase yield was obtained through plate screening and named TtFAEB1. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) analysis of fermentation supernatant from transformant TtFAEB1 showed a distinct protein band appearing at the position of about 35-kDa, indicating that TtfaeB gene has been successfully expressed in P. pastoris. The recombinant TtFAEB was purified by affinity chromatography and the specific activity of purified TtFAEB was 6.06 ± 0.72 U/mg. The optimal temperature and pH for purified recombinant TtFAEB was 60 °C and 7.0, respectively. TtFAEB was thermostable, retaining 96.89 and 84.16% of the maximum activity after being treated for 1 h at 50 °C and 60 °C, respectively. Additionally, the enzyme was stable in the pH range 4.5-8.0. The homology model of TtFAEB showed that it consists of a single domain adopting a typical α/ß-hydrolase fold and contains a catalytic triad formed by Ser117, Asp201, and His260. TtFAEB in association with xylanase from Trichoderma reesei could release 77.1% of FA from destarched wheat bran. The present results indicated that the recombinant TtFAEB with excellent enzymatic properties is a promising candidate for potential applications in biomass deconstruction and biorefinery.

Preparation and antibacterial activity of lysozyme and layered double hydroxide nanocomposites.

It is necessary to develop "green" disinfection technology which does not produce disinfection by-products. Lysozyme-layered double hydroxide nanocomposites (LYZ-LDHs) were prepared by intercalating LYZ in LDH for the first time. Their antibacterial activity was evaluated using staphylococcus aureus as a target. The bacteria removal mechanism was also studied. Characterization of LYZ-LDHs by X-ray diffraction and Fourier transform infrared spectroscopy indicated that LYZ was successfully intercalated in LDH, compressed and deformed without secondary structural change. LYZ-LDHs showed excellent bactericidal effectiveness against staphylococcus aureus. The antibacterial performance of LYZ-LDHs was found to be affected by the LYZ/LDH ratio and the pH of the bacteria-containing water. The bacteria removal efficiency of LYZ-LDHs with LYZ/LDH mass ratio of 0.8 was consistently above 94% over the pH range of 3-9. LYZ-LDHs adsorbed bacteria to their surface by LDH and then killed them by the immobilized LYZ. This new material integrated the bactericidal ability of LYZ and adsorption ability of LDH. Moreover, the antibacterial ability of LYZ-LDHs was persistent and not limited by the adsorption capacity.

Mechanisms for the direct electron transfer of cytochrome c induced by multi-walled carbon nanotubes.

Multi-walled carbon nanotube (MWCNT)-modified electrodes can promote the direct electron transfer (DET) of cytochrome c (Cyt c). There are several possible mechanisms that explain the DET of Cyt c. In this study, several experimental methods, including Fourier transform infrared spectroscopy, circular dichroism, ultraviolet-visible absorption spectroscopy, and electron paramagnetic resonance spectroscopy were utilized to investigate the conformational changes of Cyt c induced by MWCNTs. The DET mechanism was demonstrated at various nano-levels: secondary structure, spatial orientation, and spin state. In the presence of MWCNTs, the secondary structure of Cyt c changes, which exposes the active site, then, the orientation of the heme is optimized, revolving the exposed active center to the optimum spatial orientation for DET; and finally, a transition of spin states is induced, providing relatively high energy and a more open microenvironment for electron transfer. These changes at different nano-levels are closely connected and form a complex process that promotes the electron transfer of Cyt c.

Synthesis and properties of cordycepin intercalates of Mg-Al-nitrate layered double hydroxides.

Layered double hydroxides (LDHs) were investigated as cordycepin delivery nanocarriers for the first time in this study. Negatively charged biomolecule-cordycepin was intercalated in the gallery spaces of [Mg-Al-NO(3)] as the charge-compensating species, which was confirmed by the results of XRD, FT-IR, TEM, CZE and electrophoretic mobility. Cell experiment suggested that the new bio-LDH nanohybrid could prevent cordycepin decomposition by adenosine deaminase. This new formulation could possibly be used as a novel form cordycepin intravenous injection.