Browsing by Author "Hsu, Yu-Ting"
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- ItemThe binding of small volatile molecules by bovine [beta]-lactoglobulin : a thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Chemistry at Massey University(Massey University, 2008) Hsu, Yu-TingBovine ß-lactoglobulin (ß-Lg) has been studied extensively but there is no clear identification of its biological function. Hydrophobic molecules have been observed binding into the hydrophobic calyx of ß-Lg. By comparison with other members of lipocalin family, it is probable that ß-Lg plays a role of transport of ligands, as ligands also bind into the central cavity of lipocalins. The structurally similar MUP is a pheromone-binding protein; therefore, it is possible that ß-Lg may also fulfil a similar role. This study has begun to test this hypothesis by investigating the interactions between bovine ß-Lg and several small volatile molecules (2-sec-4,5-dihydrothiazole, 3-methyl-2-butenal, 3-methyl-2-buten-1-ol and phenylacetic acid). The interactions between the volatile molecules and ß-Lg were studied by both two-dimensional NMR spectroscopy and X-ray crystallographic methods. TOCSY spectra were recorded for ß-Lg and the complex between ß-Lg and the ligands. The observed chemical shifts in the HN-Ha region are sensitive to the proximity of ligands, and hence chemical shift changes on ligand binding provide information on possible binding sites. It appears that several amino acids with hydrophobic sidechains are affected by interaction with volatile molecules at pH 2.0. The X-ray crystallographic study at pH 8.5 showed that the potential ligand, 2-sec-4,5-dihydrothiazole, may have decomposed into a linear 2-methyl-butanol. The refined structure (R=0.281, Rfree=0.354 for reflections to 2.6 Å resolution) reveals that the potential ligand may bind to the central cavity in a manner similar to the binding of 12-bromodecanoic acid to ß-Lg.
- ItemBiosensors for fertility and pregnancy in cattle : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Chemistry at Massey University, Palmerston North, New Zealand(Massey University, 2013) Hsu, Yu-TingThis project is focused on progesterone sensing, using both surface plasmon resonance (SPR) and lateral flow immunoassay (LFIA) methods with a new progesterone (P4) sensing material to develop cost effective assays for progesterone sensing in bovine serum and milk samples. P4-PEG-OVA was synthesised, characterised and used for P4 detection. The P4-PEG-OVA sensor surface showed an improvement in surface response compared with two shorter ligand 4TP-P4-OVA and 4TPH-P4-OVA in SPR studies. An analysis method has been developed and modified for bovine serum and milk analyses. The results indicated the P4-PEG-OVA ligand allowed sensitive P4 detection in SPR sensing and allowed bovine P4 cycle profiling. The SPR analysed data was compatible with the ECLIA and ELISA independent analyses and the P4 cycle of each of the three bovine milk samples showed a very similar trend and the extraction level was also consistent. The P4-PEG-OVA ligand was used to develop a LFIA sensor strip, and the inhibition assay for bovine serum and milk analyses established. The results indicated that, after appropriate sample pre-treatment, the bovine estrous cycle profile could be detected. The LFIA method can be a potentially quick, easy and cost effective semi-quantitative P4 analysis for serum and milk samples. A new material, polyhydroxyalkanoate (PHA) granules has been investigated for the possibility of developing a new surface biosensor. From the surface studies, the results indicated that the 3GNZZPhaC beads have the potential to become an alternative binding material for SPR sensing due to its unique gold binding property. A flow cell was designed, constructed, and tested on 3GNZZPhaC beads prior the preliminary SPR investigations. The ZZPhaC beads also showed the gold binding property and ZZPhaC beads were used for SPR studies. The results suggested a possible application for them as a new SPR binding material for antibody detection.