Effect of Trichoderma reesei Proteinases on the Affinity of an Inorganic-Binding Peptide

An inorganic-binding peptide sequence with high affinity to silica-containing materials was fused to a glycoside hydrolase GH26 mannanase, ManA, from the extremely thermophilic bacterium Dictyoglomus thermophilum. The resulting recombinant enzyme produced in Escherichia coli, ManA-Linker, displayed high binding affinity towards synthetic zeolite while retaining its catalytic activity at 80 °C. ManA-Linker was able to bind to the zeolite at different pH levels, indicating a true pH-independent binding. However, complete degradation of the peptide linker was observed when the recombinant ManA-Linker was exposed to the supernatant from the filamentous fungus Trichoderma reesei. This degradation was caused by extracellular proteinases produced by T. reesei during its growth phase. Several derivatives of ManA-Linker were designed and expressed in E. coli. All the derivatives carrying a single sequence of the linker were still susceptible to T. reesei proteinase degradation. Complete substitution of the linker sequence by (GGGGS)₁₆ resulted in a proteinase-resistant ManA derivative, ManA-Linker-(GGGGS)₁₆, which was able to bind to zeolite in a pH-dependent manner.     

Molecular dynamics simulations of discotic liquid crystals using a hybrid Gay-Berne Luckhurst-Romano potential

We report the results of the computer simulation of a collection of particles interacting via an anisotropic potential proposed by Luckhurst and Romano and modified by scaling with part of the anisotropic well depth formalism employed by Gay-Berne. Using the molecular dynamics technique for 256 particles in the NVE ensemble, the system is shown to exhibit a variety of mesophases, as the temperature is lowered, and these are provisionally identified as isotropic, discotic nematic, a highly ordered fluid phase with some columnar features and a crystal.     

Electron crystallization

The arguments leading to the concept of an electron crystal in the low density regime of ‘jellium’ are reviewed. Ground-state properties discussed include estimates of the critical density at which the transition to a crystalline state takes place, and then in the low density regime the dielectric function, pair function and momentum distribution are dealt with. The magnetic character of the ground state as a function of density is also considered.

The low-lying excitations of the Wigner electron crystal are phonon-like and hence the low temperature specific heat obeys a T ³ law. Defect models are considered in order to throw further light on the character of excited states.

Finally experimental conditions favourable for electron crystallization are briefly considered.     

Photopyroelectric detection of phase transitions in solids

The recently developed photopyroelectric spectroscopy (P²ES) has been used to investigate phase transitions in solids. In our variable temperature experiments, specific heat curves for Rochelle Salt and V₂O₄ powders were obtained and found in good agreement with results obtained previously via more experimentally involved methods.     

Variable temperature57Fe Mössbauer studies on polymers of vinylferrocene and 1, 1′-divinylferrocene

Variable temperature⁵⁷Fe Mössbauer spectra have been recorded in the range 80–300 K for a number of low molecular weight amorphous polymers containing ferrocene units. These include samples of polyvinylferrocene, polydivinylferrocene by anionic initiation and polydivinylferrocene by cationic initiation. A similar non-linear temperature dependence of InA was observed for all the polymers, although they contain ferrocene units in different structural arrangements. A Debye model was extended to include intramolecular vibrations, and a fit to the experimental data was obtained. However, the model did not yield satisfactory fitting parameters. The observed behaviour of the experimental data could be accounted for by assuming that each macromolecule vibrates within an anharmonic potential.     

佛山市顺德区幼儿头发中六种元素含量水平的研究

测定了佛山市顺德区1100名1～7岁学龄前儿童头发中6种元素含量。结果表明,该区幼儿头发中的Zn为(85.25+20.12)×10~(-6);Fe为(30.13±5.30)×10~(-6),Cu为(9.08±2.35)×10~(-6),Ca为(520.70±98.62)×10~6,Mn为(1.87±0.89)×10~(-6),Pb为(11.79±6.85)×10~(-6),并与周边地区作了比较。