Optically detected magnetic resonance tryptophan

J. Zuclich, D. Schweitzer, and A. H. Maki, Optically detected magnetic resonance of the tryptophan phosphorescent state in proteins, Photochem. Photobiol. 18, 161-168 (1973). 

K. Ugurbil, A. H. Maki, and R. Bersohn, Study of the triplet state properties of tyrosines and tryptophan in azurins using optically detected magnetic resonance, Biochemistry 16, 901-907 (1977). 

K. L. Bell and H. C. Brenner, Phosphorescence and optically detected magnetic resonance study of the tryptophan residue in human serum albumin, Biochemistry 21, 799-804 (1982). 

M. V. Hershberger, A. H. Maki, and W. C. Galley, Phosphorescence and optically detected magnetic resonance studies of a class of anomalous tryptophan residues in globular proteins, Biochemistry 19, 2204—2209 (1980). 

Rousslang and co-workers (1978, 1979) and Ross and co-workers (1980) used optically detected magnetic resonance (ODMR) of tryptophan triplet states to detect conformational variations in proteins and polypeptides. This method used in combination with phosphorescence appears to be an excellent probe for detection of conformational variations which affect the environment of tryptophan. 

To our knowledge the first appheation of ODMR to a molecule of biological importance was made by Kwiram who in 1970 reported the optical detection of magnetic resonance signals from the tryptophan moiety of lysozyme. A more recent report dealt with frozen glassy solutions of tryptophan, tyrosine, and the protein, bovine serum albumin (BSA) loob) See Fig. 10. Discrepancies between the lifetimes involved in the phosphorescence decay and the fast-passage ODMR responses... 

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