The aim of the work presented in this thesis was to investigate the electropolymerisation of indole and various substituted indole monomers, with the objective of electrosynthesising, characterising and functionalising indole-based conducting polymers for possible use as sensor devices. It was found that on electropolymerisation, all of the substituted indole monomers studied formed asymmetric cyclic trimer species. A mechanism was proposed invoking a 3-3' dimer intermediate to explain the nature of the trimer formed. These trimers were believed to initially form in solution and then deposit on to the electrode surface where they could link to form a polymer film consisting of linked trimer units. The polymer film then facilitated the formation of trimers on the film surface. The electronic nature of the substituents was found to control the reactivity of the trimers, and a correlation was found between the electron withdrawing / donating nature of the substituent and the observed potential of the trimer one electron redox reaction. The lyophilicity of the trimer substituents was found to affect the relative solubility of the trimers which controlled the rate of initial adsorption of trimers on to the electrode surface and the rate of desorption of free trimers from the polymer film. It was discovered that for the electropolymerisation of indoles with highly solubilising substituents, a pre-formed polymer layer could be used to encourage the deposition of trimers on to the film and decrease their desportion rate. This was also used to limit any passivation effects noted for electropolymerisation on platinum. The linking mechanism of all the substituted cyclic trimers studied is believed to be very similar. This was tested by studies carried out on the electropolymerisation of N-methylindole. These studies showed that the major product of the N-methylindole electropolymerisation was a highly soluble cyclic trimer species, in addition there was also an appreciable amount of linear polymer produced from the energetically destabilised sterically hindered 3-3'dimer. The absence of any linking of the N-methylindole trimers suggested that the nitrogen positions in the trimer are involved in the linking reaction observed for all of the other substituted indoles studied.

The following work documents three studies undertaken using solid phase synthesis techniques. Interaction of the zinc metalloprotease, endothelin converting enzyme-1(ECE-1), with its peptidic natural substrate big endothelum-1 has been investigated via an SAR study, using solid phase peptide synthesis (SPPS). Truncated forms of the substrate had been previously reported to inhibit ECE-1, this was confirmed however the big ET-1 analogues were shown to be substrates for the enzyme. A short study of the substrate specificity of ECE-1 was carried out. The synthesis of vast libraries of peptides using combinational synthesis has been used to accelerate the drug discovery process. Purification of these mixtures has not been previously attempted. 17-Tetrabenzo [a,c,g,i]fluoroeneyhethoxycarbonyl (Tbfmcc) developed for use with single peptides of proteins, has been used to achieve facile purification of five peptide libraries synthesised using SP. The methodology was fully optimised for the efficient separation of the desired library members from all impurities by exploiting the affinity of TBfmoc for carbon. A potential small molecule inhibitor of the zinc metalloenzyme, farnesyl transferase (FTase), was designed. The efficient solution phase synthesis of this novel structure is reported its adaptation to solid phase synthesis is described, with the view to using multiple parallel synthesis techniques to synthesise a range of analogous.

No description available.

No description available.

The total synthesis of the 3-polyenoyltetramic acid antibiotic altamycin A has been attempted <i>via</i> a novel method of preparing enantiomerically pure tetramic acids. Thus two target fragments were identified: (a) the tetramic acid and (b) the polyenal fragment. The chirality present in the latter was introduced (enantioselectively) through the catalytic Sharpless epoxidation of an isomerically pure allylic alcohol. This epoxide was then elaborated, using Wittig technology, into the aforementioned polyenal unit. The chiral acid was readily available through reaction of an ester enolate with an oxazolidine-2,5-dione of desired stereochemistry. The coupling of these fragments was studied - several methods being tried then evaluated according to their expediency. This approach to altamycin A is sufficiently flexible to allow the preparation of other members of this interesting class of naturally occurring compounds.

