Poly(ADP-ribose) is an unusual polymer formed exclusively in the nuclei of eukaryotic cells. It was discovered in the early sixties in the laboratory of Mandel. The work described in this thesis is aimed at providing an insight into the role of poly(ADP-ribose) in wheat embryos germination (Triticum Aestivus L.). It was shown that nuclei isolated from wheat seeds can incorporate [3H] NAD into acid-insoluble material which was subsequently shown to be poly (ADP-ribose) (Whitby & Whish, 1977). Having established the presence of the polymerising enzyme, ADP-ribose transferase, a method was developed for the isolation of ADP-ribosylated proteins in vivo. A frozen isolated nuclei system was established and it was shown that poly (ADP-ribose) glycohydrolase activity was inactivated by freezing at -20°C. Inhibitor studies have also been employed both in vitro and in vivo in an attempt to relate ADP-ribose transferase activity to the rate, and/or the amount, of germination. The aim of these studies was to find a biological role for protein ADP-ribosylation in the wheat embryo. A comparison could then be made with animal systems so that insight might be gained regarding the function of protein ADP-ribosylation.
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