Proline hydroxylation by soybean lipoxygenase.

The lipoxygenase-catalyzed hydroxylation of proline was studied in vitro in the presence of linoleic acid. The rate of reaction exhibited dependence on the concentration of proline, linoleic acid and the enzyme. The magnitude of hydroxyproline formed per mg of protein was time-dependent. Nordihydroguaiaretic acid at 0.1 mM concentration completely inhibited this reaction. No proline hydroxylation was detected during peroxidation of linoleic acid by vanadyl(IV). It is suggested that free-radical products of linoleic acid peroxidation may co-oxygenate proline in the presence of lipoxygenase.