CHARACTERIZATION OF ACIDIC AND BASIC APOPLASTIC PEROXIDASES FROM NEEDLES OF NORWAY SPRUCE (PICEA-ABIES, L, KARSTEN) WITH RESPECT TO LIGNIFYING SUBSTRATES

Acidic and basic peroxidases, termed as POD-A and POD-B, were isolated from the apoplastic space of spruce (Picea abies, L.) needles and pur ified by acetone precipitation and anion exchange chromatography to ap parent homogeneity. The molecular masses of POD-A and POD-B were 39.6 and 29.0 kDa, respectively, The pH optimum of both isozymes ranged fro m 4.5 to 6. The apparent K-m values of POD-A and POD-B were 460 and 21 0 PM for coniferyl alcohol. Both isozymes acted also as NADH oxidases with apparent K-m-values of 103 mu M (POD-A) and 70 mu M (POD-B). NAD( +) but not NADH was found in the apoplastic space of lignifying needle s. Based on the lignification rate, the contents and kinetic propertie s of PODs, NADH oxidation by POD is not the major source of H2O2 requi red for lignin polymerisation.