Variations in some extracellular enzyme activities during degradation of lignocellulose byPhanerochaete chrysosporium

The white-rot fungusPhanerochaete chrysosporium is able to degrade lignin only when its primary growth phase is completed. We have recently shown that the organism is able to establish new growth at 10–15 d intervals by recycling its own nitrogen (2). We have now further characterized this growth-rest cycle by measuring changes in extracellular protease, cellulase, and xylanase activities together with total extracellular protein during growth on different carbon sources.

1. WhenP. chrysosporium is grown on a N-limited glucose medium, the cessation of primary growth is closely connected to the increase in extracellular proteolytic activity. When the culture is not O₂-limited (2) it becomes ligninolytically active after about 2 d with a simultaneous decrease in proteolytic activity and an increase in extracellular protein. In O₂-limited cultures, the proteolytic activity remains on a high level for up to 6–7 d. During the second growth phase, the proteolytic activity again increases.
2. When P.chrysosporium is grown on a N-limited glucose medium supplemented with lignocellulosic materials the cellulase and xylanase activities are suppressed and the growth is again connected to an increase in extracellular proteolytic activity. Lignin is not degraded during the growth phases.
3. When P.chrysosporium is grown on a N-limited medium with lignocellulose as the only energy source, the growth phases are connected with increased cellulolytic, xylanolytic, and proteolytic activities. Again during the growth phase, lignin is not degraded. During the ligninolytic phase the level of measured extracellular enzyme activities decreases. A simultaneous increase in total extracellular protein seems to indicate that these enzymes are partly reused for synthesis of the ligninolytic system. Proteins associated with the ligninolytic system appear to be partly reused to synthesize the hydrolytic enzymes for the next growth phase.

     

Elucidation of the structure of drug degradation products by on-line coupled reversed phase HPLC-GC-MS and on-line derivatization

Degradation products obtained under severe alkaline stress of the drug substance ENA 713, a compound developed for the treatment of DAT (dementia of the Alzheimer type), have been identified by on-line coupled reversed phase HPLC-GC-MS as 3-hydroxyaceto-phenone and 3-hydroxystyrene. Their structures were proven by mass spectroscopic investigation of the products obtained by on-column derivatization during LC-GC transfer. On-column trimethyl-silylation and bromination of the degradation products during the transfer were achieved by the introduction of the reagent via the loop-type interface. The usefulness of the technique was further demonstrated by the on-column methylation of carboxylic acids with diazomethane solution (using naproxen as model compound). First results are also given of the use of the liquid-liquid extraction unit of the LC-GC interface for extractive derivatization during reversed phase HPLC-GC-MS transfer.     

On the representation of atoms and molecules as self-interacting field with internal structure

The nonlinear Schrödinger equation with Gaussian convolution kernel K₂ induces the group SU₃ with reference to the classification of the multiplet structure of the eigenstates. Such a field can be used to describe some atoms (where the outermost electrons are related tos-orbitals) as a self-interacting, extended particle with an internal structure. In the case of those atoms, where the valence electrons are described byp-orbitals, and almost all molecules the Gaussian kernel K₂ has to be generalized by Hermite polynomials. By that, we can formulate a nonlinear field theory, establishing the spatial symmetry of a system via basis structure functions. Thus the symmetry represents the most essential starting-point for treating molecules as quasi-particles with an internal structure. It will be shown that there is some connection with the concept of chirality functions and the Ginzburg — Landau theory of super-conductivity. The latter theory indicates that we can consider the nonlinear Schrödinger equation and its generalizations as a classical field theory being associated with phase transitions.     

Solar Urea: Towards a Sustainable Fertilizer Industry

Urea, an agricultural fertilizer, nourishes humanity. The century-old Bosch–Meiser process provides the world's urea. It is multi-step, consumes enormous amounts of non-renewable energy, and has a large CO₂ footprint. Thus, developing an eco-friendly synthesis for urea is a priority. Herein we report a single-step Pd/LTA-3A catalyzed synthesis of urea from CO₂ and NH₃ under ambient conditions powered solely by solar energy. Pd nanoparticles serve the dual function of catalyzing the dissociation of NH₃ and providing the photothermal driving force for urea formation, while the absorption capacity of LTA-3A removes by-product H₂O to shift the equilibrium towards urea production. The solar urea conversion rate from NH₃ and CO₂ is 87 μmol g^?1 h^?1. This advance represents a first step towards the use of solar energy in urea production. It provides insights into green fertilizer production, and inspires the vision of sustainable, modular plants for distributed production of urea on farms.     

Synthesis of the repeating unit of the lipoteichoic acid of Streptococcus pneumoniae

The lipoteichoic acid repeating unit of Streptococcus pneumoniae is a complex pseudopentasaccharide (3). It consists of one ribitol-phosphate, one 2-acetamino-4-amino-2,4,6-trideoxy-galactose, one glucose and two galactosamine residues each differently linked, but both carrying one phosphocholine substituent, at position 6. Suitable building blocks (6–10) for efficient and diastereocontrolled ligations were designed, thus providing, after complete deprotection, the target molecule in high purity. Biological tests revealed that repeating unit 3, lacking the lipid moiety, did not stimulate a pro-inflammatory response in human monocytes (hMNCs).     

Satelliten und derivierte Funktoren. I

Ohne ZusammenfassungDer Verfasser dankt dem Deutschen Akademischen Austauschdienst für die gewährte finanzielle Unterstützung     

Hydrogen and helium films as model systems of wetting

Optical experiments on the wetting properties of liquid ⁴He and molecular hydrogen are reviewed. Hydrogen films on noble metal surfaces serve as model systems for studying triple point wetting, a continuous transition between wetting and non-wetting. By means of optically excited surface plasmons, the adsorbed film thickness for temperatures around, and far below, the bulk melting temperature is measured, and the physical mechanisms responsible for the transition are elucidated. Possible applications for other experiments in pure and applied research are discussed. Thin films and droplets of liquid helium are studied on cesium surfaces, on which there is a first order wetting transition. Our studies concentrate on dynamical observations via surface plasmon microscopy, which provide insight into the morphology of liquid helium droplets spreading at different temperatures. Features corresponding to pinning forces, the prewetting line, and the Kosterlitz-Thouless transition are clearly observed.     

The role of electronic density of states in metallic Lanthanum

Observations of X-ray photoabsorption in metallic Lanthanum in the vicinity of the 3d _5/2-edge are given. Two separated absorption peaks are detected at the quantum energies =830.6eV and =834.0eV. The results are interpreted according to the model given in communication I–IV [1].     

A solution spectrum of the nonlinear Schrödinger equation. II

It was shown in a previous communication that the nonlinear Schrödinger equation exhibits a spectrum of eigenfunctions of the form = _k,A _k (coshkx) ^–k and = _k B _k (coshkx) ^–k–1sinhkx, and the corresponding eigenvalues of the energy are related to a band structure with a characteristic energy gap as a significant feature. In the present paper, it is shown that a further spectrum exists exhibiting the general structure = _k=0 A _k(cosh kx)^–k–1/2and = _k=0 B_k(cosh kx)^–k–3/2sinhkx and yielding also a band structure. An extension of the solution spectrum to a nonlinear Klein-Gordon equation and a nonlinear Dirac equation does not imply essential difficulties, and the corresponding characteristic band structure has to be related to a mass spectrum.