Please use this identifier to cite or link to this item: http://hdl.handle.net/2440/124109
Type: Thesis
Title: Structural Investigation of Snake Venom Proteins by Mass Spectrometry
Author: Wang, Chia-De Ruth
Issue Date: 2019
School/Discipline: School of Physical Sciences
Abstract: Snake venoms are a rich and complex source of bioactive proteins and peptides. The proteomic variability of snake venoms introduces fascinating and complex investigations from a venom adaptational perspective, and the potency and specificity of these venom proteins lend promising potential for therapeutic applications. However, a significant knowledge gap exists in the proteomic and higher-order structural understanding of venom proteins, which poses a challenge for successful applications. The research in this thesis is focussed on probing ecological and structural biology questions surrounding snake venoms of medical importance from a fundamental protein structural level using mass spectrometry (MS)-based proteomics and native MS. This work contributes towards bridging the knowledge gap between venom protein structure and potential applications, and further expands knowledge of venom diversity. The venom composition of the Australian tiger snake Notechis scutatus was studied using a shotgun proteomics approach from five different geographical populations in response to the polymorphic and widespread geographical diversity exhibited by this species. Analysis of the five venom proteomes established a high degree of diversity in the various toxin groups identified in each population, and in particular, significant variations in relative abundance of 3 finger-toxins appeared to be the greatest distinction across the five venoms. Venom proteomic variations between populations may be due to a diet prey-type influence although climate, seasonal, and intrinsic variabilities must also be considered. Quaternary structures of various venom proteins from a repertoire of medically significant venoms including Collett’s snake Pseudechis colletti, the forest cobra Naja melanoleuca, and the puff adder Bitis arietans were explored for the first time. Using a combined approach of proteomics, native and denatured MS, a 117 kDa non-covalent dimer of a minor toxin component L-amino acid oxidase in the P. colletti venom and a 60 kDa tetramer of a major toxin group C-type lectin in the B. arietans venom were identified amongst other components. A targeted, higher-order structural characterisation of phospholipase A2s (PLA2) in P. colletti venom by combined native and denatured MS analyses revealed a variety of monomeric, highly modified PLA2s. Furthermore, a 27.7 kDa covalently-linked PLA2 dimer was identified in P. colletti venom for the first time by MS, and these PLA2 species were also found to adopt a highly compact and spherical geometry based on ion mobility measurements of collision cross section. Importantly, further exploration of the catalytic efficiencies of the monomeric and dimeric forms of PLA2 using a MS-based PLA2 enzyme assay revealed that dimeric PLA2 possessed substantially greater bioactivity than monomeric PLA2. This highlights the significance of quaternary structures in augmenting biological activity, and emphasises the importance of understanding higher-order protein interactions in venoms.
Advisor: Pukala, Tara
Booker, Grant
Dissertation Note: Thesis (MPhil.) -- University of Adelaide, School of Physical Sciences, 2020
Keywords: snake venom proteins
native mass spectrometry
proteomics
Provenance: This electronic version is made publicly available by the University of Adelaide in accordance with its open access policy for student theses. Copyright in this thesis remains with the author. This thesis may incorporate third party material which has been used by the author pursuant to Fair Dealing exceptions. If you are the owner of any included third party copyright material you wish to be removed from this electronic version, please complete the take down form located at: http://www.adelaide.edu.au/legals
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