Comparative study of physiochemical properties of two pike parvalbumins by means of their intrinsic tyrosyl and phenylalanyl fluorescence.

Physicochemical properties of two pike parvalbumins (pI 5.0 and 4.2), belonging to two different gene lineages, have been studied by their intrinsic tyrosine and phenylalanine fluorescence. The CD sites of these paravalbumins have similar affinities to Ca2+ (and Mg2+) ions, but the EF sites of the proteins have very different affinities to these ions. This results in differing stabilities of these parvalbumins to pH-, urea-, and temperature-induced denaturation. The structure of pike parvalbumin pI 5.0, which binds Ca2+, and Mg2+ ions more tightly, is more stable than that of parvalbumin pI 4.2. Both proteins have higher affinities for Na+ ions than for K+ ions.