Multiple fluorescences. Different triplets from N-methyl-2-N-phenylamino-6-naphthalenesulfonate and its C-protonated form by laser pulse photolysis

The triplets generated by laser pulse excitation of N-methyl-2-N-phenylamino-6-naphthalenesulfonate (1M) and its C-protonated form, the N-methyl betaine of 6-sulfonato-3β-tetralenone N-phenylimine (2M) are distinct and apparently do not interconvert at 25°C either in dioxane-water or in glycerol, for which single pulses must be used to avoid conversion of 1M to 2M. Some parallel results are reported for the N-hydroxyethyl derivatives (1HEand2HE).     

The development of the DIGE system: 2D fluorescence difference gel analysis technology

Two-dimensional (2D) gel electrophoresis is a powerful technique enabling simultaneous visualization of relatively large portions of the proteome. However, the well documented issues of variation and lack of sensitivity and quantitative capabilities of existing labeling reagents, has limited the use of this technique as a quantitative tool. Two-dimensional difference gel electrophoresis (2D DIGE) builds on this technique by adding a highly accurate quantitative dimension. 2D DIGE enables multiple protein extracts to be separated on the same 2D gel. This is made possible by labeling of each extract using spectrally resolvable, size and charge-matched fluorescent dyes known as CyDye DIGE fluors. 2D DIGE involves use of a reference sample, known as an internal standard, which comprises equal amounts of all biological samples in the experiment. Including the internal standard on each gel in the experiment with the individual biological samples means that the abundance of each protein spot on a gel can be measured relative (i.e. as a ratio) to its corresponding spot in the internal standard present on the same gel. Ettan DIGE is the system of technologies that has been optimized to fully benefit from the advantages provided by 2D DIGE.Cy, CyDye, DeCyder, Ettan, ImageMaster and Typhoon are trademarks of Amersham Biosciences Limited. Amersham and Amersham Biosciences are trademarks of Amersham plc.     

Synthetic anisomycin analogues activating the JNK/SAPK1 and p38/SAPK2 pathways

The synthesis of C(4)H and C(4)Me analogues of the JNK/p38 pathway activator anisomycin, based upon an aldol or Claisen construction of the C(3)-C(4) bond, has been demonstrated. The relative activation of the JNK/SAPK1 and p38/SAPK2 pathways in RAW macrophages by these analogues, and their synthetic precursors, has been assessed using immunoblot assays against phosphorylated c-Jun and MAPKAP-K2. These studies demonstrate that some of the synthetic C(4) analogues are also potent activators of these stress kinase pathways.     

Synthesis of 4-(1-methyl-2-pyrrolidinyl)isoquinoline under physiological conditions : a model for the biosynthesis of 4-pyrrolidinylisoquinoline alkaloids

1,2,3,4-Tetrahydroisoquinoline-3-carboxylic acid was oxidatively decarboxylated with sodium hypochlorite, affording a dihydroisoquinoline which on condensation with N-methyl-Δ¹-pyrrolinium acetate, and subsequent aerial oxidation yielded 4-(1-methyl-2-pyrrolidinyl)isoquinoline.     

1-Aryl-4,6-diamino-1,2-dihydro-s-triazines. Contrasting effects on intestinal helminths,bacteria, and dihydrofolic reductase

The preparation of a variety of novel 1-aryl-4,6-diamino-1,2-dihydro-s-triazines is described. These compounds exhibit an array of contrasting effects on intestinal helminths, bacteria, and dihydrofolic reductase. It is concluded that potent anthelmintic activity among the dihydro-triazines is not dependent solely on the bulky-substituent hypothesis advanced by other investigators, and indeed cannot reliably be predicted on this basis.     

