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KMID : 1160620040090030283
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Preventive Nutrition and Food Science
2004 Volume.9 No. 3 p.283 ~ p.288
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Partial Purification and Characterization of Superoxide Dismutase from Tomato (Lycopersicon esculentum) Fruit
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Kumar Sunil
Dhillon Santosh
Singh Dharam
Singh Randhir
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Abstract
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Superoxide dismutase (SOD) from tomato (Lycopersicon esculentum Mill.) fruit was purified by ammonium sulphate precipitation, Sephadex G-100 and DEAE-cellulose column chromatographies. A 22 fold purification and an overall yield of 44% were achieved. The purified enzyme was a homodimer with Mr 37.1 kDa and subunit Mr 18.2 kDa as judged by SDS-PAGE. SOD showed K_m values of 25×10^(-6) M and 1.7×10^(-6) M for nitroblue tetrazolium (NBT) and riboflavin as substrates, respectively. The enzyme was thermostable upto 50℃ and exhibited pH optima of 7.8. The effect of metal ions and some other compounds on enzyme activity was studied. Co^(2+) and Mg^(2+) were found to enhance relative enzyme activities by 27% and 73%, respectively, while Mn^(2+) inhibited the SOD activity by 64%. However, Ca^(2+) and Cu^(2+) had no effect on enzyme activity. Other compounds like H₂O₂ and NaN₃ inhibited enzymatic activities by 60% and 32%, respectively, while sodium dodecyl sulphate (SDS), chloroform plus ethanol and β-mercaptoethanol had no effect on the activity of SOD.
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KEYWORD
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inhibitors, nitroblue tetrazolium, purification, superoxide dismutase, thermostability, tomato fruit
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