Association and dissociation rates for the pyrene-(pyr)-labeled oligoribonucleotide substrate pyrCUCU binding to the L-21 ScaI group I ribozyme are reported as a function of temperature. Combined with thermodynamic parameters for binding of pyrCUCU to rGGAGAA, the results allow calculation of the activation and thermodynamic parameters for docking of pyrCUCU into the catalytic core of the riboz...

Free energy landscapes decisively determine the progress of enzymatically catalyzed reactions. Timeresolved macromolecular crystallography unifies transient-state kinetics with structure determination because both can be determined from the same set of X-ray data. We demonstrate here how barriers of activation can be determined solely from five-dimensional crystallography. Directly linking mole...

The molecular mechanisms for plastic deformation of bone tissue are not well understood. We analysed temperature and strain-rate dependence of the tensile deformation behaviour in fibrolamellar bone, using a technique originally developed for studying plastic deformation in metals. We show that, beyond the elastic regime, bone is highly strain-rate sensitive, with an activation volume of ca 0.6...

The difficulties in interpreting the temperature dependence of protein enzyme reactions are well recognized. Here, the hammerhead ribozyme cleavage was investigated under single-turnover conditions between 0 and 60 degrees C as a model for RNA-catalyzed reactions. Under the adopted conditions, the chemical step appears to be rate-limiting. However, the observed rate of cleavage is affected by p...

The concept of 'fragility' constitutes a central point of the glass transition science serving as the 'universal' metric linking previtreous dynamics of qualitatively distinct systems. Finding the fundamental meaning of fragility is the 'condicio sine qua' for reaching the long expected conceptual breakthrough in this domain. This report shows that fragility is determined by the ratio between t...

research works proposed that radical scavenging activity of flavonoids is due to ring b, andthe remaining part of the molecule can be disregarded. thus the objective of this work is toobserve whether hydroxytoluenes account the radical scavenging activity of flavonoid and toestablish structural requirements for their activity (as they showed appreciable activity) andelucidate a comprehensive me...

Many RNAs need Mg2+to produce stable tertiary structures. Here we describe a simple method to measure the rate and activation parameters of tertiary structure unfolding that exploits this Mg2+dependence. Our approach is based on mixing an RNA solution with excess EDTA in a stopped-flow instrument equipped with an absorbance detector, under conditions of temperature and ionic strength where, aft...

Atomistic thermodynamic calculations are performed in order to examine the energetic% of self-diffusion in GaAs. An energetic assessment of the activation enthalpy of the saddle-point configuration of various modes of vacancy self-diffusion indicates second-nearest-neighbor hopping to be the energetically most favorable mechanism if vacancies are available in equilibrium concentrations. An asse...

Palladium nanoparticles (NPs) stabilized by ImS3-14, a zwitterionic surfactant structurally related to ionic liquids, are revealed here to be good catalysts for the reduction of a large number of substituted aromatic nitro compounds. Our mass spectrometry results are consistent with the formation of amino products in a direct route, where the aromatic nitro compounds are initially reduced to ni...