Abstract
Contrary to the majority of the members of the lipocalin family, which are stable monomers with the specific OBP fold (a β-barrel consisting of a 8-stranded anti-parallel β-sheet followed by a short ι-helical segment, a ninth β-strand, and a disordered C-terminal tail) and a conserved disulfide bond, bovine odorant-binding protein (bOBP) does not have such a disulfide bond and forms a domain-swapped dimer that involves crossing the ι-helical region from each monomer over the β-barrel of the other monomer. Furthermore, although natural bOBP isolated from bovine tissues exists as a stable domain-swapped dimer, recombinant bOBP has decreased dimerization potential and therefore exists as a mixture of monomeric and dimeric variants. In this article, we investigated the effect model crowding agents of similar chemical nature but different molecular mass on conformational stability of the recombinant bOBP. These experiments were conducted in order to shed light on the potential influence of model crowded environment on the unfolding-refolding equilibrium. To this end, we looked at the influence of PEG-600, PEG-4000, and PEG-12000 in concentrations of 80, 150, and 300 mg/mL on the equilibrium unfolding and refolding transitions induced in the recombinant bOBP by guanidine hydrochloride. We are showing here that the effect of crowding agents on the structure and conformational stability of the recombinant bOBP depends on the size of the crowder, with the smaller crowding agents being more effective in the stabilization of the bOBP native dimeric state against the guanidine hydrochloride denaturing action. This effect of the crowding agents is concentration dependent, with the high concentrations of the agents being more effective.
Highlights
Classical odorant binding proteins (OBPs) are intriguing members of the large lipocalin family, which, due to their ability to interact with different odorants (small hydrophobicHow to cite this article Stepanenko et al (2016), Structure and stability of recombinant bovine odorant-binding protein: III
BOBP unfolding in the presence of polyethylene glycol (PEG)-600 Previously, we have shown that denaturing curves describing guanidine hydrochloride (GdnHCl)-induced unfolding of bovine odorant-binding protein (bOBP) have a complex shape with two clearly distinguishable regions where the pattern of the different protein characteristics diverges significantly (Stepanenko et al, 2014b)
The conformational stability of bOBP was described in terms of the half-transition values (2.1 Âą 0.1 M GdnHCl, see Table 1) (Stepanenko et al, 2016c)
Summary
Classical odorant binding proteins (OBPs) are intriguing members of the large lipocalin family, which, due to their ability to interact with different odorants (small hydrophobicHow to cite this article Stepanenko et al (2016), Structure and stability of recombinant bovine odorant-binding protein: III. Bovine OBP (bOBP) has a unique dimeric structure, which is different from the monomeric OBP fold found in the majority classical OBPs (see Fig. 1) (Bianchet et al, 1996). Each protomer in the bOBP dimer forms a b-barrel via interaction with the a-helical region of another protomer by means of the domains swapping mechanism (Bianchet et al, 1996; Tegoni et al, 1996). The domain swapping mechanism, being described for several dimeric and oligomeric proteins, is known to play important structural and functional roles (Bennett, Schlunegger & Eisenberg, 1995; van der Wel, 2012). Early stages of the amyloid fibril formation are believed to be associated with the formation of domain-swapped oligomers (van der Wel, 2012)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
