Inducing structural changes in biological polymers

Glab, Joanna 2009. Inducing structural changes in biological polymers. PhD Thesis, Cardiff University.

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Abstract

The aim of the project is to investigate disorder induced into molecular structure of biological polymers by various extrinsic factors. This study focuses on two major proteins found in the extracellular matrix of connective tissues - collagen and fibrillin. Collagen is the most abundant protein in mammals and can be found in connective tissues providing the all important structural scaffolding for cells. It is mostly found in a highly ordered fibrillar form however, various extrinsic factors can lead to its degradation and transformation into disordered gelatine. During degradation, the ordered structure of collagen is lost triple helical molecules unfold into gelatine, however, it has been proposed that this process may involve different intermediate states depending on the treatment. The aim of this project is to identify and characterize these potential metastable states that occur during collagen transformation. Understanding of the underlying molecular transformations can be beneficial in medicine where gelatinisation of collagen is observed in malignant breast tissues (induced by metalloproteinases) or can be induced by heat during surgical treatment (e.g. laser based) or an intense X-ray beam (i.e. used as a sophisticated treatment of cancer). Investigation of induced alteration in biological tissues and other materials that contain collagen (historical parchment, leather) can also benefit biomaterial production and future designs in implant surgery and pharmacy, e.g. tissue-engineered skin substitutes. The results presented in this thesis proved that the nature of collagen transformations varies depending on the treatment and the main findings, which were previously unobserved include: (1) identification of a novel collagen structure with an 80 nm axial periodicity (recorded during an intensive X-ray irradiation), (2) a novel 20 nm periodic structure (formed during UV irradiation) and (3) changes in collagen fibril diameter and interfibrillar spacing (observed in breast cancer tissues). The second of the studied proteins, fibrillin, is a main component of fibrillin-rich microfibrils and plays a crucial role in providing elasticity to the majority of connective tissues. The study described here was designed to investigate the elastic response of fibrillin-rich microfibrils during controlled tissue extension, and hence the effect of the external factor - mechanical stress. The results gave a further insight into the basis of the elastic properties of fibrillin and have major implications for understanding the functionality and extensibility of fibrillin in connective tissues.

Item Type:	Thesis (PhD)
Status:	Unpublished
Schools:	Optometry and Vision Sciences
Subjects:	R Medicine > RE Ophthalmology
ISBN:	9781303214370
Date of First Compliant Deposit:	30 March 2016
Last Modified:	19 Mar 2016 23:31
URI:	https://orca.cardiff.ac.uk/id/eprint/54821

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