Amyloid protein aggregates of beta-lactoglobulin and their behavior along the process chain

点击翻译按钮获取中文摘要

Amyloid aggregates occur ubiquitously in nature and are characterized by a stacked β-sheet conformation. Amyloid aggregates from whey protein β-lactoglobulin (BLG) can be specifically produced in order to take advantage of their altered physicochemical properties as a functional substance. The main influencing factors are denaturing conditions induced by high temperatures, interfaces and/or high pressure. At the same time, high stress (shearing, high pressure) and decreasing aW values (drying) also lead to fragmentation of the aggregate. Thus, amyloid aggregates in biotechnological processes can grow unintentionally and lead to unwanted deposits. On the other hand, functional amyloid aggregates can be degraded uncontrollably during processing, whereby their size profile and thus functionality is subject to a certain uncertainty. For process control it is therefore necessary to understand the stability and aggregation behaviour of amyloid BLG aggregates as well as the constructive and destructive forces acting on amyloid structures in biotechnological processes. Based on BLG's self-association process in a homogeneous solution, simplified models will be used to simulate the process from dissolving the BLG to drying. Different morphologies of amyloid aggregates from BLG (fibrils, worm-like, spherical) will be investigated to gain an understanding of their composition, formation and stability. A particular focus is the analysis of the effects of physical and chemical modifications that are relevant in the process chain (e.g. modified interfaces and shear as well as the influence of protein oxidation). The significance of individual amino acid sequences for self-association is to be understood experimentally through targeted mutations of amyloidogenic segments and structure-stabilizing disulphide bridges of BLG. Experimental results will be coupled with numerical simulation in order to gain mechanistical insights. Another focus is the investigation of destabilizing and stabilizing forces during drying and film formation of different amyloid aggregates. In particular, modified interfaces (ice/air), pH changes and concentration of remaining salts are considered relevant. Therefore, the influence on the drying and film formation by various drying processes shall be analyzed. Variances in drying speed and stabilizing additives (cryopreservatives, plasticizers) are relevant parameters that influence amyloid structures from the mesoscale (amyloid aggregate) to the macroscale range (alignment of the amyloid aggregates in the film).