A brief history of bioEPR

The electron paramagnetic resonance effect was discovered in 1944 by E. K. Zavoisky in Kazan, in the Tartar republic of the then-USSR, as an outcome of what we would nowadays call a purely curiosity-driven research program apparently not directly related to WW-II associated technological developments (Kochelaev and Yablokov 1995). However, a surplus of radar components following the end of the war did boost the development of EPR spectroscopy, in particular, after the X-band ( X meaning to be kept a secret from the enemy) was entered in Oxford, U.K., in 1947 (Bagguley and Griffith 1947). 

Application to biomolecules started as early as the mid-fifties with single-crystal EPR studies on hemoglobin (Bennett et al. 1955), but in hindsight it now appears that 

It would appear that the determination of the haem plane orientations by paramagnetic resonance is much more accurate than that by any other method so far applied. 

For a balanced historical record I should add that the late W. E. Blumberg has been cited to state (W. R. Dunham, personal communication) that One does not need the Aasa factor if one does not make the Aasa mistake, by which Bill meant to say that if one simulates powder spectra with proper energy matrix diagonalization (as he apparently did in the late 1960s in the Bell Telephone Laboratories in Murray Hill, New Jersey), instead of with an analytical expression from perturbation theory, then the correction factor does not apply. What this all means I hope to make clear later in the course of this book. 

The above historical outline refers mainly to the EPR of transition ions. Key events in the development of radical bioEPR were the synthesis and binding to biomolecules of stable spin labels in 1965 in Stanford (e.g., Griffith and McConnell 1966) and the discovery of spin traps in the second half of the 1960s by the groups of M. Iwamura and N. Inamoto in Tokyo A. Mackor et al. in Amsterdam and E. G. Janzen and B. J. Blackburn in Athens, Georgia (e.g., Janzen 1971), and their subsequent application in biological systems by J. R. Harbour and J. R. Bolton in London, Ontario (Harbour and Bolton 1975). 

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