Isolation of Indole-3-Acetyl Amino Acids using Polyvinylpolypyrrolidone Chromatography

Amino acid conjugates of IAA can be chromatographed on polyvinylpolypyrrolidone (PVPP) using either acidic methanol or aqueous buffers as eluents. In the aqueous system, elution of the compounds is pH-dependent, and the pattern obtained suggests that hydrophobic interactions contribute substantially to the chromatographic behavior of IAA peptides on PVPP. Purification of soybean seed extracts by PVPP chromatography produced fractions containing indole-3-acetylaspartate and indole-3-acetylglutamate, based on chromatographic and mass spectral analysis, as well as three other indolic compounds, tentatively identified as N-acyl tryptophan derivatives. PVPP chromatography provides an effective preliminary purification of IAA peptides from plant extracts prior to their separation by other techniques such as high performance liquid chromatography.