Effects of his-tags on physical properties of parvalbumins.

ABSTRACT

A comparative study of His-tagged and non-tagged rat ß-parvalbumin (rWT ß-PA), calcium binding protein with the EF-hand calcium binding domains, has been carried out. The attachment of His-tag increases α-helical content and decreases ß-sheets and ß-turns content of the metal free form (apo-state) of ß-PA. In contrast to this, the attachment of His-tag decreases α-helical content by more than 10% and increases contents of ß-sheets and ß-turns of the Ca2+-loaded state. According to the dynamic light scattering analysis, apo-state of His-tagged rat ß-PA seems to be less compact compared with the apo-state of non-tagged rat ß-PA. Surprisingly, the attachment of His-tag practically does not change mean hydrodynamic radius of Ca2+-loaded rat ß-PA. The attachment of His-tag shifts thermal denaturation peaks of both apo- and Ca2+-loaded states of rat ß-PA towards higher temperatures by 3-4 °C and slightly decreases its Ca2+ affinity. These results should be taken into consideration in the use of His-tagged parvalbumins.