FISHERY BULLETIN': VOL, 69, NO, 2 



RESULTS AND DISCUSSION 

 ELECTRON MIGRATION IN PROTEINS 



As a base for comparing EPR signals in pro- 

 cessed food materials, it will be instructive at 

 this point to consider briefly the mechanism (s) 

 which may be operative (disregarding for the 

 moment, lipid oxidation) in the production of 

 the observed signals in carefully freeze-dried 

 tissue. In recent years, considerable attention 

 has been given to the idea of the migration of 

 energy over comparatively long distances in 

 cells; such transfer of electrons is implicated 

 in the process of mutation by ionizing radiation, 

 in the process of nerve conduction, and in cer- 

 tain biochemical photo dissociations. There are 

 problems of a theoretical nature associated with 

 such hyi^otheses, and these are reviewed in the 

 discussions of Blyumenfel'd (1957). 



Terenin (1947) and Terenin and Krasnovskii 

 (1949) have criticized Szent-Gyorgyi's hypo- 

 thesis that electrons move along the protein 

 polypeptide backbone in conductivity bands 

 analoguous to the movement of electrons in 

 conductivity bands of semiconducting metals. 

 Although polypeptide chains e.xhibit properties 

 reminiscent of conjugated unsaturation, Terenin 

 poses the interesting observation that some 70 

 kcal/mole, a large amount of energy, would 

 be required to mobilize electrons; evidently 

 at usual temperatures, conductivity bands are 

 empty. 



Notwithstanding the fundamental objections 

 to energy migration in native proteins, Blyumen- 

 fel'd (1957) considered the participation of 

 triplet states in energy transfer, a possibility 

 that is partially confirmed by the fact that the 

 phosphorescence spectrum of proteins lies in 

 the region of 4000 A and corresponds closely 

 to the calculated excitation energy which would 

 be sufficient for energy transfer across molecu- 

 lar orbitals originating within the framework 

 of hydrogen bonds. However, in the absence of 

 prosthetic groups, it seems reasonable that few, 

 if any, electrons would be free for mobilization. 

 When prosthetic grouiis are present, however, 

 and when they lie close to those of the ])rotein 

 (energetically speaking), electrons could be 



transferred into low lying orbitals of protein. 

 Once in these molecular orbitals, the forbidden 

 triplet transition to the singlet ground state 

 would tend to maintain electrons in the triplet 

 state energy levels. Under these circumstances, 

 the electron would move along a chain of pep- 

 tide hydrogen bonds until disposed of into some 

 other favorably bound group. 



RADICAL CONTENT IN PROCESSED 

 FISHERY MATERIALS 



For conventionally processed foodstuffs, tis- 

 sues, and meals (that is, solvent-extracted pro- 

 teins or proteins processed at room tempera- 

 ture) , the situation is quite difl'erent. No longer 

 do we have a protein substance identical in 

 character to the native material; bonds have 

 been broken, and the original geometrical ar- 

 rangement of the protein chains has been com- 

 pletely disrujjted. In many instances, certain 

 compounds or classes of compounds have been 

 selectively removed while at other times other 

 substances are purposely added back to the pro- 

 tein. 



Interestingly, the present study has shown 

 that such materials as protein concentrates con- 

 taining some residual lipid, fish meal, and freeze- 

 dried tissue samples not processed with utmost 

 caution in the freezing and freeze-drying steps, 

 all exhibit characteristic EPR signals when e.\- 

 posed to air. Indeed, it is generally true that the 

 radical content of haphazardly handled ma- 

 terials is usually higher than for an equal weight 

 of similar material which has been processed 

 by careful handling, freezing in liquid nitrogen, 

 and careful removal of water. Unable to mi- 

 grate along conductive pathways, effective 

 charge ti-ansfer to radicals from donor mole- 

 cules or reactants is apparently reduced (thus 

 the radicals act as though caged or matrixed) 

 and no longer do radicals interact freely with 

 one another nor do they react at once with 

 other cellular constituents. However, the ef- 

 ficiency in the reduction of charge transfer un- 

 doubtedly depends on the nature of the sample 

 and its treatment. Just how immobilized such 

 radicals are is open to conjecture. They are im- 



372 



