Versatile fluorescence labeling method using activated esters on solid support.

A versatile fluorescence labeling method employing support bound nitrophenyl, N-hydroxysuccinimidyl, 1-hydroxybenzotriazoyl and oxime active esters is described. The relative kinetic properties of different esters were systematically compared using an environment-independent benzoquinoline dye.     

Oxime bond formation for the covalent attachment of oligonucleotides on glass support

The chemical attachment of oligonucleotides on glass slides has been achieved using oxime bond formation. This method has been shown very efficient by comparison with the attachment of amino-oligonucleotides via reductive amination.     

Versatile solid supports for oligonucleotide synthesis that incorporate urea bridge

The universal solid support, USIII, representing a new and improved version of commercial USII, as well as 2 '-deoxynucleoside and 2 '-deoxy-2 '-fluoronucleoside bound supports, incorporating a labile phenoxyacetyl fragment, was synthesized by an aminomethyl polystyrene carbamoylation with corresponding azides in the presence of aqueous triethylammonium bicarbonate. All three solid phases incorporate a stable urea tether, thus bridging the polymer and functional linker. These new matrices proved to be potent solid phases for the synthesis of DNA, RNA, or modified oligonucleotides as well as randomized mixed 2 '-ribo/2 '-deoxy-2 '-fluoro-RNA libraries and/or DNA libraries, randomized with trinucleotides (codons).     

Optimum conditions for growth of cyanobacteria on solid media

The colony forming ability of single cells or very short filaments of 7 strains of cyanobacteria was tested on media solidified by agar or by agar substitutes (Gel Gro or Gel Rite). In addition, the effect of various methods for preparation of agar media on colony forming ability was measured. High efficiency colony formation for most of the strains required that the agar be autoclaved separately from the salts in the medium. The addition of thiosulfate, but not buffer, significantly increased the plating efficiency of most strains.     

Optimization of covalent immobilization of pectinase on sodium alginate support

Pectinase was immobilized on a sodium alginate support using glutaraldehyde and retained 66% activity. The optimal pH for activity shifted from 3.0 to 3.5 after immobilization; however, the optimum temperature remained unchanged at 40°C. The immobilized enzyme also had a higher thermal stability and reusability than the free enzyme, and retained 80% of initial activity after 11 batch reactions.     

Diazo coupling method for covalent attachment of proteins to solid substrates

We describe a process for covalently linking proteins to glass microscope slides and microbeads in a manner that optimizes the reactivity of the immobilized proteins and that is suitable for high-throughput microarray and flow cytometry analysis. The method involves the diazo coupling of proteins onto activated self-assembled monolayers formed from p-aminophenyl trimethoxysilane. Proteins immobilized by this method maintained bioactivity and produced enhanced levels of protein-protein interaction, low background fluorescence, and high selectivity. The binding of immobilized proteins to their specific binding partner was analyzed quantitatively and successfully correlated with solution concentrations. Diazotized surfaces bound more efficiently to proteins containing a hexahistidine tag than those without a his-tag. Moreover, significantly higher reactivity of the immobilized his-tagged proteins was observed on diazotized surfaces than on amine-terminated surfaces. Results suggest that his-tagged proteins are immobilized by reaction of the his-tag with the diazotized surface, thus offering the possibility for preferential orientation of covalently bound proteins.     

GPU-accelerated molecular dynamics simulation of solid covalent crystals

Graphics processing unit (GPU) is becoming a powerful computational tool in science and engineering. In this paper, different from previous molecular dynamics (MD) simulation with pair potentials and many-body potentials, two MD simulation algorithms implemented on a single GPU are presented to describe a special category of many-body potentials – bond order potentials used frequently in solid covalent materials, such as the Tersoff potentials for silicon crystals. The simulation results reveal that the performance of GPU implementations is apparently superior to their CPU counterpart. Furthermore, the proposed algorithms are generalised, transferable and scalable, and can be extended to the simulations with general many-body interactions such as Stillinger–Weber potential and so on.     

Evidence for covalent bonding of native hapten-protein complexes to smooth lipopolysaccharide of Brucella abortus

Abstract Smooth lipopolysaccharide (S-LPS) of Brucella abortus was dissociated from noncovalently attached components by differential centrifugation and exhaustive treatment with guanidinium thiocyanate. Mild alkaline hydrolysis then released ester-linked fatty acids as well as native hapten (NH)-protein complexes. These complexes, comprising 15 to 20% by weight of the S-LPS, failed to dissociate in guanidinium thiocyanate or in boiling SDS, suggesting covalent attachment. Analyses for 2-keto-3-deoxyoctonate demonstrated that the released carbohydrate was NH, rather than degraded O -polysaccharide or intact S-LPS monomers. This provides strong evidence that NH-protein complexes are covalently linked to S-LPS, most likely through ester bonds.     

