FISHERY BULLETIN: VOL. 69, NO. 2 



Other radicals, however, may make some small 

 contribution to the central resonance pattern. 

 A recent investigation by Wekell and RoubaP 

 has shown that free radicals arise during car- 

 bony] amine browning. What is more, although 

 hfs is seen in early stages of the browning, the 

 signal changes to a single line in the g = 2 re- 

 gion as polymerization progresses. The brown- 

 ing reaction, without the implication of free 

 radicals in lipid-protein systems, though not a 

 dominant pathway to pigments, was first dis- 

 cussed by Venolia and Tappel (1958) as a pos- 

 sible cause of color formation during the ox- 

 idation of such systems [but because the more 

 recent work, polymeric masses are, for the 

 most pai-t, attributed to lipid peroxy induced 

 protein-protein polymerization together with 

 malonaldehyde cross-linked proteins (conju- 

 gated Schiff base)]. 



Thus, although recent studies in this labora- 

 tory have uncovered new facts concerning rad- 

 icals in lipid-protein systems, the exact nature 

 of the resonances observed in freeze-dried tis- 

 sue and in dry model mixtures remains to be 

 fully characterized. Nonetheless, this pioneer- 

 ing piece of research has paved the way for use 

 of EPR studies in systems of oxidizing lipids 

 together with other cellular constituents. Con- 

 current studies have shown that transition metal 

 ion impurities, if present, play only a minor role 

 in radical production. Other studies of this lab- 

 oratory have shown that pi-otein-free fish bone 

 does not give EPR signals. Freshly prepared 

 freeze-dried tissue samples give no lipid signal 

 resonances, but signal amplitudes grow on ex- 

 posure to oxygen. Depending on the type of 

 l)rotein, type and amount of lipid, or added ma- 

 terial, lipid signals exhibit various lifetimes 

 ranging from hours to years. (For instance, 

 compare Figure Ic for BSA with Figure 2b 

 for 2-year-old FPC.) Polysaccharides are only 

 partially effective as radical matrices. 



For living systems, or for any system con- 

 taining residual and unprotected oxidizable lipid, 

 the implications of the various interactions dis- 

 cussed are significant. It is known that products 

 of lipid oxidation in lipid-protein systems inter- 



' Unpublished data; to be published. 



act with proteins, enzymes, and nucleotides. Not 

 only are these native biopolymers further poly- 

 merized by such interactions, constituent build- 

 ing blocks are destroyed (Roubal and Tappel, 

 1966b, 1967) ; notable are the sulfur amino acids 

 which have been shown to be easily destroyed 

 by free radicals (Roubal and Tappel, 1966a). 

 In this presentation I have not discussed con- 

 sequences of unwanted lipid peroxidation in nu- 

 tritional deficiency states or in other pathol- 

 ogies in living systems. Nevertheless, such 

 lipid-protein interaction is quite significant. The 

 geronotological implications of these reactions 

 leading to the formation of age pigments, based 

 on studies of Roubal and Tappel (1966b) and 

 others, have been reviewed by Bjorksten (1965) , 

 Packer, Deamer, and Heath (1967), and Tappel 

 (1968). 



LITERATURE CITED 



Bjorksten, J. 



1965. Thirteen-year report on the studies on aging 

 (1952-1965). Bjorksten Res. Found. Rep. Mad- 

 ison, Wis., 23 p. 



Blyumenfel'd, L. a. 



1957. Paramagnetic resonance spectra of biolo- 

 gical objects and migration of energy. [In Rus- 

 sian.] Izv. Akad. Nauk SSSR, Ser. Biol. No. 3: 

 285-292. (Translation, Clearinghouse, Fed. Sci. 

 Tech. Inform., Springfield, Va., as OTS 61-19575.) 



Chetverikov, a. G., L. A. Blvtjmenfel'd, and G. V. 



FOMIN. 



1965. Possible mechanisms of formation and de- 

 struction of free radical states in cells. Bio- 

 physics 10: 526-538. (Translated from Biofizika 

 10: 476-486.) 

 Packer, L., D. W. Deamer, and R. L. Heath. 



1967. Regulation of deterioration of structure in 

 membranes. In B. L. Strehler (editor), Advan. 

 Gerontol. Res. 2: 77-120. Academic Press, New 

 York. 

 Roubal, W. T. 



1970. Trapped radicals in dry lipid-protein sys- 

 tems undergoing oxidation. J. Amer. Oil Chem. 

 Soc. 47: 141-144. 

 Roubal, W. T., and A. L. Tappel. 



1966a. Damage to proteins, enzj-mes, and amino 

 acids by peroxidizing lipids. Arch. Biochem. Bio- 

 phys. 113: 5-8. 



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