Production and characterization of fungal expansin-related proteins
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Journal Title
Journal ISSN
Volume Title
Kemian tekniikan korkeakoulu |
Master's thesis
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Author
Date
2024-05-21
Department
Major/Subject
Biotechnology
Mcode
CHEM3022
Degree programme
Master's Programme in Chemical, Biochemical and Materials Engineering
Language
en
Pages
67 + 5
Series
Abstract
Expansins are the proteins initially characterized as inducing extensibility and stress relaxation in plant cell walls in a pH-dependent matter. Originally discovered in plants, alike proteins were later found in microbes as well. Nowadays, the identification of expansin-related proteins is based on structural similarities which usually include two-domain structure. These proteins are also characterized by the non-lytic mechanism of weakening cellulose networks that facilitate plant biomass processing. In this thesis, 5 fungal expansin-related proteins were aimed to be produced and characterized. A trial to produce Swollenin from Trichoderma reesei in two Pichia pastoris strains – KM71H and protease-deficient SMD1168H was also completed. Expansin-like proteins from Cronartium quercuum and Melampsora medusae were produced only in the KM71H strain. For all proteins methanol-induced expression was used and among six productions the largest was held in a 7 L bioreactor. Later, for produced proteins and seven more, previously produced in the research group, the surface charge calculations were done as well as amino acid alignment. Alongside, the zeta-potential of five polysaccharide substrates was analysed in three pH values. Protein surface charge and substrate zeta-potential results were used in the binding data explanation. In the substrates’ characterization, the obvious trend of the zeta-potential decrease in a more alkaline environment was observed. Finally, the impact of pH on substrate zeta-potential and predicted protein surface charge was considered.Description
Supervisor
Master, EmmaThesis advisor
Koitto, TaruKeywords
expansin-like protein, swollenin, loosenin-like, zeta-potential, binding, surface charge
