ABSTRACT
Biophysical methods have emerged as attractive screening techniques in drug discovery both as primary hit finding methodologies, as in the case of weakly active compounds such as fragments, and as orthogonal methods for hit validation for compounds discovered through conventional biochemical or cellular assays. Here we describe a dual method employing fluorescent thermal shift assay (FTSA), also known as differential scanning fluorimetry (DSF) and surface plasmon resonance (SPR), to interrogate ligands of the kinase p38α as well as several known pan-assay interference compounds (PAINs) such as aggregators, redox cyclers, and fluorescence quenchers. This combinatorial approach allows for independent verification of several biophysical parameters such as KD, kon, koff, ΔG, ΔS, and ΔH, which may further guide chemical development of a ligand series. Affinity values obtained from FTSA curves allow for insight into compound binding compared with reporting shifts in melting temperature. Ligand-p38 interaction data were in good agreement with previous literature. Aggregators and fluorescence quenchers appeared to reduce fluorescence signal in the FTSAs, causing artificially high shifts in Tm values, whereas redox compounds caused either shifts in affinity that did not agree between FTSA and SPR or a depression of FTSA signal.
Subject(s)
Drug Discovery/methods , Fluorometry/methods , Mitogen-Activated Protein Kinase 14/antagonists & inhibitors , Protein Kinase Inhibitors/chemistry , Protein Kinase Inhibitors/pharmacology , Surface Plasmon Resonance/methods , Humans , Ligands , Mitogen-Activated Protein Kinase 14/metabolism , Protein Binding , Small Molecule Libraries/chemistry , Small Molecule Libraries/pharmacologyABSTRACT
A model of subphtalocyanine molecules ordering on Ag(111) is proposed. We have demonstrated that the driving force of the ordering into honeycomb and hexagonal close packed patterns is a balance of intermolecular and subphtalocyanine-Ag interactions which can be generally expressed by a potential with infinite exclusion in a sufficiently large number of nearest coordination spheres of Ag(111) lattice and oscillatingly decaying behavior outside the sphere of exclusion. To cope with computational problems due to large size of the molecules compared to the substrate lattice period, we introduce the rescaling of Ag(111) lattice, and took into account an infinite exclusion of first, second, and third neighbors, attraction-of fourth and fifth, and repulsion-of sixth and seventh. The phase diagram is obtained by the lattice gas model using Monte Carlo simulations. Very strong first order phase transitions, causing the two-phase coexistence, were found between disordered and honeycomb as well as between disordered and hexagonal closed packed phases.
Subject(s)
Bone Density/genetics , Collagen/genetics , Child , Female , Humans , Male , Polymorphism, GeneticABSTRACT
We investigated the relationship between IGF-I, gender, height, weight, body composition and birth size in 260 healthy 7- and 8-year-old children (139 females). All children were born term at Nepean Hospital, Western Sydney. Body composition was measured using dual energy X-ray absorptiometry. IGF-I levels were determined by radioimmunoassay. Girls had higher IGF-I levels than boys (20.2 +/- 6.5 nmol/l compared to 15.9 +/- 6.1 nmol/l, p < 0.001) but there was no correlation between age and IGF-I. IGF-I was positively correlated with height SDS (R(2) = 0.12), weight SDS (R(2) = 0.19), BMI SDS (R(2) = 0.18), total body fat (%) (R(2) = 0.14), and fat-free tissue/cm (R(2) = 0.03). After adjusting for gender and current weight, IGF-I-levels were inversely related to birth size - children with the lowest birth size and heaviest current weight had the highest IGF-I levels. This correlation between birth weight and IGF-I supports the hypothesis that the IGF-I axis is altered in babies who are small for gestational age.
