Enzymic synthesis of indol-3-ylacetyl-myo-inositol galactoside.
Extracts of immature kernels of Zea mays catalysed the synthesis of indol-3-ylacetyl-myo-inositol galactoside from indol-3-ylacetyl-myo-inositol and UDP-galactose. Addition of 2-mercaptoethanol was required for stability of the catalytic activity during dialysis. The enzyme could be fractionated with (NH4)2SO4, and 55% of the activity was recovered in the 30-60%-saturation fraction. The product of the reaction contained radioactivity from UDP-[U-14C]galactose and was identified as indol-3-ylacetyl-myo-inositol galactoside by gas chromatography-mass spectrometry. Therefore a UDP-galactose:indol-3-ylacetyl-myo-inositol galactosyltransferase (indol-3-ylacetyl-myo-inositol galactoside synthase) is present in developing kernels of Zea mays. The description of this enzyme, together with the enzymes described in the accompanying paper [Michalczuk & Bandurski (1982) Biochem. J. 207, 273-281] for the synthesis of indol-3-ylacetylglucose and indol-3-ylacetyl-myo-inositol, now provides mechanisms for the biosynthesis of one-half of the low-molecular-weight esters of indol-3-ylacetic acid in Zea mays.
D002413:Cations, Divalent / Q000494:pharmacology; D008401:Gas Chromatography-Mass Spectrometry; D005959:Glucosidases / Q000378:metabolism; D007210:Indoleacetic Acids / Q000096:biosynthesis*; D007536:Isomerism; D010944:Plants / Q000201:enzymology*; D003313:Zea mays / Q000201:enzymology
D002413:Cations, Divalent; D007210:Indoleacetic Acids; C037010:indol-3-ylacetylinositol galactoside; D005959:Glucosidases