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Pregled bibliografske jedinice broj: 249929

Structural studies on 5-(n-alkyl)-substituted derivatives of the plant hormone indole-3-acetic acid

Kojić-Prodić, Biserka; Nigović, Biljana; Tomić, Sanja; Ilić, Nebojša; Magnus, Volker; Giba, Zlatko; Konjević, Radomir; Duax, William L.
Structural studies on 5-(n-alkyl)-substituted derivatives of the plant hormone indole-3-acetic acid // Acta Crystallographica, section B, 47 (1991), 1010-1019 (međunarodna recenzija, članak, znanstveni)

Structural studies on 5-(n-alkyl)-substituted derivatives of the plant hormone indole-3-acetic acid

Kojić-Prodić, Biserka ; Nigović, Biljana ; Tomić, Sanja ; Ilić, Nebojša ; Magnus, Volker ; Giba, Zlatko ; Konjević, Radomir ; Duax, William L.

Acta Crystallographica, section B (0108-7681) 47 (1991); 1010-1019

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
Auxin; indole-3-acetic acid; IAA; 5-alkylindole-3-acetic acid; X-ray crystallography; molecular modeling; biological activity; structure-activity correlations

The biological properties of the plant hormone (auxin) indole-3-acetic acid (IAA) and its ring-substituted derivatives have so far been rationalized by a number of contradictory hypotheses based on incomplete structural data deduced mainly by inspection of molecular models. To permit a more detailed insight into structure-activity correlations, we here compare the structures of IAA and 5-(n-alkyl)indole-3-acetic acids (alkyl = methyl, ethyl, propyl, butyl), as revealed by X-ray crystallography and molecular mechanics calculations, and their growth-promoting activity in a standard bioassay, the Avena mesocotyl test. The following molecular properties were identical for the compounds studied: The benzene part of the indole nucleus was slightly distorted around C7, as previously observed for many other indole derivatives (statistical data included). The 5-(n-alkyl) residue was in an extended zigzag conformation with the C_alpha-C_beta bond perpendicular to, and the C_beta-C_gamma bond pointing away from, the aromatic nucleus. Conformational differences were observed with respect to the orientation of the CH_2-carboxyl bond in the crystalline state: perpendicular to the indole ring plane for 5-methylindole-3-acetic acid (as previously found for IAA), and approximately in that plane for the other IAA derivatives studied. Crystal-packing influences appear to be responsible for this effect, as indicated by the results of molecular-mechanics calculations. The potential-energy-minimized conformations in the crystal lattice environment corresponded closely to those observed by X-ray analysis while, for the isolated molecules in the gas phase, perpendicular orientation of the carboxyl group was always predominant. The plant-growth-promoting properties of the compounds studied were not dramatically different. In particular, 5-methyl- and 5-(n-butyl)indole-3-acetic acids showed very similar activity. This indicates that a 5-substituent as bulky as n-butyl, in the orientation detailed above, does not sterically obstruct interaction with the auxin-binding protein(s) involved in the growth response

Izvorni jezik

Znanstvena područja
Kemija, Biologija


Projekt / tema

Institut "Ruđer Bošković", Zagreb

Časopis indeksira:

  • Current Contents Connect (CCC)
  • Web of Science Core Collection (WoSCC)
    • SCI-EXP, SSCI i/ili A&HCI
  • Scopus

Uključenost u ostale bibliografske baze podataka:

  • Biological Abstracts
  • Chemical Abstracts