         ! " # $%&’($ )%* +,,---%$%&’($.)%*)/      Full Length Research Paper Purification and characterisation of a plant peroxidase from rocket (Eruca vesicaria sbsp. Sativa) (Mill.) (syn. E. sativa) and effects of some chemicals on peroxidase activity in vitro Hayrunnisa Nadaroglu 1 *, Neslihan Celebi 1 , Nazan Demir 2 and Yasar Demir 2 1 Department of Food Technology, Erzurum Vocational Training School, Ataturk University, 25240 Erzurum, Turkey. 2 Department of Chemistry, Science Faculty, Mugla University, 48000 Mugla, Turkey. Accepted 20 May, 2013 Rocket (Eruca vesicaria sbsp. Sativa) (Mill.) (syn. E. sativa) was grown and used widely in Turkey as a garnish in salads. A peroxidase (POD) from leaves of rocket (Eruca vesicaria sbsp. Sativa) was purified using sequential (NH 4 ) 2 SO 4 precipitation, CM-Sephadex and Sephacryl S-200 chromatographies. A peroxidase (POD) was purified 220.3-fold from the Rocket (E. vesicaria sbsp. Sativa) with an overall yield of 80.79%. The purified enzyme has an optimum pH, 6.0 and its optimum temperature was 40°C. The V max and K M values were determined by Lineweaver-Burk graphics using different substrates. The purification degree and the molecular mass of the enzyme (34 kDa) were determined by SDS-PAGE and gel filtration chromatography. POD enzyme activity was strongly inhibited by Ca 2+ , Mn 2+ , Hg 2 2+ , Zn 2+ and Fe 2+ as metal ions and SDS, EDTA, ascorbic acid, dithioeritritol as chemicals. But, Ni 2+ , Co 2+ , Cu 2+ slightly activated the enzyme. They inhibited in the different range of peroxidase activity. Changes of POD enzyme’s kinetic parameters were most important during chemicals and metal ions metabolism, because they were risk for environmental pollution. Key words: Rocket (Eruca vesicaria sbsp. Sativa), peroxidase (POD), purification, metal ions. INTRODUCTION Peroxidase (POD) (EC 1.11.1.7), an oxidoreductase enzyme catalyzes reactions between compounds which hydrogen atoms tend to give and H 2 O 2 as the receiver of atoms. POD catalyzes the oxidation of the organic and inorganic substrates by using hydrogen peroxide. In addition, POD also catalyzes dehydrogenation reaction of a large number of aromatic compounds such as phenols, hydroquinone and hidrokinonid amines (Pütter and Becker, 1987; Van Huytstee, 1987). Peroxidases examined in different groups according to the arrangement of amino acids and structure as animal peroxidases, plant, fungal and bacterial peroxidases. These species of peroxidase is due to the differences of amino acid sequences (Welinder, 1979). In plants, peroxidase enzyme has vital functions such as hormonal regulation, defense mechanisms, lignin biosynthesis and adjustment of the amount of indole acetic acid during the catch up the fruits and vegetables (Welinder, 1979; Wakamatsu and Takahama, 1993; Agostini et al., 1997; Adams, 1978; Duarte-Vazquez et al., 2001). In the contemporary world, environment pollution is one of the most important problems of the living that as a result, it constitute the extreme penetration growth, rapid urbanization and advanced technology, and it is threaten to the natural 01))*&(/ %,+) 2’%( +(*%3%,%(&,) 4  5%6 