Electron paramagnetic resonance in biology.

A review of the theories of electron paramagnetic resonance in biology is presented, including a discussion of the nature of the physical observation, followed by examples of materials of biological interest. Iq discussing these examples, information is presented in terms of the nature of the starting material under observation rather than the nature of the magnetic entities observed. The examples proceed from the simpler molecules of biological interest (metabolites, vitamins, cofactors) into the more complex materials (polymers, proteins, nucleic acids) toward cellular organelles (mitochondria, chloroplasts) and, finally, to whole cells, organisms and organs. The observation of photoinduced unpaired electrons in photosynthetic material is described and the various parameters controlling it are discussed. The basic observation is interpreted in terms of a primary photophysical act of quantum conversion. * Presented at First International Biophysics Congress, Stockholm, Sweden, July 31-Aug. 5, 1961. ** The preparation of this paper was sponsored by the U.S. Atomic Energy Commission. -)(:;L:;crl'~WN Pf.W\lV,CN~'l'IC m:SONANC:~ IN BIOLOCY ·x·* G. 11. Aldrocr; and Melvin Calvin **.)(Ik'p81'tLlcnt 0:1 ChcnrLstry CElCI Lm,rrence HadiBtion Laboratory lLlivc;rsity 01' California, Berkeley 4, CalU'ornia * PreSt.mtcd at First International Biophysics Conc;ress, Stockholm, Sweden, July 31-August 5, 1961. ** Research Professor 0:[' Chemistry in the Hiller Institute for Basic Research in Science, University of' California, Berkeley. *** The preparation of this paper was sponsored by the U.S. Atomic Energy Commission.