DIFFERENTIAL TEMPERATURE SENSITIVITY OF PEA SUPEROXIDE DISMUTASES

The activity of pea (Pisum sativum L.) Cu/Zn and Mn superoxide dismutase isoforms was evaluated across a range of temperatures from 10 to 45-degrees-C. Maximal activity of the Cu/Zn and Mn superoxide dismutase isoforms was observed at 10-degrees-C. Both cytoplasmic and chloroplast Cu/Zn superoxide dismutases exhibit a reduction in staining intensity with increasing temperatures. Mn superoxide dismutase, however, maintained a relatively constant staining intensity across the range of temperatures evaluated. An unrelated enzyme used as a control, malate dehydrogenase, exhibited the expected increase in staining activity with increasing temperatures. These results describe a unique response of a protection enzyme to temperature.