Dokument: Sedimenting Light Chains: A Biophysical Analysis of Pathological Immunoglobulin Free Light Chains from Patients with Multiple Myeloma
| Titel: | Sedimenting Light Chains: A Biophysical Analysis of Pathological Immunoglobulin Free Light Chains from Patients with Multiple Myeloma | |||||||
| URL für Lesezeichen: | https://docserv.uni-duesseldorf.de/servlets/DocumentServlet?id=74353 | |||||||
| URN (NBN): | urn:nbn:de:hbz:061-20260902-132056-5 | |||||||
| Kollektion: | Dissertationen | |||||||
| Sprache: | Englisch | |||||||
| Dokumententyp: | Wissenschaftliche Abschlussarbeiten » Dissertation | |||||||
| Medientyp: | Text | |||||||
| Autor: | Tucholski, Florian [Autor] | |||||||
| Dateien: |
| |||||||
| Beitragende: | Prof. Dr. Dieter Willbold [Gutachter] Prof. Dr. med. Rainer Haas [Gutachter] | |||||||
| Dewey Dezimal-Klassifikation: | 500 Naturwissenschaften und Mathematik » 570 Biowissenschaften; Biologie | |||||||
| Beschreibung: | Plasma cell disorders such as multiple myeloma and light chain amyloidosis are characterized by the production of monoclonal immunoglobulin free light chains (FLCs), which can contribute to organ injury, most commonly affecting the kidneys. Although the risk of organ involvement increases with rising serum FLC concentrations, patients with comparable FLC levels can present with markedly different patterns and severity of organ damage. This indicates that pathogenicity is determined not only by clonal burden but also by intrinsic, sequence-dependent physicochemical properties of the FLCs and by local tissue microenvironments that influence destabilization and self-association. Pathological FLCs display pronounced molecular heterogeneity and exist as mixtures of monomers, covalent and non-covalent dimers, higher-order oligomers, and fragments, with relative abundances that depend on environmental conditions. Resolving these dynamic distributions under defined conditions is therefore essential for linking molecular behavior to disease-relevant mechanisms.
In this thesis, sedimentation velocity analytical ultracentrifugation (SV-AUC) was employed to quantify FLC species distributions and to monitor their redistribution under controlled destabilizing conditions. Urinary FLCs from nine multiple myeloma patients exhibited substantial molecular heterogeneity and sample-specific responses to disulfide bond destabilization. Reduction induced redistribution of molecular species with variable extent and kinetics. Dimeric species typically declined at early time points without generating stable monomers, resulting instead in transient, aggregation-prone intermediates. In several samples, persisting dimers were observed, suggesting sequence-dependent disulfide protection or additional non-covalent stabilization. Aggregation behavior varied widely among samples and showed no association with clinical parameters, underscoring the multifactorial nature of organ involvement. To relate these findings to structural stability, SV-AUC was complemented by differential scanning fluorimetry and circular dichroism spectroscopy. Disulfide reduction decreased thermal stability as a function of oligomerization and ionic strength. Prolonged reducing conditions were accompanied by gradual changes in secondary-structure and reproducible fragmentation in FLCs of shared genetic origin, which could not be attributed to a single underlying mechanism. To enable mechanistic investigations under defined redox and folding conditions, recombinant expression systems were established. Full-length patient-derived FLCs were produced in Escherichia coli using cytoplasmic inclusion body expression followed by in vitro refolding, as well as periplasmic secretion to promote oxidative folding in vivo. Minor alterations in redox balance markedly affected species distributions, yielding soluble but non-native conformations with altered molecular profiles. To approximate the eukaryotic folding environment more closely, FLCs were additionally expressed in Pichia pastoris. Recombinant FLCs obtained from this system displayed native-like secondary structure and hydrodynamic properties comparable to the patient-derived counterpart, including sedimentation coefficients for monomeric species, with minor differences in dimeric and higher-order oligomeric species. Overall, pathological FLCs behave as redox- and environment-dependent conformational ensembles. Disulfide chemistry and folding context shape species distributions and modulate, under destabilized conditions, both redistribution toward higher-order assemblies and fragmentation of FLCs. By integrating analyses of patient-derived samples with recombinant material, this work provides a biophysical basis for investigating redox-response signatures and species distributions of FLCs in the context of multiple myeloma and other light chain disorders. | |||||||
| Lizenz: |  Dieses Werk ist lizenziert unter einer Creative Commons Namensnennung 4.0 International Lizenz | |||||||
| Fachbereich / Einrichtung: | Mathematisch- Naturwissenschaftliche Fakultät » WE Biologie » Physikalische Biologie | |||||||
| Dokument erstellt am: | 02.09.2026 | |||||||
| Dateien geändert am: | 02.09.2026 | |||||||
| Promotionsantrag am: | 14.04.2026 | |||||||
| Datum der Promotion: | 28.08.2026 |
