Flavanone oxidase

Fig. 314. Formation of the most important groups of flavonoids 1 Chalcone synthase 2 chalcone isomerase 3 flavanone oxidase...

Other experiments with Gibberellafujikuro] the fungus that produces gibberellin, indicate that GA3 production is blocked by BAS 111. Very detailed and careful experiments conducted with enzymes in cell-free systems strongly support this mode of action, ie, using ent-kaurene oxidase and cinnamate 4-mono-oxygenase isolated from pea apices and soybean suspension cells, and flavanone-2-hydroxylase and dihydroxypterocarpane 6-hydroxylase from soybean suspension cells (31). 

The amino acid sequence predicted from pTOM13 shows a significant similarity to flavanone-3-hydroxylase, which requires Fe and 2-oxoglutarate [96]. Ververidis and John [98] applied the conditions to stabilise flavanone-3-hydroxylase to extract EFE from melon fruits and found that authentic EFE activity was recovered in a soluble fraction in the presence of Fe and ascorbate. This finding allowed other researchers to extract authentic EFE from apple [100,136,137] and avocado [99]. The molecular size of extracted ACC oxidase was about 35 kDa in both SDS-PAGE and gel filtration. This result indicates that ACC oxidase is a monomeric enzyme, and isolated cDNA clones represented by pTOM13 encode the entire ACC oxidase. 

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