The present review describes the methodology of perturbed angular correlation of gamma rays (PAC) applied to biological problems. A large part of the present review focuses on the application of PAC spectroscopy to the study of coordination geometry for the metal site in zinc enzymes. Applications to conformation and dynamics of biomolecules and the use of the method to identify the intracellular sites of either metals or labelled proteins are also discussed.

The non-invasive and non-destructive aspects of NMR and ESR spectroscopy have prompted a variety of research on the pathophysiological impact of murine malaria. NMR is unique in its ability to monitor intracellular pH non-invasively in a heterogeneous sample, a compartmentalized cell and in a whole organism. It has also been shown to be sensitive to unusual structures and metabolic products in free-living protozoa such as Acanthamoeba (Deslauriers et al. 1982a) and Tetrahymena (Deslauriers et al. 1982b; Jarrell et al. 1981). Using the appropriate spin probe, ESR can give valuable information on membrane structure (Schreier, Polnaszek & Smith; 1978). It is particularly useful when quantities of material are limited.