Hybrid complexes of photosynthetic reaction centers and quantum dots in various matrices: resistance to UV irradiation and heating

Abstract

The effects of ultraviolet (UV) irradiation (up to 0.6 J/cm) and heating (65 °C, 20 min) on the absorption spectra and electron transfer in dehydrated film samples of photosynthetic reaction centers (RCs) from purple bacterium Rhodobacter (Rb.) sphaeroides, as well as in hybrid structures consisting of RCs and quantum dots (QDs), have been studied. The samples were placed in organic matrices containing the stabilizers of protein structure-polyvinyl alcohol (PVA) and trehalose. UV irradiation led to partially irreversible oxidation of some RCs, as well as to transformation of some fraction of the bacteriochlorophyll (BChl) molecules into bacteriopheophytin (BPheo) molecules. In addition, UV irradiation causes degradation of some BChl molecules that is accompanied by formation of 3-acetyl-chlorophyll a molecules. Finally, UV irradiation destroys the RCs carotenoid molecules. The incorporation of RCs into organic matrices reduced pheophytinization. Trehalose was especially efficient in reducing the damage to the carotenoid and BChl molecules caused by UV irradiation. Hybrid films containing RC + QD were more stable to pheophytinization upon UV irradiation. However, the presence of QDs in films did not affect the processes of carotenoid destruction. The efficiency of the electronic excitation energy transfer from QD to P865 also did not change under UV irradiation. Heating led to dramatic destruction of the RCs structure and bacteriochlorins acquired the properties of unbound molecules. Trehalose provided strong protection against destruction of the RCs and hybrid (RC + QD) complexes.

The Rhododendron Chrysanthum Pall.s’ Acetylation Modification of Rubisco Enzymes Controls Carbon Cycling to Withstand UV−B Stress

“…Most plants that are exposed to UV−B radiation will react by producing stress [ 3 ]. According to pertinent research, UV−B stress can harm plants in a number of ways, including slowing down their growth, inhibiting photosynthesis, oxidative damage, and rupturing the integrity of vital macromolecules [ 4 , 5 , 6 ]. Green plants’ rate of photosynthetic activity may be significantly lowered by UV−B stress [ 7 ], and parameters connected to chlorophyll fluorescence are crucial markers of photosynthetic characteristics [ 8 ].…”

Metabolic programming of Rhododendron chrysanthum leaves following exposure to UVB irradiation

“…It is now widely known that the increased influx of UVB (280-315 nm) irradiation is primarily due to stratospheric ozone depletion (Kusano et al 2011). High UVB radiation levels cause macromolecules disruption, ROS production, inhibition of photosynthesis and growth reduction (Knox et al 2019). Plants implement various strategies to combat the UVB stress conditions.…”