An investigation of the substrate requirements of the interleukin-1β (IL-1β) converting enzyme (ICE) has been carried out. Solid phase peptide synthesis has been used to synthesise sequences from precursor IL-1β, a cowpox inhibitor crmA, and the pro region of ICE. The peptides have been assayed to ascertain their inhibitory properties. In the course of this work an attempt has been made to establish a simple way of introducing β-turns into peptides. This has been carried out by the formation of a disulphide bridged species in which cystine formation was facilitated by the use of the turn-inducing 'ProD.Val' moiety, and by the introduction of an unnatural amino acid, <I>cis</I>-3-aminocyclopentane-1-carboxylic acid (ACPC). The β-turns developed in the ICE work have been introduced into a peptide containing a discontinuous epitope of gp120, and have been found, in this instance, to be interchangeable with one another, and with the γ-turn Cys-Val-Cys.

No description available.

No description available.

Two unique features of FT-ICR mass spectrometry are high mass resolution and mass accuracy. These features have been exploited in a novel approach to the study of metal exchange reactions in metallo-proteins using stable isotope labelling. The system chosen, Zn₄-SmtA, is a cyanobacterial metallothionein (MT) Deconvoluted ESI-FT-ICR spectra for Zn₄-FT-ICR spectra for Zn₄-Smt containing Zn isotopes in natural abundance as well as enriched with 93% ⁶⁷Zn show that the Zn₄ cluster of SmtA, in contrast to the structurally-analogous cluster of mammalian MT, contains a kinetically-inert Zn site, a feature which can be related to its secondary and tertiary structure, and which is of potential importance to its biological function. The main body of this work is a systematic study of the dissociation, via ECD, of doubly protonated peptides, such as luteinising hormone releasing hormone (LHRH), bradykinin and bombesin. The most common fragments reported in the literature occur from cleavage of the N-C₁₂ backbone bond, yielding c’ (N-terminal) and z’ (C-terminal) fragments. One striking observation in the spectra of the peptides studied is the presence of prominent radical c fragments (labelled herein c’) and even-electron z fragments (labelled z’). A study of the correlation between the relative abundance of each of the fragment ions as a function of the amino acid sequence for each of the peptides is shown. These experimental studies have been complemented molecular mechanics modelling, using the Amber force field, to correlate with putative gas-phase structures for these doubly protonated peptides. Here, a hypothesis is put forward that the relative ECD fragmentation pattern is related to the gas-phase structure of the peptide ion <i>prior to</i> electron capture, and in particular that hydrogen bonding of the protonated site to the backbone enhances backbone cleavage at that site (referred to as ‘ECD/structure correlation’). The relative ECD fragmentation pattern for bombesin and four LHRH variants are compared to their modelled gas-phase structures. A detailed study of the LHRH variants with sequence pEHWSYGLRPG-OH {1} and pEHWSYGLRPG-NH₂ {2}, and bombesin {3}, showed good agreement between the relative ECD fragment abundances and predicted Amber structures for {1} and {3}, but not for {2}. This may imply that the postulated model is not a full description of the ECD process.

The 2,4-Dinitrophenyl (DNP) group is a hapten with potential use as a simple, inexpensive non-radioactive labelling group for oligonucleotides. DNP phosphoramidites have been synthesized which allow the attachment of multiple spaced and unspaced DNP groups to oligonucleotides during solid-phase DNA synthesis. Results of Polymerase Chain Reaction and antibody binding experiments are reported. A phosphoramidite to introduce multiple hydroxyl functions into oligonucleotides has been synthesized. Reaction of the multiple hydroxyl functions with single-addition biotin and DNP phosphoramidites during solid-phase synthesis allows the introduction of multiple biotin or DNP labels onto the oligonucleotides in high yield. Two single-addition biotin phosphoramidites have been synthesized incorporating benzoyl protection of the biotin moiety, and different spacer arm lenghts. These were used for the synthesis of biotinylated oligonucleotides during solid-phase synthesis. In an attempt to increase cellular uptake of antisense oligonucleotides Vitamin E, cholesterol and adamantane have been attached to oligonucleotides during solid-phase synthesis. Results of thermal denaturation studies on lipophilic oligonucleotides are reported.