Donna M. Gibson

Visualization of peroxidase isozymes with eugenol, a noncarcinogenic substrate

Abstract Plant peroxidase isozymes utilize hydrogen peroxide to oxidize redox dyes. Benzidine, the substrate most commonly used for identification of peroxidase isozymes, is a potent carcinogen and has been banned from laboratory use. O -Dianisidine, the other common substrate for peroxidase isozymes, is structurally related to benzidine and is a possible carcinogen. A peroxidase zymogram stain has been developed which uses eugenol, a substrate which is safe to use in the laboratory. Peroxidase isozymes are recognized as bright blue fluorescent bands under ultraviolet light and develop within 1 min after staining. Eugenol may also be used in a quantitative fluorimetric assay of peroxidase activity.

Evaluating Student Learning Outcomes in Counselor Education: Recommendations and Process Considerations

The 2009 Council for Accreditation of Counseling and Related Educational Programs Standards call upon counselor educators to assess student learning outcomes (SLOs) throughout the curricula. This article provides an overview of content and process considerations for identifying SLOs; developing assessments; creating measures; collecting, managing, and reporting data; and making meaning and implementing changes at student- and program levels. A case example is provided.

The inhibition of peroxidase and indole-3-acetic acid oxidase activity by British Anti-Lewisite

Abstract British Anti-Lewisite (BAL) binds to horseradish peroxidase in a manner which results in inhibition of both peroxidatic and oxidative functions of the enzyme. BAL competes with hydrogen peroxide for binding on peroxidase, and the inhibition of peroxidatic activity is irreversible. Solutions of purified horseradish peroxidase and individually resolved peroxidase isozymes show a gradual loss of peroxidatic activity with time when incubated with BAL. In these same treatments, however, the inhibition of indole-3-acetic acid (IAA) oxidase activity is immediate. With increasing amounts of enzyme in the incubation mixture, IAA oxidase activity is not completely inhibited and is observed following a lag period in the assay which shortens with longer incubation times. Peroxidase activity during this same time interval shows a lag period which increases with longer incubation times. Lowering the pH removed the lag period for oxidase activity, but did not change the pattern of peroxidase activity. These results suggest that the sites for the oxidation of indole-3-acetic acid and for peroxidatic activity may not be identical in horseradish peroxidase isozymes.