Characterization of three fibrinogenolytic enzymes from Chinese green tree viper (Trimeresurus stejnegeri) venom

Rong Gao, Yun Zhang, Qing-Xiong Meng, Wen-Hui Lee, Dong-Sheng Li, Yu-liang Xiong and Wan-Yu Wang. Characterization of three fibrinogenolytic enzymes from Chinese green tree viper (Trimeresurus stejneger ) venom. Toxicon 36, 457-467, 1998.-From the venom of Chinese green tree viper (Trimeresurus stejnegeri), three distinct fibrinogenolytic enzymes: stejnefibrase-l, stejnefibrase-2 and stejnefibrase-3, were purified by gel filtration, ion-exchange chromatography and reverse-phase high-performance chromatograghy (HPLC). SDS-PAGE analysis of those three enzymes showed that they consisted of a single polypeptide chain with mel. wt of -50 000, 31 000 and 32 000, respectively. Like TSV-PA (a specific plasminogen activator) and stejnobin (a fibrinogen-clotting enzyme) purified from the same venom, stejnfibrase-1, -2 and -3 were able to hydrolyze several chromogenic substrate. On the other hand, different from TSV-PA. and stejnobin, stejnefibrase-l, -2 and -3 did not activate plasminogen and did not possess fibrinogen-clotting activity. The three purified enzymes directly degraded fibrinogen to small fragments and rendered it unclottable by thrombin. Stejnefibrase-2 degraded preferentially BE-chain while stejnefibrase-l and -3 cleaved concomitantly Ax and B beta-chains of fibrinogen. None of these proteases degraded the gamma-chain of fibrinogen. When correlated with the loss of clottability of fibrinogen, the most active enzyme was stejnefibrase-l. The activities of the three enzymes were inhibited by phenylmethylsulfonyl fluoride (PMSF) and p-nitrophenyl-p-guanidinobenzoate (NPGB), indicating that like TSV-PA and stejnobin, they are venom serine proteases. (C) 1998 Elsevier Science Ltd. All rights reserved.

Molecular and functional characterization of a c-type lysozyme from the Asian corn borer, Ostrinia furnacalis

Some lepidopteran lysozymes have been reported to display activity against Gram-positive and Gram-negative bacteria, in contrast to most lysozymes that are active only against Gram-positive bacteria. OstrinLysC, a c-type lysozyme, was purified from the As

Anti Human Immunodeficiency Virus-1 (HIV-1) Agents 3. Synthesis and in Vitro Anti-HIV-1 Activity of Some N-Arylsulfonylindoles

In order to find compounds with superior anti human immunodeficiency virus type 1 (HIV-1) activity, twelve simple N-arylsulfonylindoles (3a-1) were synthesized and preliminarily evaluated as HIV-1 inhibitors in vitro for the first time. Several compounds

Anti HIV-1 Agents 2. Discovery of Dibenzofurans as New HIV-1 Inhibitors In Vitro

Ten dibenzofurans were synthesized and evaluated as human immunodeficiency virus (HIV)-1 inhibitors in vitro for the first time. Among these compounds, compounds 1, 6, 7 and 8 demonstrated significant anti-HIV-1 activity. Especially compound 1 showed the

Anti Human Immunodeficiency Virus-1 (HIV-1) Agents 1. Discovery of Benzyl Phenyl Ethers as New HIV-1 Inhibitors in Vitro

Ten single benzyl phenyl ethers were synthesized and evaluated as human immunodeficiency virus-1 (HIV-1) inhibitors in vitro for the first time. Among these compounds, especially 4-nitrobenzyl phenyl ether (3h) exhibited the highest anti-HIV-1 activity wi

Elevated levels of urinary 8-hydroxy-2'-deoxyguanosine in male electrical and electronic equipment dismantling workers exposed to high concentrations of polychlorinated dibenzo-p-dioxins and dibenzofurans, polybrominated diphenyl ethers, and polychlorinated biphenyls

To investigate the occupational exposure levels to polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polybrominated diphenyl ethers (PBDEs), and polychlorinated biphenyls (PCBs), indoor dust (n = 3) in workshops and hair samples from male workers (n = 64) were collected at two electrical and electronic equipment waste (E-waste) dismantling factories located in the LQ area in east China in July 11-13, 2006. Pre- and postworkshift urines (64 of each) were also collected from the workers to study oxidative damage to DNA using 8-hydroxy-2'-deoxyguanosine (8-OHdG) as a biomarker. The concentrations of PCDD/Fs, PCDD/F-WHO-TEQs, PBDEs, PCBs and PCB-WHO-TEQs were (50.0 +/- 8.1) x 10(3), 724.1 +/- 249.6, (27.5 +/- 5.8) x 10(6), (1.6 +/- 0.4) x 10(9), (26.2 +/- 3.0) x 10(3) pg/g dry weight (dw) in dust, and (2.6 +/- 0.6) x 10(3), 42.4 +/- 9.3, (870.8 +/- 205.4) x 10(3), (1.6 +/- 0.2) x 10(6), 41.5 +/- 5.5 pg/g dw in hair, respectively. The homologue and congener profiles in the samples demonstrated that high concentrations of PCDD/Fs, PBDEs, and PCBs were originated from open burning of E-waste. The 8-OHdG levels were detected at 6.40 +/- 1.64 mu mol/mol creatinine in preworkshift urines. However, the levels significantly increased to 24.55 +/- 5.96 mu mol/mol creatinine in postworkshift urines (p < 0.05). Then, it is concluded that there is a high cancer risk originated from oxidative stress indicated by the elevated 8-OHdG levels in the E-waste dismantling workers exposed to high concentrations of PCDD/Fs, PBDEs, and PCBs.

