Origin of the Heterogeneity of Peroxidase Isoenzyme Group Gr from Nicotiana tabacum. I. Conformation

Abstract

Summary By several methods of de- and renaturation (treatment with urea, guanidine and mercaptoethanol, freezing-thawing, heating-cooling etc.) it was studied whether the multiple molecular forms of tobacco peroxidases, group GI, are conformers or not. Most of the applied methods resulted in inactivation of the enzymes only, or did not show any effect. Only heating-cooling resulted in distinct denaturation-renaturation curves but there was no change in isoenzyme pattern at all. Also treatment of GI-isoenzymes with ion-exchange resins or glycosidases did not influence the molecules in any way. Therefore it was concluded that GI-isoenzymes are not conformational variants of a single polypeptide chain and that the origin of heterogeneity might be -due to different primary structures of the isoenzymes.