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Has files: YesSubject: search.filters.subject.340407 Proteins and peptides

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    Identifying the male meiotic functions of the spindle matrix protein Megator : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Biochemistry, School of Fundamental Sciences, Massey University, Palmerston North, New Zealand
    (Massey University, 2022) Bianchi, Daniela
    Male infertility is an emerging global concern and investigating the molecular events accountable for healthy sperm formation is crucial to the design of diagnostic assays and curative therapeutics. The work here proposed provides the first characterisation of the nucleopore protein Megator - the Drosophila homologue of the human Tpr - throughout the meiotic divisions responsible for sperm formation. Megator/Tpr performs highly conserved roles at the nuclear pore complex during interphase. In somatic cells mitosis is also part of the spindle matrix, a structure that surrounds the spindle and promotes accurate chromosome segregation as a crucial component of the spindle assembly checkpoint (SAC). Through genetic crossing, a combination of antibodies and fluorescent protein-expressing cells, Megator was found to localise in the spindle during meiosis I, consistent with forming a matrix. Moreover, Megator depletion by in vivo RNAi led to chromosome segregation defects suggesting loss of spindle assembly checkpoint function, as it has been seen in depleted mitotic cells. Remarkably, Megator was not detectable beyond background levels in meiosis II cells. Protein depletion in these cells induced abnormal chromatin masses and some cells were entirely devoid of nuclei. Examination of other spindle matrix proteins revealed that their distributions were altered by Megator depletion. These data suggest that Megator’s roles in male meiosis are semi-conserved with mitosis
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    The study of natural and unnatural peptides : changing medicinal & structural properties : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Chemistry
    (Massey University, 2021) Patel, Suraj
    Nature creates the foundations of life by linking together small, yet versatile, building blocks. Using this principle it can build information storage-molecules like DNA or functional catalyst like peptides and proteins. With the aid of non-covalent interactions these molecules form elegant 3D structures that allow them to have a range of functions and to complete a variety of tasks. However, the natural synthesis of the molecules are often limited by the biological resources available. As chemists, we have limitless choice in building blocks at our disposal, allowing us to make tweaks until we get the most efficient outcome. The purpose of this study is to see how chemists are able to improve on nature through the use of synthetic chemistry. This was attempted through two strands of research. The first strand tried to improve the efficiency of a naturally occurring peptide, opiorphin, by altering the chemical structure without inhibiting its analgesic potency. While the second project investigated a class of synthetic peptide, known as a foldamer, by using a unnatural amino acid building block. A viable design of a prodrug for opiorphin was proposed, which requires further research but has begun to show some promise. While the synthesis of a peptide was not achieved in the second project, issues seen during the synthesis of a dimer have been highlighted and alternative routes have been proposed. In addition, a novel substitution pattern for a cyclophane product has been reported.
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    The synthesis and chemistry of [2.2]paracyclophane amino acid derivatives : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Chemistry at Massey University, Manawatū, New Zealand
    (Massey University, 2020) Etheridge, Leonie
    Due to the ever-growing requirement for chiral compounds, new conditions for stereoselective synthesis are in constant development. Asymmetric organocatalysis is well-studied, with peptide catalysts popular due to their modular and highlyfunctionalisable nature. One such example of their utility is in the Michael reaction, a well-studied carbon-carbon bond forming reaction. [2.2]Paracyclophane is an aromatic industrial precursor compound with remarkable structural and electronic properties. Its conformational bulk and rigidity make it an attractive target for integration into sterically-hindered unnatural amino acids for incorporation into peptides that may be effective organocatalysts. An updated route to 4-amino-13-[2.2]paracyclophane-carboxylic acid (Pca) was developed and optimised. The synthetic route comprises four steps with an overall yield of 50%. This compares with previous routes which had yields between 7 and 48% for 6 - 7 steps. Peptide coupling conditions for the poorly-reactive Pca were developed with some success; including devising a route for direct synthesis of a glycine residue on Pca’s aniline. Four new Pca-containing peptides were described. The above work sets the stage for development of interesting new planar chiral peptide compounds with diverse chemistry. Three Pca-containing peptides were studied as asymmetric organocatalysts in Michael addition between trans-β-nitrostyrene and hexanal and were compared to proline, a known catalyst for this reaction. These tests were performed to probe the relationship between relative conformation between the carboxylic acid and amine moieties of the catalyst, and the catalyst’s stereoselectivity. The Pca-containing catalysts showed an interesting trend to reversal of the prevailing syn product configuration.