4-hydroxyphenylacetonitrile + reduced [NADPH--hemoprotein reductase] + O2 => (S)-4-hydroxymandelonitrile + oxidized [NADPH--hemoprotein reductase] + H2O + H(+)
4-hydroxyphenylacetonitrile + reduced [nadph--hemoprotein reductase] + o2 => (s)-4-hydroxymandelonitrile + oxidized [nadph--hemoprotein reductase] + h2o + h(+)