Abstract
Thioredoxin occurs in all living cells, and regulates the function of various target proteins by way of the dithiol-disulfide exchange reaction. In many organisms, thioredoxin is involved in protection from the oxidative stress. In phototrophs, thioredoxin has essential regulatory roles that link photosynthesis reaction and other reactions in the chloroplasts. In chloroplasts of Arabidopsis thaliana, 10 thioredoxin isoforms were revealed from the genome analysis. These isoforms were supposed to have their own preference for the target proteins. We considered that the selectivity of the target proteins by each of isoforms will be explained in term of affinity between "thioredoxin" and "target". We then measured affinity between thioredoxin and the target using surface-Plasmon-resonance method. Thus interaction between chloroplast thioredoxin isoforms and target proteins, FBPase and PrxQ, were analyzed. We discuss the affinity of target protein to thioredoxin isoforms based on these interaction studies.
