Effect of chemical phosphorylation on solubility of buffalo milk proteins

Buffalo milk proteins (casein, co-precipitate or whey protein concentrate) were phosphorylated with phosphorus oxychloride (POCl₃) at three different pH values (5.0, 7.0 and 9.0). The solubilities of phosphorylated milk proteins were examined over the pH range 3.0–9.0 in water and ionic (0.1 m NaCl or 10–70 mm Ca²⁺) systems. The solubilities of buffalo milk proteins decreased at pH 3.0, while there was an increase in the solubilities of casein and co-precipitate near their isoelectric points upon phosphorylation. Solubilities of these phosphorylated milk proteins were pH dependent in 0.1 m NaCl but there was a decrease in their solubilities with increase in calcium ion concentration. This alteration could be due to the shifting of isoionic points of phosphorylated buffalo milk proteins towards acidic pH.     

Immobilization of mushroom polyphenol oxidase on poly(allyl glycidyl ether-co-ethylene glycol dimethacrylate) macroporous beaded copolymers

Functional, macroporous, beaded copolymers containing epoxy groups were synthesized for immobilization of polyphenol oxidase (PPO) from edible mushroom (Agaricus bisporus). The effect of incorporation of two different sets of monomers such as glycidyl methacrylate (GMA) and allyl glycidyl ether (AGE) and the effect of cross-linking agent ethylene glycol dimethacrylate (EGDM) with varying cross-link densities on binding and expression of mushroom PPO activity were studied. The effect of porogen viz. cyclohexanol and hexanol on PPO immobilization was studied. AGE copolymers with hexanol as a porogen were found to give higher binding and expression of PPO activity than GE polymers. Cross-linking of amino groups of enzyme with 5% glutaraldehyde for 6 h gave a stable binding of PPO on AGE-75(Hex) polymer with storage half-life of approximately 25 days. Under optimum conditions, AGE-75(Hex) polymer gave 70.3% of activity yield while percent retention of PPO activity was found to be 83.5%. Immobilized PPO showed a broader pH, higher temperature and excellent storage stability.     

Enzymatic hydrolysis of lysine diisocyanate based polyurethanes and segmented polyurethane ureas by various proteases

This work studies the enzymatic degradation of polyurethanes (PUs) and segmented polyurethane ureas (SPUUs) derived from lysine diisocyanate (LDI) by various proteases. Thiol proteases, such as papain, bromelain, and ficin, showed high activity on PUs. Protease K and chymotrypsin also hydrolyzed the PUs. For almost all SPUUs, papain showed high activity. For example, LDI/poly(caprolactone) diol (M_w = 1250)/ethylene diamine (2/1/1) was hydrolyzed to 43% under the same conditions. The water-soluble degradation products of a polyurethane, LDI/BD (1/1), and two model compounds treated with papain were studied with NMR and GPC analysis. From the results, it was evident that the pendant methyl ester group in LDI was rapidly hydrolyzed, followed by slow hydrolysis of urethane bonds in the backbone chain.     

海洋真菌Penicillium citrinum MNP12010101代谢产物的分离鉴定和活性研究

对海洋真菌桔青霉Penicillium citrinum MNP12010101的发酵液乙酸乙酯萃取部分进行化学研究,采用硅胶,Sephedax LH-20,ODS柱色谱和制备高效液相色谱进行分离和纯化,经过各种光谱方法鉴定,得到7个化合物,其中化合物Ⅴ为首次从自然界分离得到,其活性也属首次报道,化合物Ⅰ,Ⅱ,Ⅳ均为首次从该菌种中分离得到.在进行活性测定时发现,化合物Ⅰ和Ⅲ有较好的细胞毒性;化合物Ⅲ具有较强的胰蛋白酶抑制活性;化合物Ⅰ,Ⅲ,Ⅴ,Ⅵ表现出较高的DPPH清除率.     

Virtual screening of eighteen million compounds against dengue virus: Combined molecular docking and molecular dynamics simulations study

