SVIBOR - Project code: 1-08-195


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Project code: 1-08-195


Main researcher: MAGNUS, VOLKER (82051)

Type of research: basic
Duration from: 01/01/91. to 12/31/93.

Papers on project (total): 40
Papers on project quoted in Current Contents: 17
Institution name: Institut "Ruđer Bošković", Zagreb (98)
Department/Institute: Department of Organic Chemistry and Biochemistry
Address: Bijenička c. 54
City: 10000 - Zagreb, Croatia
Phone: 385 (01) 4561-111/1202
Fax: 385 (01) 425-647

Summary: Derivatives of the plant hormone (auxin), indole-3-acetic acid (IAA) were prepared. These included ring-halogenated and -alkylated IAAs and amino acid and sugar conjugates of IAA, some of which were labeled with stable isotopes. The compounds were used in structural, biological and biochemical studies. Molecular structures and conformations in solution were investigated by X-ray crystallography, NMR NOE-measurements, and computational methods, in close collaboration with expert colleagues from the Ruđer Bošković Institute and foreign institutions. The results were correlated with biological activity as determined in short-term assays and in plant tissue culture. The structural data were also used in a search for ways of immobilizing IAA as a ligand linked to macromolecular carriers with minimal interference with its auxin properties. Biochemical studies included experiments on the function of indole in IAA biogenesis in normal and transgenic plants carrying modified tryptophan-synthesis genes.

Keywords: Plant hormone, auxin, molecular structure, X-ray diffraction, conformation analysis, biological activity, chemical synthesis, biogenesis, metabolism, conjugation, indole, indole-3-acetic acid, alkylindole-3-acetic acid, haloindole-3-acetic acid.

Research goals: At present, crop plants are manipulated to human needs using massive amounts of agrochemicals. This would not be necessary if the endogenous mechanisms controlling growth and development were known in detail and could be optimally exploited or redirected as needed. That this is possible has recently been shown in tomato plants modified in their capability to make the plant hormone, ethylene: their fruits remain firm and marketable for a much longer time than standard tomatoes. We wish to contribute to a better understanding of plant development by elucidating the physiology, biochemistry and chemistry of another class of plant hormones, the auxins with indole-3-acetic acid (IAA) as the most common representative. During the past five-year period, we have focused on structure-activity relationships. Our structural data were based on X-ray diffraction analysis in crystals, from which the conformation in solution was deduced by recently developed computational methods. This is a large step forward, compared to the previous approach of deriving molecular structure by eye inspection of mechanical (e. g. ball-and-stick) models. The structural data obtained were used in attempts to immobilize IAA at macromolecular carriers in a way that does not impede recognition by auxin-binding proteins. Such carrier-linked IAA should be an ideal affinity sorbent for isolating auxin receptors from plant tissues.


  1. Name of project: JF-813 Immunochemical determination of plant indoleacetic acid
    Name of institution: Yugoslav-United States Joint Fund for Scientific and Technological Cooperation
    City: Washington, D.C., SAD

  2. Name of project: CI1*-CT 91-0891 Conformation and molecular dynamics of biologically active (plant) glycosides (and related compounds)
    Name of institution: Europska unija

  3. Name of project: JF 202 Molecular Tools for Research on the Plant Hormone (Auxin) Indole-3-acetic Acid
    Name of institution: United Stated - Croatian Joint Fund (cordinated by the United States Department of Agriculture)
    City: Washington, D.C., SAD


  1. Name of institution: Sveriges Lantbruksuniversitet, Institutionen for Skoglig Genetik och Vaxtfysiologi
    Type of institution: University/Faculty
    Type of cooperation: Occasional exchange of experts
    City: Umea, Švedska

  2. Name of institution: Division of Nuclear Medicine and Biophysics, Department of Pharmacology, UCLA School of Medicine
    Type of institution: University/Faculty
    Type of cooperation: Occasional exchange of experts
    City: 90024 - Los Angeles, SAD

  3. Name of institution: Department of Horticultural Science, University of Minnesota
    Type of institution: University/Faculty
    Type of cooperation: Occasional exchange of experts
    City: Saint Paul, SAD

  4. Name of institution: United States Department of Agriculture, Agricultural Research Service, Beltsville Agricultural Research Center West
    Type of institution: State institute
    Type of cooperation: Joint project
    City: Beltsville, MD, SAD

  5. Name of institution: Medical Foundation of Buffalo, Inc
    Type of institution: Non-profit
    Type of cooperation: Joint publishing of scientific papers
    City: Buffalo, N.Y., SAD

  6. Name of institution: Department of Crystal and Structural Chemistry, Bijvoet Center for Biomolecular Research, Rijksuniversiteit Utrecht
    Type of institution: University/Faculty
    Type of cooperation: Joint publishing of scientific papers
    City: Utrecht, Nizozemska

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Last update: 10/10/95