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Germination an important mechanism in seed physiology begins by imbibition followed by rapid increase
in oxygen uptake and oxidative phosphorylation processes for which high energy cost is a prerequisite.
Mobilization of food storage along with oxidative phosphorylation generates reactive oxygen species
(ROS). Enzymes responsible for ROS scavenging are consequently of particular importance for the
completion of seed germination process. Peroxidases (E.C.1.11.1.7) have been reported to have various
physiological roles such as oxidation of wide range of biomolecules by accumulation of active forms of
oxygen. In present study, Peroxidase was partially purified 1.42 fold from Lycopersicon esculentum Mill
seedlings with 1.3% yield by 70% ammonium sulphate precipitation and dialysis. The substrate specificity
was checked with Pyrogallol (1, 2, 3-trihydroxybenzene), o-dianisidine (4-(4-amino-3-methoxyphenyl)-2
methoxyaniline) and TMB (3, 3’, 5, 5’-Tetramethylbenzidine) substrates. Km and Vmax values with all
the three substrates were calculated from Lineweaver- Burk graphs. Among the substrates tested, highest
specificity constant and rate of reaction was obtained by oxidation of o-dianisidine which is 181800 μM
and 90.9μmoles/min/ml respectively. Optimum pH, optimum temperature, optimum ionic strength, pH
stability, temperature stability conditions determined for o-dianisidine/H2O2 substrate pattern were found
to be 6.0, 50°C, 0.1, 9.0 and 25°C to 50°C respectively.
Keywords- Peroxidase, Lycopersicon esculentum Mill, enzyme partial purification, enzyme
characterization