INOSITOL PHOSPHATES IN BARLEY (HORDEUM-VULGARE L) ALEURONE TISSUE ARESTEREOCHEMICALLY SIMILAR TO THE PRODUCTS OF BREAKDOWN OF INSP(6) IN-VITRO BY WHEAT-BRAN PHYTASE

Partisphere SPX HPLC analysis of endogenous inositol phosphates in [H- 3]inositol-labelled barley aleurone tissue revealed a range of isomers , including D- and/or L-Ins3P, D- and/or L-Ins(1,4)P-2, D- and/or L-In s(1,2)P-2, a third unidentified InsP(2), Ins(1,2,3)P-3, D- and/or L-In s(1,2,6)P-3, D-and/or L-Ins(1,2,3,4)P-4, D- and/or L-Ins(1,2,5,6)P-4, Ins(1,3,4,5,6)P-5, D- and/or L-Ins(1,2,3,4,5)P-5, Ins(1,2,3,4,6)P-5, I nsP(6) and a molecule with the chromatographic properties of an inosit ol pyrophosphate. The striking match between the identities of the ste reoisomers, and in some cases enantiomers, detected in vivo and those stereoisomers produced in vitro by the action of wheat-bran phytase on InsP(6) [Cosgrove (1980) Inositol Phosphates: Their Chemistry, Bioche mistry and Physiology, Elsevier, Amsterdam] strongly suggests that mos t of the inositol phosphates identified are products of the breakdown of InsP(6) by endogenous phytase(s) with stereospecificity similar to that of the wheat-bran enzyme(s).