Dengue virus is a major issue of tropical and sub-tropical regions. Dengue virus has been the cause behind the major alarming epidemics in the history with mass causalities from the decades. Unavailability of on-shelf drugs for the prevention of further proliferation of virus inside the human body results in immense number of deaths each year. This issue necessitates the design of novel anti-dengue drug. The protease enzyme pathway is the critical target for drug design due to its significance in the replication, survival and other cellular activities of dengue virus. Therefore, approximately eighteen million compounds from the ZINC database have been virtually screened against nonstructural protein 3 (NS3). The incremental construction algorithm of Glide docking program has been used with its features high throughput virtual screening (HTVS), standard precision (SP), extra precision (XP) and in combination of Prime module, induced fit docking (IFD) approach has also been applied. Five top-ranked compounds were then selected from the IFD results with better predicted binding energies with the catalytic triad residues (His51, Asp75, and Ser135) that may act as potential inhibitors for the underlying target protease enzyme. The top-ranked compounds ZINC95518765, ZINC44921800, ZINC71917414, ZINC39500661, ZINC36681949 have shown the predicted binding energies of −7.55, −7.36, −8.04, −8.41, −9.18 kcal/mol, respectively, forming binding interactions with three catalytically important amino acids. Top-docking poses of compounds are then used in molecular dynamics (MD) simulations. In computational studies, our proposed compounds confirm promising results against all the four serotypes of dengue virus, strengthening the opportunity of these compounds to work as potential on-shelf drugs against dengue virus. Further experimentation on the proposed compounds can result in development of strong inhibitors.     

Leveling up: Are non-gamers and women disadvantaged in a virtual world classroom?

Today's young gamers are tomorrow's students who expect more immersion from their online learning experiences. Teachers and administrators, however, must ask are some students at a disadvantage in such a class and does gender play a role? We examine the degree to which gaming experience and gender influence sense of presence in a virtual world learning classroom. Feelings of presence are key to involvement in virtual worlds. Participants, 348 undergraduates, interacted within a custom designed virtual world classroom focusing business negotiation skills. Results reveal that while gaming experience gives a slight advantage, lack of previous software ownership and gender do not put learners at a disadvantage. This finding shows that non-gamers and females can equally participate in a virtual world classroom, relieving concerns of adoption.     

Preparation of lung targeting microspheres of gelatin ceftiofur alkali

Gelatin ceftiofur alkali microsphere was prepared to observe its characteristics and evaluate preservation conditions. The glutaraldehyde was increased and the carboxylic methyl chitosan was added to improve the microsphere. The experimental results show microspheres have a better morphology surface and fairly regular structure with 4% glutaraldehyde. The average particle size is 15.84 μm and particle size distribution is narrow which shows a good uniformity. Microsphere size was affected by the stirrer speed, dosing ratio and curing degree. The greater drug loaded is, the better microspheres loading is; but with the increase of drug loading rate, the entrapment efficiency increases first and then decreases. The drug release rate of the microsphere is 24.90% in 0.5 h and 84.90% in 48 h, when CMC-GMs with 4% curing agent is 32.03% in 0.5 h and 88.44% in 48 h. So Gms embedding of ceftiofur alkali are better than CMC-GM. The stability tests show that strong light, high temperature, high humidity have a great influence on the microspheres.     

On a generalised plane strain crack problem for inhomogeneous anisotropic elastic materials

A generalised plane strain crack problem is considered for a class of inhomogeneous anisotropic elastic materials. The problem is reduced to a boundary integral equation involving hypersingular integrals. The boundary integral equation may be solved numerically using standard procedures. Some crack problems for a particular inhomogeneous material are considered in detail and the stress intensity factors are obtained in order to assess the effect of the anisotropy and inhomogeneity on the stress field near the crack tips.     

Silver nanoparticles embedded in modified polyallylamine resin as efficient catalysts for alkyne–azide 1,3-dipolar cycloaddition in water

A silver nanoparticle composite based on modified polyallylamine has been synthesized by a simple chemical route and its catalytic activity has been tested for alkyne–azide cycloaddition reaction. This silver nanocomposite shows an excellent catalytic activity at 80 °C for the synthesis of 1,4-disubstituted 1,2,3-triazole by alkyne–azide cycloaddition. The solid silver nanocomposite catalyst was characterized by transmission electron microscopy, Fourier-transform infrared spectroscopy, X-ray diffractometry and thermogravimetric analysis. The developed catalyst is stable in air, easy to prepare and can be recovered easily and reused ten times without a significant decrease in activity.     

Screening of adhesive lactobacilli with antagonistic activity against Campylobacter jejuni

In the present study, 78 lactic acid bacteria (LAB) strains were screened for the antagonistic activity against Campylobacter jejuni and 15 LAB strains with high bactericidal capacity were selected for further study through the analysis of the inhibition zone of LAB spent culture supernatant on the growth of C. jejuni. Among these strains, four isolates, Lactobacillus plantarum N8, N9, ZL5 and Lactobacillus casei ZL4 exhibited high adhesion ability to HT-29 cells. All the cell free supernatant (CFS) of these four strains contained high concentration of organic acid and their inhibition effects against C. jejuni were pH sensitive. Furthermore, these four strains could strongly antagonize the adhesion and invasion of C. jejuni to HT-29 cells and showed good tolerance to artificial gastric and small intestinal juices. This study suggests that Lactobacillus strains N8, N9, ZL4 and ZL5 could be used as potential probiotics in food applications against C. jejuni infection.