Sodium Sulphate Reactivates a Protein A Minidomain with a Short Elastin -Turn

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In this Subject: <a title="Anatomy & Physiology" href="/content/subcat?j_subject=157&j_availability=">Anatomy & Physiology ,&nbsp; Biology ,&nbsp; Biochemistry
By this author: Reiersen H. ;&nbsp; Rees A.R.

Authors: Reiersen H.; Rees A.R.

Source: Biochemical and Biophysical Research Communications, Volume 276, Number 3, October 2000 , pp. 899-904(6)

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Abstract:

Elastin polymer sequences derived from muscle exhibit temperature and salt-induced reversible contractions and expansions. A folded and contracted beta -turn helical elastin structure is stabilised by increased intramolecular hydrophobic interactions. We have generated a switchable binding protein by inserting a typical elastin turn sequence, GVPGVG, between the two IgG-binding helices of an engineered globular minidomain from Protein A. This mutant showed increased binding of IgG-molecules compared to the wild-type sequence in the presence of sodium sulphate, as measured by surface plasmon resonance spectroscopy. Analysis by circular dichroism revealed a salt-induced folding of the mutant minidomain to a native type I beta -turn, likely stabilised as a result of the two interacting dehydrated valines across the beta -turn. Since sodium sulphate can be successfully used to regulate the folding/unfolding or binding/dissociation of this minidomain, this suggests an alternative protein purification method. Copyright 2000 Academic Press.

Keywords: affinity; beta -turn; Biacore; CD; elastin; folding; helix; Protein A; sulphate; water