Evidence of zein-bound indoleacetic Acid using gas chromatography-selected ion monitoring-mass spectrometry analysis and immunogold labeling.

Commercial zein was base-hydrolyzed and purified extracts were subjected to gas chromatography-selected ion monitoring-mass spectrometry analysis. Indoleacetic acid (IAA) was shown to be released from this storage protein of corn (Zea mays). Isotope dilution using [(13)C(6)]IAA as an internal standard revealed a conservative ratio of 1 mole IAA to 175 moles zein. Immunoelectron micrographs of isolated protein bodies also showed IAA or an IAA-like molecule associated with zein and deposited within these organelles.