ROUBAL and COLLIER: SPIN-LABELING TECHNIQUES 



ganization is considered to involve alterations in 

 these properties. Accordingly, on invasion of 

 membrane primarily by aromatics, surface per- 

 turbations as indicated by spin-labeling spectra 

 reflect changes in ion-binding properties of 

 phospholipid headgroups, enzyme activity, and 

 permeability changes. 



From the standpoint of membranes, paraffins 

 are tolerated up to a point, by shunting them into 

 internal reaches of membrane, away from active 

 metabolic processes. Our spin-labeling studies 

 show lipid fluidity to be altered when tissue is 

 exposed to parafl!ins. These changes are rather 

 diffuse, however, and not associated with any one 

 portion of the membrane interior. Such alterations 

 however, could be operative in altering ion trans- 

 port. 



We contend, therefore, that aromatic- 

 membrane interaction is of paramount concern. 

 This is especially true when behavioral/ 

 physiological patterns are to be explained. Addi- 

 tional insight into these areas will necessitate 

 further biophysical studies— both spin-labeling 

 and broad-based electrophysiological studies. 



FUTURE OUTLOOK ON 

 SPIN-LABELING 



Spin-labeling was first described only as 

 recently as about 1968. Since then, a vast array of 

 labels have been described. New instrumentation 

 has evolved, and the technique has grown from a 

 tool of limited application to one of major impor- 

 tance. For many biochemical and biophysical 

 studies, the technique stands prominently above 

 other methods. Applied to drug studies, phar- 

 macology, immunology, cancer research, en- 

 zymology, and protein structure studies, spin- 

 labeling promises to play an ever growing role. 



Environmentalists, biologists, zoologists, and food 

 scientists now apply this tool to their studies. The 

 future of spin-labeling is bright indeed. 



LITERATURE CITED 



Green, D. E. 



1972. Membrane proteins: A perspective. Ann. N.Y. Acad. 

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HUBBELL, W. L., AND H. M. McCONNELL. 



1969. Motion of steroid spin labels in membranes. Proc. 

 Natl. Acad. Sci. 63:16-22. 



JOST, P., L. J. LiBERTINI, AND V. C. HERBERT. 



1971. Lipid spin labels in lecithin multilayers. A study of 

 motion along fatty acid chains. J. Mol. Biol. 59:77-98. 

 KiER, L. B. 



1971. Molecular orbital theory in drug research. Academic 

 Press, N.Y., p. 137-161. 



LiBERTINI, L. J., A. S. Waggoner, P. C. Jost, and 0. H. Griffith. 

 1969. Orientation of lipid spin labels in lecithin mul- 

 tilayers. Proc. Natl. Acad. Sci. 64:13-19. 

 ROUBAL, W. T. 



1972. Spin-labeling with nitroxide compounds. A new 

 approach to the in vivo and in vitro study of lipid-protein 

 interaction. In R. T. Holman (editor), Progress in the 

 chemistry of fats and other lipids, 13:61-86. Pergamon 

 Press, Long. 



1974a. In vivo and in vitro spin-labeling studies of pollu- 

 tant-host interaction. In R. Haque and F. J. Biros (edi- 

 tors), Mass spectrometry and NMR spectroscopy in pes- 

 ticide chemistry, p. 305-324. Plenum Press, N.Y. 

 1974b. Spin-labeling of living tissue. In E. J. Vernberg 

 (editor), Pollution and physiology of marine organisms, p. 

 367-379. Academic Press, N.Y. 

 RouBAL, W. T., H. M. Etlinger, and H. 0. Hodgins. 



1974. Spin-label studies of a hapten-combining site in rain- 

 bow trout antibody. J. Immunol. 113:309-315. 

 Schreier-Muccillo, S., D. Marsh, H. Dugas, H. Schneider, and 

 L C. P. Smith. 



1973. A spin probe study of the influence of cholesterol on 

 motion and orientation of phospholipids in oriented mul- 

 tibilayers and vesicles. Chem. Phys. Lipids 10:11-27. 



Singer, S. J. 



1972. A fluid lipid-globular protein mosaic model of 

 membrane structure. Ann. N.Y. Acad. Sci. 195:16-23. 



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