Margaret I. Tyler
Macquarie University
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Featured researches published by Margaret I. Tyler.
Biochemical and Biophysical Research Communications | 1986
Robert C. Baxter; Janet L. Martin; Margaret I. Tyler; M.E.H. Howden
A growth hormone-dependent binding protein for insulin-like growth factors (IGF-I and IGF-II) has been isolated from human plasma. Analyzed on SDS gels, the preparation contained a major protein band of 53 kDa, and a minor band of 47 kDa. After transfer to nitrocellulose, both species bound iodinated IGF-I, and could be detected using an antibody raised against the purified preparation. In contrast, an IGF binding protein purified from human amniotic fluid bound IGF-I but was not detectable immunologically. The amino acid comparison of the plasma binding protein preparation was different from that reported for amniotic fluid and HEP G2 hepatoma proteins, and the unique amino-terminal sequence, Gly-Ala-Ser-Ser-Ala-Gly-Leu-Gly-Pro-Val-, was different from that of the amniotic fluid and hepatoma proteins. This study indicates that the growth hormone-dependent IGF binding protein of human plasma is structurally and immunologically distinct from other IGF binding proteins.
Biochimica et Biophysica Acta | 1987
Margaret I. Tyler; Donal Barnett; Philip Nicholson; Ian Spence; M.E.H. Howden
Textilotoxin is a presynaptic neurotoxin from the venom of the Australian common brown snake, Pseudonaja textilis. It has the highest lethality and is structurally the most complex of any known snake venom neurotoxin. It was resolved into its five non-covalently linked subunits in a single step by reverse-phase HPLC. Two of the subunits were identical. The N-terminal amino-acid sequence and amino-acid composition of each subunit were determined. Subunit A was the only one found to possess phospholipase A activity. Separation of textilotoxin into its subunits was reversible and reformed textilotoxin had the same Mr and lethality in mice as the native toxin. Experiments with various unnatural combinations of subunits have led to interesting variations in lethality and Mr of the resulting complexes.
Journal of Venomous Animals and Toxins Including Tropical Diseases | 2006
E. J. Vonorax; Margaret I. Tyler; R. K. Atkinson; M.E.H. Howden
Australian funnel-web spiders are relatively large primitive hunting spiders. Male Atrax robustus spiders have been responsible for a number of human deaths. Venom was collected from the species Hadronyche infensa (Hickman) [female], H. formidabilis [male and female], H. versuta [female], and A. robustus (Cambridge) [male] and was fractionated by high performance liquid chromatography. This resulted in the isolation and purification of a homologous series of 7 insecticidal peptides of relatively low molecular mass (approximately 4kDa). The amino acid sequences of these toxins consisted of 36 or 37 amino acids and were named atracotoxins. For the major bioassay of these toxins, we used the cotton bollworm, Helicoverpa armigera (Hubner), due to the great damage it causes to crops worldwide. These toxins, when injected subcutaneously into fifth or sixth instar larvae of Helicoverpa armigera,were lethal or caused an apparently irreversible writhing. The toxin from H. versuta venom showed no significant toxicity when subcutaneously injected into newborn mice. One of the toxins was found to have a free acid carboxyl terminus. These toxins have great potential as lead compounds for insecticide design or for incorporation in recombinant baculovirus insecticides.
Tetrahedron Letters | 1981
Margaret I. Tyler; M.E.H. Howden
Abstract Two fish toxins, linifolin a and linifolin b, which are both diterpene orthoesters, have been isolated from Pimelea linifolia .
Journal of Biosciences | 2009
Alfio Comis; Margaret I. Tyler; Ewan J. Mylecharane; Ian Spence; Merlin Howden
The venom of male Atrax robustus spiders is potentially lethal to primates. These spiders have been responsible for a number of human deaths. Robustoxin is the lethal toxin in the venom. It is a highly cross-linked polypeptide that has 42 amino acid residues and four disulphide bridges. If these bridges are broken, the resulting polypeptide is nontoxic. Robustoxin was chemically synthesized with all of its eight cysteine residues protected with acetamidomethyl groups in order to avoid formation of disulphide bridges. The resulting derivative was co-polymerized with keyhole limpet haemocyanin. Two Macaca fascicularis monkeys were immunized with this conjugate. The monkeys were challenged, under anaesthesia, with a potentially lethal dose of male A. robustus crude venom. Both monkeys showed some minor symptoms of intoxication but recovered fully with no adverse after-effects. Immunization with the same immunogen, in the absence of keyhole limpet haemocyanin, did not protect a third monkey. The N-terminal 23 amino acid peptide derived from the sequence of robustoxin was synthesized and conjugated with ovalbumin. A fourth monkey was immunized with this conjugate. However, it was not protected against challenge. The implications of these results for the preparation of synthetic peptide vaccines are discussed.
Electrophoresis | 1998
Mark P. Molloy; Ben Herbert; Bradley J. Walsh; Margaret I. Tyler; Mathew Traini; Jean-Charles Sanchez; Denis F. Hochstrasser; Keith L. Williams; Andrew A. Gooley
Electrophoresis | 1997
Mark P. Molloy; Shirley Bolis; Ben Herbert; Keli Ou; Margaret I. Tyler; Derek Van Dyk; Mark Willcox; Andrew A. Gooley; Keith L. Williams; Carol Ann Morris; Bradley J. Walsh
Archive | 1993
Alfio Comis; Margaret I. Tyler; Peter Fischer
Journal of Molecular Biology | 1998
Marc R. Wilkins; Elisabeth Gasteiger; Luisa Tonella; Keli Ou; Margaret I. Tyler; Jean-Charles Sanchez; Andrew A. Gooley; Bradley J. Walsh; Amos Marc Bairoch; Ron D. Appel; Keith L. Williams; Denis F. Hochstrasser
Electrophoresis | 1998
Luisa Tonella; Brand J Walsh; Jean-Charles Sanchez; Keli Ou; Marc R. Wilkins; Margaret I. Tyler; Séverine Frutiger; Andrew A. Gooley; Ioana Pescaru; Ron D. Appel; Jun X. Yan; Amos Marc Bairoch; Christine Hoogland; Fabienne S Morch; Graham J. Hughes; Keith L. Williams; Denis F. Hochstrasser