Open AccessAtomic mutations in annexin V
Author(s) -
Budisa Nediljko,
Huber Robert,
Golbik Ralph,
Minks Caroline,
Weyher Elisabeth,
Moroder Luis
Publication year - 1998
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1046/j.1432-1327.1998.2530001.x
Subject(s) - guanidinium chloride , chemistry , crystallography , protein folding , selenium , methionine , amino acid , cysteine , denaturation (fissile materials) , folding (dsp implementation) , mutant , biochemistry , organic chemistry , enzyme , nuclear chemistry , gene , electrical engineering , engineering
We have recently developed methods for specific and high‐level replacement of methionine with 2‐aminohexanoic acid, selenomethionine and telluromethionine as isosteric and atomic analogues for structural investigations of human recombinant annexin V. The variants formed isomorphic crystals and retained the parent three‐dimensional fold and bioactivities. Folding parameters were determined from thermal and chemical unfolding to partially denatured states. Stabilities estimated from guanidinium chloride unfolding equilibria are not changed significantly for the atomic mutants (S←Se←Te) while the denaturation midpoint is shifted toward lower values with an increase of the m values at the increase of hydrophobicity. In contrast, stabilities in urea are considerably affected by the atomic substitutions, decreasing together with the m and [D] 1/2 values. The methylene and selenium variants are identical within the limits of error of all measurements performed here. The physical parameters of the amino acid analogues and the values derived from the slopes of the unfolding data are highly correlated. This approach demonstrates how systematic variations in atomic number at the site of replacement (atomic mutations) can provide a method to probe specific folding properties of proteins.