NMR studies on parvalbumin phylogeny and ionic interactions

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Abstract
The inspection of several muscular parvalbumins from different species by two NMR methods (113Cd resonance and 1H relaxation measurements) allows two classes of parvalbumins to be distinguished according to their ion-binding properties. This result is in agreement with the phylogenetic classification of parvalbumins in two series, α and β, which was established on the basis of the primary structures of these proteins. All parvalbumins are characterized by the presence of two primary cationic sites CD and EF, with structural features closely related to those already known on the basis of X-ray crystallographic studies of the β parvalbumin pI 4.25 from carp muscle. However, parvalbumins of the β series are characterized by a secondary cation (Ca2+, Mg2+ and other cations) binding site which is absent (or at least inaccessible) in parvalbumins of the α series. The major component from thornback ray (pI 4.45) behaves as an α parvalbumin as shown by the present NMR studies, although its primary structure suggests a closer similarity with the parvalbumins of the β series.