Fabrication and performance of an index-coupled DFB laser with sampled grating

An index-coupled DFB laser with a sampled grating has been designed and fabricated. The key concept of the approaches is to utilize the +1st-order reflection of the sampled grating for laser operation, and use a conventional holographic exposure combined with the usual photolithography to form the sampled grating. The typical threshold current of the sampled grating DFB laser is 25 mA, and the optical output is about 10 mW at the injected current of 100 mA. The lasing wavelength of the device is 1.5314 mu m, which is the +1st-order peak of the sampled grating.

Calculation of energy levels in InGaAs/GaAs quantum dot array

The subbands of the ground state E-c1, the first excited state E-c2 and heavy hole state E-HH1 are calculated by solving the eigenvalues of effective-mass Hamiltonian H-0 which is derived from eight-band k . p theory and the calculations are performed at k(x) = k, = k = 0 for the three-dimensional array of InGaAs/GaAs quantum dots (QDs). With indium content in InGaAs QDs gradually increasing from 30% to 100%,the intersubband transition wavelength of E-c2 to E-c1, blue-shifts from 18.50 to 11.87 mu m,while the transition wavelength of E-c1, to E-HH1, red-shifts from 1. 04 to 1. 73 mu m. With the sizes of Ir-0.5 Ga-0.5 As and InAs QDs increasing from 1.0 to 5.0 nm, the intersubband transition from E-c1, to E-C2 transforms from bound-state-to-continuum-state to bound-state-to-bound-state, and the corresponding intersubband transition wavelengths red-shift from 8.12 pm (5.90 pm) to 53.47 mu m (31.87 pm), respectively, and the transition wavelengths of E-C1 to E-HH1 red-shift from 1. 13 mu m (1.60 mu m) to 1.27 mu m (2.01 mu m), respectively.

Influence of GaAsP insertion layers on performance of InGaAsP/InGaP/AlGaAs quantum-well laser

We report on the use of very thin GaAsP insertion layers to improve the performance of an InGaAsP/InGaP/AlGaAs single quantum-well laser structure grown by metal organic chemical vapour deposition. Compared to the non-insertion structure, the full width at half maximum of photoluminescence spectrum of the insertion structure measured at room temperature is decreased from 47 to 38 nm indicating sharper interfaces. X-ray diffraction shows that the GaAsP insertion layers between AlGaAs and InGaP compensates for the compressive strain to improve the total interface. The laser performance of the insertion structure is significantly improved as compared with the counterpart without the insertion layers. The threshold current is decreased from 560 to 450mA while the slope efficiency is increased from 0.61 to 0.7W/A and the output power is increased from 370 to 940mW. The slope efficiency improved is very high for the devices without coated facets. The improved laser performance is attributed to the suppression of indium carry-over due to the use of the GaAsP insertion layers.

Theoretical analysis of modal gain in p-doped 1.3 mu m InAs/GaAs quantum dot lasers

A theoretical study of modal gain in p-doped 1.3 mu m InAs/GaAs quantum dot (QD) lasers is presented. The expression of modal gain is derived, which includes an effective ratio that describes how many QDs contribute to the modal gain. The calculated results indicate that the modal gain with the effective ratio is much smaller than that without the effective ratio. The calculated maximum modal gain is is a good agreement with the experimental data. Furthermore, QDs with lower height or smaller aspect ratio are beneficial in achieving a larger maximum modal gain that leads to lower threshold current density and higher differential modal gain. (C) 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Delay of the excited state lasing of 1310 nm InAs/GaAs quantum dot lasers by facet coating

In this letter, we present a facet coating design to delay the excited state (ES) lasing for 1310 nm InAs/GaAs quantum dot lasers. The key point of our design is to ensure that the mirror loss of ES is larger than that of the ground state by decreasing the reflectivity of the ES. In the facet coating design, the central wavelength is at 1480 nm, and the high- and low-index materials are Ta2O5 and SiO2, respectively. Compared with the traditional Si/SiO2 facet coating with a central wavelength of 1310 nm, we have found that with the optimal design the turning temperature of the ES lasing has been delayed from 90 to 100 degrees C for the laser diodes with cavity length of 1.2 mm. Furthermore, the characteristic temperature (T-0) of the laser diodes is also improved.