Comparative ab initio SCF conformational study of 4-chloro-indole-3-acetic acid and indole-3-acetic acid phytohormones (auxins)

✍ Scribed by Michael Ramek; Sanja Tomić; Biserka Kojić-Prodić

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 516 KB
• Volume: 60
• Category: Article
• ISSN: 0020-7608
• DOI: 10.1002/(sici)1097-461x(1996)60:8<1727::aid-qua1>3.0.co;2-#

✦ Synopsis

An ab initio conformational analysis of 4-chloroindole-3-acetic acid was performed at the RHF/6-311G * * level. The mirror symmetrical conformer (in which the indole ring is coplanar with the COOH group) is most stable; next in energy are the two conformers with the C-COOH fragment perpendicular to the indole ring with relative energies of 2.72 and 6.69 kJ/mol. H ... C1 hydrogen bonding results in only a minor stabilization. The results are combined with those obtained earlier for indole-3-acetic acid and recent biological data regarding auxin (growth hormone) activity. From this, assumptions concerning the biologically active conformation are drawn. 0 1996 John Wiley & Sons, Inc. known about its metabolism or its ability to replace IAA. However, in certain plant species of Fabaceae, 4-C1-IAA is more efficient in stimulating cell elongation of grass coleoptiles compared to IAA [4], and both, 4-C1-IAA and 6-C1-IAA are significantly more effective than is IAA in stimulating Avena coleoptile straight growth [51 or pea stem elongation [6, 71. Until now, several auxin-