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Plant Physiology 74:295-301 (1984) © 1984 American Society of Plant Biologists Azido AuxinsQuantitative Binding Data in Maize 1Department of Plant Biology and School of Chemical Sciences, University of Illinois, Urbana, Illinois 61801
The binding constants of three auxin analogs, 4-, 5-, and 6-azidoindole-3-acetic acid (4-, 5-, and 6-N3IAA), and of the photoproducts of 5-N3IAA to the naphthalene-1-acetic acid (NAA) binding sites of Zea mays L. WF9 x BR38 were determined to evaluate the potential of these analogs as photoaffinity labeling agents. We have found that 4- and 5-N3IAA bind to these sites with affinities similar to that of IAA, while 6-N3IAA and the photoproducts of 5-N3IAA bind less tightly. This binding is fully reversible in the dark. Binding of 5-N3IAA becomes covalent and irreversible upon UV irradiation, as evidenced by a 30% loss in NAA binding at sites pretreated with 5-N3IAA and UV irradiation, then washed extensively. IAA or NAA, included with this 5-N3IAA pretreatment, can protect the sites from blockage, whereas benzoic acid and tryptophan are unable to protect the site, indicating that 5-N3IAA specifically labels the auxin sites.
2 Department of Plant Biology. 3 School of Chemical Sciences. 1 Supported by grants from the National Science Foundation (PCM 77-14175 and PCM 80-21632), Hoffman-LaRoche Foundation, and the Graduate Research Board, University of Illinois, and by a Dissertation Grant to A. M. J. Presented, in part, at the 11th International Conference on Plant Growth Substances, Aberystwith, Wales, July 10-16, 1982. This article has been cited by other articles:
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