Was improvement of spinach growth by nano-TiO2 treatment related to the changes of Rubisco activase?

Characterized by a photo-catalysis property, nano-anatase TiO2 is closely related to photosynthesis of spinach. It could not only improve light absorbance, transformation from light energy to electron energy and active chemical energy, but also promote the activity of Rubiso activase of spinach. However, the relation between the activity of Rubiso activase and the growth of spinach promoted by nano-anatase TiO2 treatment remains largely unclear. In this study, we find that the amount and the activity of Rubiso activase are obviously increased by nano-anatase TiO2 treatment, which led to the great promotion of Rubsico carboxylation and the high rate of photosynthesis, thus improving of spinach growth. The significant enhancement of Rubiso activase activity of nano-anatase TiO2 treated spinach is also accompanied by conformational changes as determined by spectroscopic analysis. But bulk TiO2 effect is not as significant as nano-anatase TiO2, as the grain size of nano-anatase TiO2 (5 nm) is much smaller than that of bulk TiO2, which entered spinach cell more easily.