Purification, cloning and characterization of a novel peroxidase isozyme from sweetpotatoes (Ipomoea batatas)

Partial purification and biochemical characterization of peroxidase from rosemary (Rosmarinus officinalis L.) leaves

Background:

In this study, it is aimed to purify POD from leaves of Rosmarinus officinalis L. and determine its some biochemical properties. PODs are a group of oxidoreductase enzymes that catalyze the oxidation of a wide variety of phenolic compounds in the presence of hydrogen peroxide as an electron acceptor.

Materials and Methods:

In this investigation, POD was purified 9.3-fold with a yield of 32.1% from the leaves of Rosemary by ammonium sulfate precipitation and ion-exchange chromatography. The enzyme biochemical properties, including the effect of pH, temperature and ionic strength were investigated with guaiacol as an electron donor. For substrate specificity investigation of the enzyme, Michaelis constant and the maximum velocity of an enzymatic reaction values for substrates guaiacol and 3,3’, 5,5’-TetraMethyle-Benzidine were calculated from the Lineweaver–Burk graphs.

Results:

The POD optimum pH and temperature were 6.0 and 40°C. The POD activity was maximal at 0.3 M of sodium phosphate buffer concentration (pH 6.0). Sodium dodecyl sulphate polyacrylamide gel electrophoresis was performed for molecular weight (M_w) determination and M_w of the enzyme was found to be 33 kDa. To investigate the homogeneity of the POD, native-PAGE was done and a single band was observed.

Conclusion:

The stability against high temperature and extreme pH demonstrated that the enzyme could be a potential POD source for various applications in the medicine, chemical and food industries.

Comparative analysis of peroxidase profiles in Chinese kale (Brassica alboglabra L.): evaluation of leaf growth related isozymes

Plant peroxidases (EC 1.11.1.7) with different isoforms catalyze various reactions in plant growth and development. However, it is difficult to elucidate the function of each isozyme in one plant. Here, we compared profiles of entire isozyme in young seedling and mature leaves of Chinese kale (Brassica alboglabra L.) on zymogram and ion exchange chromatography in order to investigate leaf growth related peroxidase isozymes. The results showed that four isozymes were constitutively expressed in kale leaves, whereas other two isozymes were induced in the mature leaves. The Mono Q ion exchange chromatography separated the six isozymes into two major groups due to the difference in their isoelectric points. The results suggested that although there were several isozymes in the leaves of Chinese kale, one isozyme functioned mainly through the leaf development. Two anionic isozymes with molecular weights lower than 32 kDa were considered mature related.