Electron spin resonance study of the metal binding site of glucose specific peripheral blood lymphocyte lectin

The electron spin resonance (ESR) spectrum of Mn2+ is highly responsive to changes in coordination symmetry. We have thus used ESR spectroscopy to study Mn2+ bound to goat peripheral blood lymphocyte lectin to delineate the nature of the metal binding site of the lectin. Our results suggest the presence of two metal binding sites on goat peripheral blood lymphocyte lectin, one a dissociable site which could bind Cu2+, Ca2+, Mg2+ and Ni2+ to displace bound Mn2+ and the other a non-dissociable site from which bound Mn2+ could not be displaced. Since no spectral changes are observed when D-glucose is bound, it is unlikely that Mn2+ participates directly in saccharide binding.