Fusion protein of Vitreoscilla hemoglobin with D-amino acid oxidase enhances activity and stability of biocatalyst in the bioconversion process of cephalosporin C

In this study we constructed an artificial flavohemoprotein by fusing Vitreoscilla hemoglobin (VHb) with D-amino acid oxidase (DAO) of Rhodotorula gracilis to determine whether bacterial hemoglobin can be used as an oxygen donor to immobilized flavoenzyme. This chimeric enzyme significantly enhanced DAO activity and stability in the bioconversion process of cephalosporin C. In a 200-mL bioreactor, the catalytic efficiency of immobilized VHb-DAO against cephalosporin C was 12.5-fold higher than that of immobilized DAO, and the operational stability of the immobilized VHb-DAO was approximately threefold better than that of the immobilized DAO. In the scaled-up bioprocess with a 5-L bioreactor, immobilized VHb-DAO (2500 U/L) resulted in 99% bioconversion of 120 mM cephalosporin C within 60 min at an oxygen flow rate of 0.2 (v/v) x min. Ninety percent of the initial activity of immobilized VHb-DAO could be maintained at up to 50 cycles of the enzymatic reaction without exogenous addition of H(2)O(2) and flavin adenine dinucleotide (FAD). The purity of the final product, glutaryl-7-aminocephalosporanic acid, was confirmed to be 99.77% by high-performance liquid chromatography (HPLC) analysis. Relative specificity of immobilized VHb-DAO on D-alpha-aminoadipic acid, a precursor in cephalosporin C biosynthesis, increased twofold, compared with that of immobilized DAO, suggesting that conformational modification of the VHb-DAO fusion protein may be altered in favor of cephalosporin C.     

Identification and characterisation of a novel splice variant of the human CB1 receptor

Cannabinoid ligands are implicated in many physiological processes and to date two receptors have been identified. However, a growing body of evidence exists that suggests the presence of additional receptors. Whilst cloning the previously described hCB1a, we have identified a novel variant that we call hCB1b. Characterising these two splice variants demonstrates that they have a unique pharmacological profile and that their RNA's are expressed at low levels in a variety of tissues.     

越南苦苣苔科植物国家级分布新记录——大苞漏斗苣苔

漏斗苣苔属(Raphiocarpus Chun)是分布于中国至中南半岛一带的小属,主要产于中国华南西南抵越南北部至中部,但之前中越两国共有分布的该属物种仅有3个种。大苞漏斗苣苔[Raphiocarpus begoniifolius(Lévl.)Burtt]一度被认为是中国的特有种,仅分布在中国的广西西北部、贵州西南部、云南东南部和湖北西北部,尚未见有在越南的相关研究报道。该文首次报道了越南植物区系中大苞漏斗苣苔的国家级分布新记录,使得中越两国共有分布的该属物种上升到了4个种,并着重讨论了大苞漏斗苣苔与其近缘种长筒漏斗苣苔[Raphiocarpus macrosiphon(Hance)Burtt]的区别特征,进一步完善了越南所分布的漏斗苣苔属植物检索表。根据中越两国的各自与联合野外考察工作对该种的濒危现状进行了讨论,为中越两国开展该种乃至该属植物的保育提供了直接证据。凭证标本保存于越南生物资源与生态研究所标本馆(HN)中。     

Self‐Assemble and In Situ Formation of Ni1−xFexPS3 Nanomosaic‐Decorated MXene Hybrids for Overall Water Splitting

Herein, the authors present the development of novel 0D–2D nanohybrids consisting of a nickel‐based bimetal phosphorus trisulfide (Ni_1?xFe_xPS₃) nanomosaic that decorates on the surface of MXene nanosheets (denoted as NFPS@MXene). The nanohybrids are obtained through a facile self‐assemble process of transition metal layered double hydroxide (TMLDH) on MXene surface; followed by a low temperature in situ solid‐state reaction step. By tuning the Ni:Fe ratio, the as‐synthesized NFPS@MXene nanohybrids exhibit excellent activities when tested as electrocatalysts for overall water splitting. Particularly, with the initial Ni:Fe ratio of 7:3, the obtained Ni_0.7Fe_0.3PS₃@MXene nanohybrid reveals low overpotential (282 mV) and Tafel slope (36.5 mV dec^?1) for oxygen evolution reaction (OER) in 1 m KOH solution. Meanwhile, the Ni_0.9Fe_0.1PS₃@MXene shows low overpotential (196 mV) for the hydrogen evolution reaction (HER) in 1 m KOH solution. When integrated for overall water splitting, the Ni_0.7Fe_0.3PS₃@MXene || Ni_0.9Fe_0.1PS₃@MXene couple shows a low onset potential of 1.42 V and needs only 1.65 V to reach a current density of 10 mA cm^?2, which is better than the all noble metal IrO₂ || Pt/C electrocatalyst (1.71 mV@10 mA cm^?2). Given the chemical versatility of Ni_1?xFe_xPS₃ and the convenient self‐assemble process, the nanohybrids demonstrated in this work are promising for energy conversion applications.     

