Contribution of blotting techniques to the study of rapeseeds (Brassica napus L.) lipases

A recent advance in the study of plant lipases involving immunological techniques is presented. In an attempt to characterize lipases of cotyledons from germinating rapeseed seedlings and to investigate an eventual cross-reactivity with animal lipases, we have prepared anti-porcine pancreatic lipase antibodies raised in rabbit. It is shown by enzyme-linked immunosorbent assay and dot-blotting that these antibodies react with lipases in the rapeseed crude extract and in the different cellular fractions obtained by differential centrifugation. Preincubation of the antiserum with the rapeseed crude extract affects the amount of antibodies binding to the porcine pancreatic lipase. We demonstrate immunochemical cross-reactivity between rapeseed and porcine pancreatic lipase. Using the immunoblotting procedure, it is found that antibodies bind specifically to a single polypeptide with a molecular mass of about 55 kDa. Rapeseed lipase activity decreased after immunoprecipitation suggesting that antibodies were bound to some catalytic site residues. We conclude from the data obtained in this study that the two different lipase species present close similarities in amino acid sequence and antigen characteristics.     

Surface plasmon resonances, optical properties, and electrical conductivity thermal hystersis of silver nanofibers produced by the electrospinning technique

In the present study, silver metal nanofibers have been successfully prepared by using the electrospinning technique. Silver nanofibers have been produced by electrospinning a sol-gel consisting of poly(vinyl alcohol) and silver nitrate. The dried nanofiber mats have been calcined at 850 degrees C in an argon atmosphere. The produced nanofibers do have distinct plasmon resonance compared with the reported silver nanoparticles. Contrary to the introduced shapes of silver nanoparticles, the nanofibers have a blue-shifted plasmon resonance at 330 nm. Moreover, the optical properties study indicated that the synthesized nanofibers have two band gap energies of 0.75 and 2.34 eV. An investigation of the electrical conductivity behavior of the obtained nanofibers shows thermal hystersis. These privileged physical features greatly widen the applications of the prepared nanofibers in various fields.     

Hydrolytic Heterocyclization of the 1,1,2,3,3‐Pentacyanopropene Salts

Salts of 5‐amino‐4‐cyano‐3‐dicyanomethylene‐2‐pyrrolinone are formed by action of dilute aqueous solutions of alkalis on pentacyanopropenide‐anion salts. These cyclic salts are transformed to 2,6‐diamino‐3,5‐dicyanoisonicotinates by subsequent action of alkalis.     

Information Approach to the Digital Recording of Signals

Radiophysics and Quantum Electronics - In this work, we study the problems of processing complex-nature signals subject to noise, which arise because of the insufficient dynamic range of these...     

Improved antibacterial activity of HAP garlanded PLGA ultrafine fibers incorporated with CuO: synthesis and characterization

Well-organized nanocrystalline hydroxyapatite nanoparticles garlanded poly(dl-lactide-co-glycolide) (PLGA) ultrafine fibers with efficient antibacterial properties are of great interest in the development of new products. In the present study, hydroxyapatite doped PLGA ultrafine fibers incorporated with copper oxide nanocrystals were fabricated via two step methodology. Primarily; copper oxide nanocrystals were synthesized using wet chemical method. Then the as-synthesized nanocrystals were used for the preparation of composite fibers using electrospinning technique. The properties of pure and composite ultrafine fibers were characterized using X-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis, and electron probe mapping analysis. The in vitro antimicrobial activity of synthesized pure and hydroxyapatite doped PLGA ultrafine fibers was investigated against model organism Escherichia coli (gram negative) using optical density method and morphological damage was observed by TEM. Ultrafine fibers with average diameter ranges from 1.0 to 1.2 μm were obtained. Uniform distribution of hydroxyapatite was observed. Admirable antimicrobial activity against E. coli was achieved which could be attributed by the synergy between hydroxyapatite and copper oxide. In contrast to pristine PLGA, lower concentrations of hydroxyapatite–copper oxide doped PLGA nanocomposite were needed to strongly inhibit the growth of E. coli. Our results report successful preparation of hydroxyapatite–copper oxide based novel nanocomposite. The developed hybrid nanocomposite possess exceptionally good antibacterial activity against E. coli due to the synergistic effect of hydroxyapatite and copper oxide. The antimicrobial nanocomposite can be utilized for a range of bio-functional purposes such as a good candidate for water purification, antibiofouling, wound dressings and bone tissue engineering etc.     

Metal-sensitive and thermostable trypsin from the crevalle jack (<Emphasis Type="Italic">Caranx hippos</Emphasis>) pyloric caeca: purification and characterization

Background

Over the past decades, the economic development and world population growth has led to increased for food demand. Increasing the fish production is considered one of the alternatives to meet the increased food demand, but the processing of fish leads to by-products such as skin, bones and viscera, a source of environmental contamination. Fish viscera have been reported as an important source of digestive proteases with interesting characteristics for biotechnological processes. Thus, the aim of this study was to purify and to characterize a trypsin from the processing by-products of crevalle jack (Caranx hippos) fish.

Results

A 27.5 kDa trypsin with N-terminal amino acid sequence IVGGFECTPHVFAYQ was easily purified from the pyloric caeca of the crevalle jack. Its physicochemical and kinetic properties were evaluated using N-α-benzoyl-_DL-arginine-p-nitroanilide (BApNA) as substrate. In addition, the effects of various metal ions and specific protease inhibitors on trypsin activity were determined. Optimum pH and temperature were 8.0 and 50°C, respectively. After incubation at 50°C for 30 min the enzyme lost only 20% of its activity. K _m , k_cat, and k _cat /K _m values using BApNA as substrate were 0.689 mM, 6.9 s^-1, and 10 s^-1 mM^-1, respectively. High inhibition of trypsin activity was observed after incubation with Cd²⁺, Al³⁺, Zn²⁺, Cu²⁺, Pb²⁺, and Hg²⁺ at 1 mM, revealing high sensitivity of the enzyme to metal ions.

Conclusions

Extraction of a thermostable trypsin from by-products of the fishery industry confirms the potential of these materials as an alternative source of these biomolecules. Furthermore, the results suggest that this trypsin-like enzyme presents interesting biotechnological properties for industrial applications.

     

An efficient method for the N-arylation of phenylurea via copper catalyzed amidation

The coupling reaction of phenylurea with different functionalized aryl halides in the presence of air stable CuI,N,N-dimethylethylenediamine as a ligand,and K₃PO₄ as a base gives symmetrical and unsymmetrical diarylureas in relatively high yields.This method is milder than the palladium catalyzed arylation and avoids the use of toxic phosphine ligands.