Arylaminopyridinato complexes of zirconium

A range of 2-arylaminopyridines (HL) are synthesised readily from bromopyridines and amines using palladium-catalysed amination. Protonolysis reactions of these proligands with ZrX(4)(X = NMe(2), CH(2)Ph, CH(2)Bu(t)) yield zirconium complexes of the type [ML(n)X(4-n)], several of which have been characterised by X-ray crystallography. Control of metal/ligand stoichiometry and structure is pursued by investigation of the effects on substitution patterns of the pyridine and aryl rings. Some distinct patterns emerged; (i) the 6-methyl position on the pyridine appears to be particularly important with regards to control of stoichiometry, although there are co-ligand effects; (ii) structures of the metal alkyl derivatives [Zr(n)(CH(2)R)(4-n)] are dominated by aromatic pi-pi stacking, even when bulky arene substituents are employed at. This leads to the complexes adopting a C(2v)-symmetric core; (iii) the amides [Zr(2)(NMe(2))(2)] have structures for which aromatic pi-pi stacking is unfeasible, and correspondingly C(2)-symmetric or similar structures are adopted. All the structural data presented is consistent with a trans influence order at zirconium Me(2)N > RCH(2) > py.     

Isolation and properties of a thermostable endoglucanase from a thermophilic mutant strain ofTielavia terrestris

A heat-stable enzyme was isolated from the cellulase complex of a thermophilic strain of the micromyceteThielavia terrestris. The purified enzyme exhibited both endoglucanase and xylanase activities and had a mol mass of 69,000 Daltons and an isoelectric point of 6.4. When the cells were grown at 48°C, the initial activity of the purified enzyme using carboxymethylcellulose as a substrate was 150 nkat/mg and the Michaelis constant was 6.6 g/L. The heat stability of the enzyme was high, losing only 20% of the initial activity after a 6-h incubation at 65 °C. When cultures were grown on microcrystalline cellulose and xylose was added after 48 h of growth, endoglucanase and xylanase activities were more than doubled. Similar increases in these activities were observed by growing the cultures on straw.     

The goodness of ergodic adiabatic invariants

For a slowly time-dependent Hamiltonian system exhibiting chaotic motion that ergodically covers the energy surface, the phase space volume enclosed inside this surface is an adiabatic invariant. In this paper we examine, both numerically and theoretically, how the error in this ergodic adiabatic invariant scales with the slowness of the time variation of the Hamiltonian. It is found that under certain circumstances, the error is diffusive and scales likeT ^–1/2, whereT is the characteristic time over which the Hamiltonian changes. On the other hand, for other cases (where motion in the Hamiltonian has a long-time 1/t tail in a certain correlation function), the error scales like [T ^–1 ln(T)]^1/2. Both of these scalings are verified by numerical experiments. In the situation where invariant tori exist amid chaos, the motion may not be fully ergodic on the entire energy surface. The ergodic adiabatic invariant may still be useful in this case and the circumstances under which this is so are investigated numerically (in particular, the islands have to be small enough).     

Complementary C3-symmetric donor-acceptor components: cocrystal structure and control of mesophase stability

The overlap of pi-complementary planar organic frameworks is used to direct the assembly of extended columns of alternating donor and acceptor units. The electron-rich partner, hexaalkoxytriphenylene, is a familiar mesogen, while the electron-accepting complement is mellitic triimide, a new C(3)-symmetric building block that may be readily alkylated at its periphery without compromising its electron-accepting ability. A cocrystal of examples of the two components demonstrates pi-facial overlap of the complementary aromatic surfaces. Preparation of a series of alkylated derivatives of each component allowed the study of an array of 1:1 stoichiometry mixtures. For the optimum donor-acceptor organized mesophases within this grid, temperature stability ranges of well over 100 degrees C are observed, some of which extend below room temperature. X-ray analysis confirms the formation of hexagonally packed, alternating, donor-acceptor columns within each of the observed mesophases. The dramatic effect on mesophase formation and stability engendered via donor-acceptor organization within discrete columns is discussed in terms of the interplay of forces leading to mesophase formation, and the potential to tune mesophase characteristics via manipulation of these factors.