DIFFERENTIAL EXTRACTION AND VARIATION IN SUBSTRATE SPECIFICITY IN ISOPEROXIDASES OF ANNONA SQUAMOSA L
Mohammed Shariq Iqbal and Brijesh Pandey*
ABSTRACT
The present study was aimed to explore role of pH on extraction of isoforms, activity and substrate preference of
isoperoxidase (EC 1.11.1.7). Variation in pH of extraction buffer from 4.5 to 8.8 has shown considerable variation
in extraction of isoperoxidases. In total 18 isoperoxidases have been visualized through activity staining in native
PAGE. These isoperoxidases also exhibited differential substrate selectivity with o-dianisidine and guaiacol.
Through in gel activity staining with guaiacol, high molecular weight isoforms were found active while with odianisidine,
low molecular weight isoforms were found active (especially in samples extracted at pH 6.8 and 7.0).
Very prominent effect of extraction pH on isoperoxidase was visible at pH 6.8 and 7.0. More than 9 isoforms were
noticed at pH 6.8 while the number reduced to 3 at pH 7.0. Maximum peroxidase activity, with guaiacol as
substrate, was observed with enzyme isolated at pH 6.8 and activity taken at pH 8.8 (0.0322± 0.0070 nanokatal),
while with o- diansidine as substrate, maximum activity was observed with enzyme isolated at pH 4.5 and activity
taken at pH 7.0 (0.9409± 0.1123 nanokatal). Two ways ANNOVA revealed no significant variation between
extraction and activity pH with p- value > 0.05 using guaiacol as substrate. However, Significant variation was
observed in enzymes isolated at different pH with p-value <0.05 with o- dianisidine as substrate. It can be
concluded that in A. squamosa different pH of extraction buffer influence isolation of different isoperoxidases,
their activity and substrate preference as well. It is worth mention here that role the isoforms detected at different
extraction and activity pH with two different substrates would be of immense academic and mechanistic
significance.
Keywords: Annona, assay pH, extraction pH, enzyme, peroxidase.
[Full Text Article]
[Download Certificate]
Impact Factor : 8.181 
