Spatially resolved in situ determination of reaction progress using microfluidic systems and FT-IR spectroscopy as a tool for biocatalytic process development.

A concept for the determination of concentrations in microchannels using FT-IR spectroscopy in transmission is presented. The fundamental idea of spatially resolved measurements along several measuring points was implemented in a single-channel microreactor. Compared to existing microreactor setups for the analysis of fast chemical reactions or mixing processes, the presented concept enables longer residence times at appropriate resolution.

Novel μ-membrane module for online determination of the free fatty acid content in the dispersed phase of oil-in-water emulsions.

Monitoring the dispersed phase of an oil-in-water (O-W) emulsion by means of Fourier transform infrared (FTIR) spectroscopy is a challenging task, restricted to the continuous phase that is in contact with the FTIR probe. Nonetheless, real-time measurement and kinetic analysis by FTIR, including analysis of the dispersed, often non-polar phase containing substrates and/or products, is desirable. Enzymatic hydrolysis of sunflower oil was performed in an O-W emulsion.

Suppression of IAPP fibrillation at anionic lipid membranes via IAPP-derived amyloid inhibitors and insulin.

Aggregation of human islet amyloid polypeptide (hIAPP) into cytotoxic beta-sheet oligomers and amyloid plaques is considered a key event in pancreatic beta-cell degeneration in type 2 diabetes (T2D). hIAPP is synthesized in the pancreatic beta-cells and it is stored, co-processed in the secretory granules, and co-secreted to the extracellular matrix together with insulin. In vivo, hIAPP aggregation may start and proceed at the water-cell membrane interface and anionic lipid membranes strongly enhance the process of hIAPP fibrillization which is causally linked to membrane disintegration and cell degeneration.

Elucidating the mechanism of lipid membrane-induced IAPP fibrillogenesis and its inhibition by the red wine compound resveratrol: a synchrotron X-ray reflectivity study.

The islet amyloid polypeptide (IAPP) or amylin is a pancreatic hormone and crucially involved in the pathogenesis of type-II diabetes mellitus (T2DM). Aggregation and amyloid formation of IAPP is considered as the primary culprit for pancreatic beta-cell loss in T2DM patients. In this study, first X-ray reflectivity (XRR) measurements on IAPP at lipid interfaces have been carried out, providing a molecular level characterization of the first steps of the lipid-induced fibrillation process of IAPP, which is initiated by lipid-induced nucleation, oligomerization, followed by detachment of larger IAPP aggregate structures from the lipid membrane, and terminated by the formation of mature fibrils in the bulk solution.

Amyloidogenic propensities and conformational properties of ProIAPP and IAPP in the presence of lipid bilayer membranes.

Human islet amyloid polypeptide (hIAPP), which is considered the primary culprit for beta-cell loss in type 2 diabetes mellitus patients, is synthesized in beta-cells of the pancreas from its precursor pro-islet amyloid polypeptide (proIAPP), which may be important in early intracellular amyloid formation as well. We compare the amyloidogenic propensities and conformational properties of proIAPP and hIAPP in the presence of negatively charged lipid membranes, which have been discussed as loci of initiation of the fibrillation reaction. Circular dichroism studies verify the initial secondary structures of proIAPP and hIAPP to be predominantly unordered with small amounts of ordered secondary structure elements, and exhibit minor differences between these two peptides only.

Inhibiting islet amyloid polypeptide fibril formation by the red wine compound resveratrol.

GRAPES FOR AMYLOIDS: The red wine compound resveratrol can effectively inhibit the formation of IAPP amyloid that is found in type II diabetes. Our in vitro inhibition results do not depend on the antioxidant activity of resveratrol. Further, the markedly enhanced cell survival in the presence of resveratrol also indicates that the small oligomeric structures that are observed during beta-sheet formation are not toxic and could be off-pathway assembly products.