
%0 Journal Article
%A Hull, Mark R. 
%A Long, Stephen P. 
%A Jahnke, Leland S. 
%T Instantaneous and Developmental Effects of Low Temperature on the Catalytic Properties of Antioxidant Enzymes in Two <emph type="2">Zea</emph> Species
%J Functional Plant Biology
%D 1997/06/30
%V 24
%N 3
%P 337-343
%K 
%R https://doi.org/10.1071/PP96041
%U https://www.publish.csiro.au/paper/PP96041 
%X When Zea mays cv. LG11 plants were grown 14&#x02DA;C(close to the lower thermal limit for leaf expansion), three of the five enzymes of the active oxygen scavenging cycle (Halliwell-Asada Pathway) showed changes in total leaf activity compared with growth at 25&#x02DA;C. Two of theseenzymes, ascorbate peroxidase (APX) and glutathione reductase (GTR), were selected for further investigation. The effects of assay temperature on threekinetic parameters (Vmax,Km,Vmax/Km) were determined inextracts from Z. mays and compared with extracts fromits low temperature tolerant relative, Z. diploperennisIltis, Doebley &#38; Guzman. The kinetic power(Vmax/Km) was determinedbecause the Km alone may not be a useful predictor of anenzyme&#8217;s effectiveness in situ. The decrease inthe kinetic power of APX on lowering the temperature to 5&ordm;C was muchsmaller in Z. diploperennis thaninZ. mays. This suggests that theZ. diploperennis APX is better able to removeH2O2 at severely reducedtemperatures than is APX from Z. mays.Z. diploperennis had a twofold greater ascorbate poolthan the chilling-susceptible Z. mays. Only minordifferences were seen in the kinetic properties of GTR and the size of theglutathione pool between the genotypes. 
