Tim-on Man. / Bibliography: leaves 85-87 / Thesis (M.Phil.) -- Chinese University of Hong Kong, 1983

by Wing-kwong Ip. / Bibliography: leaf 105 / Thesis (M.Phil.)--Chinese University of Hong Kong, 1983

by Chin Wing Chan. / Thesis (M.Ph.)--Chinese University of Hong Kong, 1987. / Bibliography: leaves 86-91.

by Ngai Fei Kwok. / Thesis (M.Ph.)--Chinese University of Hong Kong, 1987. / Bibliography: leaves 57-61.

Li Chun Sing. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1980.

Man-kit Leung. / Bibliography: leaves 48-50 / Thesis (M.Ph.)--Chinese University of Hong Kong, 1986

by Cheung Siu-shing. / Includes bibliographical references / Thesis (M.Ph.)--Chinese University of Hong Kong, 1986

Analog-to-Digital Converters (ADC's) are inherently optimized for linearity in order to produce an accurate digital representation of an analog voltage. The Cyclic ADC's linearity is limited by one of its components, the residue amplifier. The residue amplifier is used to amplify the error between the analog voltage and the digital decision by a gain of two in each cycle of a conversion. In previous designs, this was accomplished by using a compound op-amp with a large open loop gain for linearity, and negative feedback to achieve the gain of two. This thesis explores the use of a resistively loaded differential pair to achieve this gain. The design reduces die size, power usage, and analog complexity. To correct for this inherent non- linearity, a Split ADC concept is employed to enable digital background calibration and a correction algorithm to account for this non- linearity. The Integrated circuit is designed, laid out, and simulated using the Cadence Integrated Circuit Front to Back design suite (ICFB) in the 0.18um Jazz CMOS process.

Ribosomal synthesized and post translational modified peptide natural products have attracted a lot of interest in the past decade. Backbone cyclization of the translated linear peptides is generally catalysed by specific enzymes giving them peptidase resistance, thermodynamic stability and various other physiological activities. These features have made backbone cyclic peptide to become an attractive resource for drug discovery. Here, we described the synthesis of linear peptides containing natural and unnatural residues and its biosynthetic mechanism to generate man-made cyclic peptides. In this thesis we used SPPS to make short and medium linear peptide chains, we purified them using HPLC, and analysed them using MS. We incorporated unnatural residues such as homocysteine, homoserine, aminoalanine, propargyl glycine and the substrates were subjected to different enzymatic reaction such as prenylation, heterocyclization and macrocyclization modification reactions to generate small macrocycles (4-6 residues), prenylated linear peptides, and patellamime analogues. The final products were analysed using LC-MS. In our results, we verified that kawaguchipeptin (kgp) gene cluster is responsible for the production of kawaguchipeptins through heterologous expression of the kgp gene cluster in Escherichia coli. The KgpF prenyltransferase was overexpressed and was shown to prenylate C-3 of Trp residues in both linear and cyclic peptides in vitro. We also found out that PatGmac can macrocyclise short peptides (4-6 residues) to generate small macrocyclic peptides. We also tested the flexibility of OscGmac using unnatural amino acid residues such as pseudoprolines and pipecolic acid that can mimic the heterocyle incorporated as the final residue in the natural product. Our results show that OscGmac recognises pseudoprolines before AYD(G) to process a linear peptide.

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