Effects of carotenoids from Deinococcus radiodurans on protein oxidation
2009
Tian, B. | Sun, Z. | Shen, S. | Wang, H. | Jiao, J. | Wang, L. | Hu, Y. | Hua, Y.
To evaluate the antioxidant effect of carotenoids from Deinococcus radiodurans on protein. Deinococcus radiodurans strain R1 (ATCC 13939) and its mutant strain R1ΔcrtB were used for this study. The total carotenoids (R1ex) from D. radiodurans were obtained by extraction with acetone/methanol (7 : 2, by vol), and their antioxidant activity was measured using the DPPH[dot above] (2,2-diphenyl-1-picrylhydrazyl) system. The protein oxidation level, in vitro and in the cell, was measured using the DNPH (2,4-dinitrophenyl hydrazine) method. The carotenoid extract R1ex scavenged 40·2% DPPH[dot above] radicals compared to β-carotene (31·7%) at a concentration of 0·5 mg ml⁻¹. The intracellular level of protein oxidation in mutant R1ΔcrtB, which does not contain carotenoid, was 0·0212 mmol mg⁻¹ protein which is significantly greater than that in the wild type (0·0169 mmol mg⁻¹ protein) following the treatment with H₂O₂. The purified major carotenoid product (deinoxanthin) from the wild type showed a greater inhibition of oxidative damage in bovine serum albumin than lycopene or lutein. Carotenoids prevent protein oxidation and contribute to the resistance to cell damage in D. radiodurans. Our results provide the evidence that carotenoids can protect proteins in D. radiodurans against oxidative stress.
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