New aspects of the cereal storage protein synthesis and degradation including the role of thioredoxin, as well as its regulatory properties

Abstract

In this review the thioredoxin (TR) contribution to the multiple oxidoreductive processes, such as the transporting of protein in the electron and proton transfer, are presented. Also its cooperation with NADP+/NADPH, ferredoxin (Fd), TR-reductase and protein disulfide isomerase (PDI) are discussed. The main aspect of the review concerns the participation of TR system in the final oxidation of cereal storage proteins in grain maturation, as well as in the reduction of those proteins during grain germination, preceding their proteolysis. Therefore the newer information on the structure of cereal storage proteins and some aspects of their biosynthesis, are also presented.During the study concerning the TR s,~stem the existence of the mechanisms of its regulatory action are also shown. The regulation of enzymes containing SH groups in the active site, as well as those containing such groups in other regions of the molecule belong to them, the change of oxidation degree (by TR) causes in the latter case the conformation conversion, which regulates the catalysis rate. To this latter group some enzymes of photosynthetic Calvin cycle or the pentose phosphate pathway, could be included. The contribution of TR to those or some other mechanisms is also presented.List of abbreviations: DTT -dithiothreitol, ER-endoplasmic reticulum, Fd -feiTedoxin, MDH -malate dehydrogenase, 2-ME -2-mercaptoethanol, p.a. -post anthesis, PDI -protein disulfide isomerase, PPI -peptidyl-prolyl-cis-trans-isomerase, SDS -sodium salt of dodecylsulfate, TR -thioredoxin, TR-R -thioredoxin reductase, Mm -molecular mass.