Fluorescence Quenching Of Phycobiliprotein By Orange Carotenoid Protein And Its Application

Cyanobacteria have made important contributions to global photosynthesis.The balance between efficient use of light and excessive destruction of light is the key to efficient photosynthesis.Non-photochemical quenching（NPQ）is a short-term adaptive reaction to increasing illumination.In many blue-green algae,NPQ involves orange carotenoid protein（OCP）which can inhibit the overexcitation of their extracellular light-collecting complexes（Phycobilisome,PBS）for protecting the light system.This topic mainly focuses on the discussion of NPQ mechanism regulated by OCP,exploring the role of OCP in fluorescence quenching and the industrial production of derivative products.Recombinant phycobilisome nuclear trimer protein,phycobiliprotein subunit（PBPs）,photochromic domain protein and fluorescent protein in E.coli BL21,and then analyzed,determined and calculated related parameters.The effects of OCP stable state（OCP^O）,OCP activated state（OCP^R）and OCP permanently activated state mutant(OCP^W288A)on fluorescence quenching were investigated by Gaussian fitting curve.At the same time,the resistance of OCP^WT and OCP^W288A to UV-B under 312 nm ultraviolet light source was studied.In vitro quenching of protein fluorescence by stable state OCP^O,activated state OCP^R and permanently activated state mutant OCP^W288A was compared.The experimental results show that OCP^O,OCP^R and OCP^W288A all have good fluorescence quenching effect in the corresponding fluorescence quenching range of the three OCPs,and are good fluorescence quenching agents.Compared with OCP^O,the maximum absorption peak values of quenching protein fluorescence by OCP^W288A and OCP^R were redshifted by 11 nm and 1 nm,respectively.The quench range of OCP^O is wider than that of OCP^R,but the quench efficiency of OCP^R is nearly 50%higher than that of OCP^O,which makes it effective in NPQ.At the same time,it was found that OCP^WTwith a final concentration of 40μmol/L had a higher degree of protection against E.coli at OD_{600 nm}=0.5988 concentration under the irradiation of 312 nm UV light source,while OCP^W288A had no protective effect against E.coli at OD_{600 nm}=0.5988concentration.The results showed that OCP^WT had strong resistance against 312 nm UV light source.Therefore,OCP^WT as a sunscreen factor,non-toxic and natural protein components,OCP^WT has the potential to be an ideal photoprotective material.This topic has important biological significance in the study of artificial photosynthesis.It is beneficial to promote the development of bionic photoprotective materials and provide natural effective ingredients for chemical sunscreen.It provides a new direction and idea for the research of low cost and pollution-free UV filter,so as to realize the industrial production of safe,efficient and environmentally friendly chemical sunscreen products.