High Efficiency (>17%) Si‐Organic Hybrid Solar Cells by Simultaneous Structural,Electrical, and Interfacial Engineering via Low‐Temperature Processes

Highly efficient organic–inorganic hybrid solar cells of Si‐poly(3,4‐ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) have been demonstrated by simultaneous structural, electrical, and interfacial engineering with low processing temperature. Si substrate has been sculpted into hierarchical structure to reduce light reflection loss and increase interfacial junction area at the same time. Regarding the electrical optimization, highly conductive organic PEDOT:PSS layer has been formulated with low sheet resistance. It is argued that the sheet resistance, rather than conductivity, is the primary parameter for the high efficiency hybrid cells, which leads to the optimization of thickness, i.e., thick enough to have low sheet resistance but transparent enough to pass the incident sunlight. Finally, siloxane oligomers have been inserted into top/bottom interfaces by contact‐printing at room ambient, which suppresses carrier recombination at interfaces and reduces contact resistance at bottom electrode. Contrary to high‐temperature doping (for the formation of front surface or back surface fields), wet solution processes or vacuum‐based deposition, the contact‐printing can be done at room ambient to reduce carrier recombination at the interfaces. The high efficiency obtained with low processing temperature can make this type of cells be a possible candidate for post‐Si photovoltaics.     

A lectin from the Asian horseshoe crabTachypleus tridentatus: purification,specificity and interaction with tumour cells

A lectin from the haemolymph of the Asian horseshoe crabTachypleus tridentatus was purified to homogeneity by affinity chromatography on Sepharose 4B-boundN-acetylneuraminic acid. The specificity of this lectin was studied by haemagglutination inhibition with sialic acid analogues,N-acetylhexosamines and glycoproteins. For the interaction with the agglutinin theN-acetyl group and the glyceryl side chain ofN-acetylneuraminic acid are important, while presence of an aglycon, specially an -glycosidically linked lactose increases affinity to the lectin. The strongest glycoprotein inhibitors were ovine as well as bovine submaxillary mucin andCollocalia mucin, all beingO-chain glycoproteins but carrying completely different carbohydrate chains. The majority ofN-chain proteins were inactive. As the lectin agglutinates human erythrocytes, but not the murine lymphoma lines Eb and ESb or the human colon carcinoma HT 29, these cancer cells apparently lack the Tachypleus tridentatus agglutinin-receptor which is present on red cells andO-chain glycoproteins.Abbreviations TTA Tachypleus tridentatus agglutinin - SDS sodium dodecyl sulfate - BSM bovine sub-maxillary mucin - VCS Vibrio cholerae sialidase - OSM ovine submaxillary mucin - WGA Wheat germ agglutinin - NeuAc N-acetylneuraminic acid.     

Development of a dual-wavelength fluorescent nanoprobe for in vivo and in vitro cell tracking consecutively

Many imaging probes have been developed for a wide variety of imaging modalities. However, no optical imaging probe could be utilized for both microscopic and whole animal imaging. To fill the gap, the dual-wavelength fluorescent imaging nanoprobe was developed to simultaneously carry both visible-range fluorescent dye and near-infrared (NIR) dye. Emission scan confirms that the nanoprobe exhibits two separate peaks with strong fluorescent intensity in both visible and NIR ranges. Furthermore, the dual-wavelength fluorescent nanoprobe has high photostability and colloidal stability, as well as long shelf-life. In vitro cell culture experiments show that the nanoprobe has the ability to label different types of cells (namely, esophageal, prostate, fibroblast and macrophage cell) for fluorescent microscope imaging. More importantly, cell tracking experiments confirm that cell migration and distribution in various organs can be tracked in real time using in vivo whole-body NIR imaging and in vitro microscopic imaging, respectively.     

Phytochemical and cytotoxic studies on the leaves of Calotropis gigantea

A new lignan, 9′-methoxypinoresinol (1), and two new glycosylated 5-hydroxymethylfurfurals, calofurfuralside A (2), and calofurfuralside B (3), together with nine known compounds (4–12) have been isolated from the active fractions, CHCl₃ (IC₅₀, 0.32 μg mL^?1) and EtOAc (IC₅₀, 0.55 μg mL^?1) fractions of the leaves of Calotropis gigantea. Their structures were elucidated based on NMR and MS data. Among the isolated compounds, compounds 1 and 9 exhibited potent cytotoxicity against PANC-1 human pancreatic cancer cell line under the normoglycemic condition with IC₅₀ values of 3.7 and 3.3 μM, respectively. 9′-Methoxypinoresinol (1) significantly inhibited the colony formation of PANC-1 cells in a concentration-dependent manner.