Effects of succinylation on thermal induced amyloid formation in Concanavalin A.
ABSTRACT We have recently shown that upon slight thermal destabilization the legume lectin Concanavalin A may undergo two different aggregation processes, leading, respectively, to amyloid fibrils at high pH and amorphous aggregates at low pH. Here we present an experimental study on the amyloid aggregation of Succinyl Concanavalin A, which is a dimeric active variant of Concanavalin. The results show that, as for the native protein, the fibrillation process appears to be favoured by alkaline pH, far from the isoelectric point of the protein. Moreover, it strongly depends on temperature and requires large conformational changes both at secondary and tertiary structure level. With respect to the native protein, the succinyl derivative forms amyloid fibrils in considerably longer times and with a minor exposure of hydrophobic regions. At physiological conditions, Concanavalin A still displays a sizeable tendency to form amyloid fibril, while the succinyl variant does not. A close correlation was observed between the progress of amyloid formation and a narrowing of the tryptophans fluorescence emission band, indicating a reduction of protein conformational heterogeneity in amyloid fibrils.
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ABSTRACT: Aggregation and glycation processes in proteins have a particular interest in medicine fields and in food technology. Serum albumins are model proteins which are able to self-assembly in aggregates and also sensitive to a non-enzymatic glycation in cases of diabetes. In this work, we firstly reported a study on the glycation and oxidation effects on the structure of bovine serum albumin (BSA). The experimental approach is based on the study of conformational changes of BSA at secondary and tertiary structures by FTIR absorption and fluorescence spectroscopy, respectively. Secondly, we analysed the thermal aggregation process on BSA glycated with different glucose concentrations. Additional information on the aggregation kinetics are obtained by light scattering measurements. The results show that glycation process affects the native structure of BSA. Then, the partial unfolding of the tertiary structure which accompanies the aggregation process is similar both in native and glycated BSA. In particular, the formation of aggregates is progressively inhibited with growing concentration of glucose incubated with BSA. These results bring new insights on how aggregation process is affected by modification of BSA induced by glycation.Biochimica et Biophysica Acta 12/2009; 1804(4):789-98. DOI:10.1016/j.bbapap.2009.12.003 · 4.66 Impact Factor
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ABSTRACT: Excitation of the circularly polarized (CP) aperture-coupled hemispherical dielectric resonator antenna (DRA) using a parasitic patch is studied. The analysis consists of two parts, namely the DRA with a parasitic patch and the microstrip feed line. In this paper, theoretical results on the return loss and radiation field pattern are presentedAntennas and Propagation Society International Symposium, 2001. IEEE; 02/2001
- Skin & Allergy News 05/2007; 2(4):4-4. DOI:10.1016/S1558-0164(07)70197-9