Harnessing selenocysteine reactivity for oxidative protein folding

Although oxidative folding of disulfide-rich proteins is often sluggish, this process can be significantly enhanced by targeted replacement of cysteines with selenocysteines. In this study, we examined the effects of a selenosulfide and native versus nonnative diselenides on the folding rates and mechanism of bovine pancreatic trypsin inhibitor. Our results show that such sulfur-to-selenium substitutions alter the distribution of key folding intermediates and enhance their rates of interconversion in a context-dependent manner.     

Absorption spectra and aqueous photochemistry of β-hydroxyalkyl nitrates of atmospheric interest

Molar absorption coefficients were measured for select alkyl nitrates and β-hydroxyalkyl nitrates in methanol. The presence of the β-hydroxyl group has a relatively minor effect on the absorption spectrum in the vicinity of the weak n → π* transition, which is responsible for photolysis of organic nitrates in the atmosphere. For both alkyl nitrates and β-hydroxyalkyl nitrates, there is an enhancement in the absorption coefficients in solution compared to the gas-phase values. The effect of the β-hydroxyl group on the spectra was modelled with molecular dynamics simulations using an OM2/GUGA-CI Hamiltonian for ethyl nitrate and β-hydroxyethyl nitrate. The simulation provided a qualitatively correct shape of the low energy tail of the absorption spectrum, which is important for atmospheric photochemistry. The role of direct aqueous photolysis in removal of β-hydroxyalkyl nitrates in cloud and fog water was modelled using a relative rate approach, and shown to be insignificant relative to gas-phase photochemical processes and aqueous OH oxidation under typical atmospheric conditions.     

Dynamic buckling of a simple elastic-plastic model under pulse loading

The dynamic buckling of an elastic-plastic imperfection-sensitive model subjected to rectangular- and triangular-shaped loading pulses is examined to provide some insight into the dynamic buckling behaviour of structures. The loading pulse is expressed as a function of the horizontal displacement, which allows an analytical method to be used for determining the stability domains for both pulses. The estimates obtained are compared with some previously published results on the dynamic elastic-plastic buckling of the same model under a step loading. It transpires that for the pulse loading of models with large imperfections dynamic instability occurs either elastically or plastically depending on the pulse duration, while for a step loading only an elastic instability is possible for the parameters examined.     

CR-structures on three dimensional circle bundles

Oblatum 5-VIII-1991 & 9-III-1992     

Cure meters and their problems

The rate of cure of a rubber mix needs to be known for development and for quality control. This paper discusses the meaning of ‘rate of cure’, the methods of calculating it from cure-meter measurements and some of the problems involved, in particular the rate of attainment of the required temperature in the test piece.     

The structure and configuration of pseudomonic acid C

A new antibiotic, pseudomonic acid C (2a), has been isolated from fermentations of the strain of $\text{Pseudomonas fluorescens}$ which produces the known and structurally similar antibiotics pseudomonic acids A (1a) and B (1c).