CHARACTERIZATION OF A DIOXYGENASE FROM TRIGONELLA-FOENUM-GRAECUM INVOLVED IN 4-HYDROXYISOLEUCINE BIOSYNTHESIS

A study was made of the enzyme in fenugreek implicated in the biosynth esis of 4-hydroxyisoleucine which is an unusual amino acid known for i ts insulin stimulating effect. 4-Hydroxyisoleucine was detected by HPL C following isoleucine incubation with a cell-free extract from etiola ted 6-day-old fenugreek seedlings in the presence of various cofactors . The reaction showed that 4-hydroxyisoleucine formation is dependent on the presence of Fe2+, 2-oxoglutarate, ascorbate and oxygen. This su ggests that a 2-oxoacid dependent dioxygenase plays a key role in this biosynthetic pathway. Copyright (C) 1997 Published by Elsevier Scienc e Ltd.