Structural studies of integrin mediated signaling by NMR and surface chemistry of fluoroalcohols

The thesis consists of two parts. Part I demonstrates the applicability and uniqueness of solution NMR methods for studying protein-protein interactions (PPIs) and receptor signaling mechanism. In part II surface properties of fluoroalcohols are investigated using FTIR technique.; The link between the extracellular matrix (ECM) and cytoskeleton is mediated primarily by integrins, a group of (alpha/beta) heterodimeric transmembrane receptors. Studies on alphaIIbeta3 integrin showed that the formation of a complex between cytoplasmic tails of alpha and beta subunits keeps the integrin in low-affinity state, whereas cellular activators such as talin induce the dissociation of the complex activating the receptor ("inside-out" signaling). We used transferred NOE experiments to show that alpha and beta cytoplasmic domains of the less studied alpha5beta1 and alphavbeta3 integrins also associate in aqueous solution and dissociate upon binding of talin. Thus we established that cytoplasmic unclasping is a general mechanism of integrin activation.; Here, we also solved the 3D structure of an extremely weak protein-protein complex (Kd ∼ 3 x 10-3M) involving adaptor proteins Nck-2 and PINCH, which is crucial for regulating cell morphology as part of the integrin-mediated signaling network. The complex exhibits a remarkably small yet distinct interface between Nck-2/SH3 and PINCH/LIM4 domains. These data provide an atomic view of a functionally important ultra weak complex and explain how it might transiently regulate the cytoskeleton dynamics as part of large multi-component assembly.; Fluorinated alcohols (FAs) were suggested as alternatives for chlorofluorocarbons (CFCs) since they are expected to be chemically more active in the troposphere. Therefore possible degradation mechanisms and interaction of FAs with tropospheric components in the presence of IR and UV/Vis radiation are of great interest. Al2O3 is one of the main components of the atmospheric aerosol particles. In this work the reactions of 2,2-difluoroethanol and 2,2,2-trifluoroethanol with Al2O3 surface were investigated by FTIR in high vacuum. The results indicated that CHF2-CH2-OH decomposed forming a fluorinated surface ethoxide at 250 K, which decomposed further at 400 K with the formation of surface acetate. CF3-CH2-OH decomposed forming an acetate/formate mixture at 450 K. Surface hydroxyl groups participated in the adsorption/decomposition process for both alcohols. Reaction mechanisms are proposed and the role of fluorination for surface reaction outcome is suggested.