Growth of yeast colonies on solid media

Colonies on nutrient agar of the aerobic yeast Candida utilis show linear increases in diameter and height with time throughout most of the growth cycle. The concentration of glucose in the agar has a negligible effect on radial growth rate although an increase in the glucose concentration prolongs the linear radial growth phase. The rate of increase in height of the colony is proportional to the square root of the initial glucose concentration. A new model that considers both glucose diffusion and oxygen diffusion in the colony is consistent with the observed colony profiles.     

Alginate-based solid media for plant tissue culture

Summary A new method for solid medium plant tissue culture based on in situ gelation of alginate is proposed as an alternative to agar-based media. In situ gelation by the use of dispersed CaCO₃ and the slowly hydrolysing acid glucono--lactone (GDL) was the basis for the use of alginate as a gelling agent. Inexpensive alginate-based media can be made in a wide range of pH values. Biological tests of these gels, concerning sterile seed growth and microcalli plating of Brassica napus (cv. Topas) and biomass production of Panax ginseng callus, showed results equal to those achieved with agar-based gels.     

易致污染的支原体在固体培养基上的形态特征

目的研究不同条件下、不同生长期易致污染的支原体在固体培养基中的形态特征。方法通过改变支原体菌体浓度、培养时间及培养基组成,观察支原体在固体培养基中的形态变化。结果支原体菌体浓度小于103cfu/m L时,培养至2~3天后可在固体培养基中形成典型的"油煎蛋"状形态,以蔗糖作为碳源培养支原体会导致葡萄糖发酵型支原体(肺炎支原体)不能在固体培养基中形成典型菌落,当使用牛血清代替马血清为支原体提供外源胆固醇时,猪鼻支原体在固体培养基中不能形成典型菌落。结论支原体的不同生长期、菌体浓度、培养基的组成都会使易致污染的支原体在固体培养基上的形态发生变化。     

Traceless synthesis of benzimidazoles on solid support

Traceless solid-phase syntheses of benzimidazoles and 5-(benzimidazol-2-yl)benzimidazoles on 2-(4-formyl-3-methoxyphenoxy)ethyl polystyrene are described. No auxiliary functional groups are left in the products after ultimate cleavage and cyclization.     

Preparation and characterization of UV-curable polymeric support for covalent immobilization of xylanase enzyme

The hydroxyl group of poly(ethylene glycol) monoacrylate (PEGMA) was activated by 1,1′-carbonyldiimidazole (CDI) and then a xylanase enzyme was immobilized to amine active PEGMA. UV-curable polymeric support formulation was prepared by mixing the xylanase bonded PEGMA, aliphatic polyester, 2-hydroxyethyl methacrylate (HEMA), poly(ethylene glycol) diacrylate (PEGDA) and photoinitiator. After UV irradiation, the enzymatic activity of the polymeric matrix was evaluated and compared with the corresponding free enzyme. By immobilization, the temperature resistance of the enzyme was improved and showed maximum activity at 60 °C. pH dependent activities of the free and immobilized enzymes were also investigated, and it was found that the pH of maximum activity for the free enzyme was 6.0, while for the optimal pH of the immobilized enzyme was 6.5. The immobilized enzyme retained 75% of its activity after 33 runs. The morphology of the polymeric support was characterized by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) coupled with SEM was used to explore the chemical composition. The results have confirmed the evidence of enzyme in the structure of the polymeric material.     

Self-protecting bactericidal titanium alloy surface formed by covalent bonding of daptomycin bisphosphonates

Infections are a devastating complication of titanium alloy orthopedic implants. Current therapy includes antibiotic-impregnated bone cement and antibiotic-containing coatings. We hypothesized that daptomycin, a Gram-positive peptide antibiotic, could prevent bacterial colonization on titanium alloy surfaces if covalently bonded via a flexible, hydrophilic spacer. We designed and synthesized a series of daptomycin conjugates for bonding to the surface of 1.0 cm2 Ti6Al4V foils through bisphosphonate groups, reaching a maximum yield of 180 pmol/cm2. Daptomycin-bonded foils killed 53 ± 5% of a high challenge dose of 3 × 10? cfu Staphylococcus aureus ATCC 29213.