A simple method for determining the relative activities of individual peroxidase isozymes in a tissue extract

✍ Scribed by Edwin H. Liu

• Publisher: Elsevier Science
• Year: 1973
• Tongue: English
• Weight: 599 KB
• Volume: 56
• Category: Article
• ISSN: 0003-2697
• DOI: 10.1016/0003-2697(73)90179-6

✦ Synopsis

A peroxidase specific zymogram staining procedure has been designed which not only locates peroxidase isozymes which have been resolved electrophoretically, but. simultaneously estimates the relative activity of each peroxidase isozyme in the system under study. This quantitative assay of individual peroxidase isozymes is chronometric; the time required for the appearance of a peroxidasc band is inversely proportional to its activity. By recording the time required for the appearance of each peroxidase isozyme in a tissue extract, the percent contribution each isozyme makes toward the total peroxidatic activity of that tissue can readily be determined.

Peroxidase (donor:HZOz oxidoreductase; EC 1.11.1.7) is a heme protein commonly found in higher organisms (1). This enzyme is often found in multiple molecular forms (isozymes) which are recognized by their distinct electrophoretic mobilities.

In plants, the peroxidase system shows considerable variation in isozyme patterns. For any given plant the peroxidase isozymes expressed in a zymogram depend both on the tissue used for assay and the developmental stage of the plant at the time of assay. Multiple forms of peroxidase have been found to vary with different organs in maize (2), petunia (3)) peas (4,5), barley ( 6)) and horseradish (7).

Changes in the peroxidase isozyme within a particular organ of a plant can be correlated with the developmental stage of that organ. Such temporal changes have been shown to occur in maize ( 8)) in developing pea cotyledons (5), in bean leaves (9)) and the germinating seeds of wheat (10) and barley (11).