Electron spin resonance (ESR) study on free radical transfer in fish lipid-protein interaction

Autor: Nazlin K. Howell, Susan A. Fawthrop, Suhur Saeed
Rok vydání: 1999
Předmět:
Zdroj: Journal of the Science of Food and Agriculture. 79:1809-1816
ISSN: 1097-0010
0022-5142
DOI: 10.1002/(sici)1097-0010(199910)79:13<1809::aid-jsfa440>3.0.co;2-v
Popis: Oxidised lipids interact with proteins causing undersirable changes in the nutritional and functional properties, including a loss of amino acids, cross-linking and damage to proteins and DNA. Proteins including egg lysozyme, egg ovalbumin, fish myosin and amino acids arginine, lysine and histidine were exposed to oxidised lipids methyl linoleate and oil extracted from Atlantic mackerel (Scomber scombrus). A strong central singlet signal was induced in the proteins and amino acids which was detected by ESR spectroscopy and assigned to the carbon radical (g value range 2.0021–2.0049); with ovalbumin and fish myosin a downfield shoulder, attributed to the sulphydryl group (g value 2.014–2.017), was also observed. The above changes in the proteins were accompanied by an increase in fluorescence indicating the formation of cross-links. Synthetic antioxidants such as butyl hydroxytoluene (BHT) and butyl hydroxyanisole (BHA) as well as natural antioxidants ascorbic acid and α-tocopherol inhibited the development of both the free radical signal and fluorescence when added to the proteins prior to incubation with oxidised lipids; the central singlet signal attributed to the carbon radical was reduced by 10–50%. This paper clearly indicates direct free radical transfer from oxidised lipids to amino acids and proteins which results in protein denaturation and the formation of insoluble aggregates in fish flesh on storage. © 1999 Society of Chemical Industry
Databáze: OpenAIRE
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