Catalyzes the conversion of (E)-2-methylpropanal oxime (valox) to 2-hydroxy-2-methylpropanenitrile (acetone cyanohydrin) and of (E)-2-methylbutanal oxime (ilox) to 2-hydroxy-2-methylbutyronitrile. The reaction takes place in three steps. First, the oxime is isomerized to the (Z)- isomer, next the (Z)-isomer is dehydrated to the corresponding nitrile, followed by a C-hydroxylation of the nitrile. Can use both aliphatic and aromatic oximes as substrates. (1E,2S)-2-methylbutanal oxime + O2 + reduced [NADPH--hemoprotein reductase] = 2-hydroxy-2-methylbutanenitrile + H(+) + 2 H2O + oxidized [NADPH--hemoprotein reductase] (E)-2-methylpropanal oxime + O2 + reduced [NADPH--hemoprotein reductase] = 2-hydroxy-2-methylpropanenitrile + H(+) + 2 H2O + oxidized [NADPH--hemoprotein reductase] Expressed in storage roots, primary roots, petioles and vascular tissues. Expressed in the outer cortex cells, the endodermis and around the xylem, phloem cells and laticifers. Belongs to the cytochrome P450 family.