Dimerization of human recombinant resistin involves covalent and noncovalent interactions

Abstract

Resistin, an adipocyte secreted cysteine rich hormone has been implicated as molecular link between obesity and type 2 diabetes in a murine model. Although, at the protein level mouse and human resistin show remarkable similarities with respect to conserved cysteine residues, the physiological role of human resistin is not yet clear. In the present study we describe the purification and refolding of human recombinant resistin using two different refolding processes. Gel filtration analysis of protein refolded by both the methods revealed that human recombinant resistin, like mouse resistin, has a tendency to form dimers. Interestingly, dimerization of resistin appears to be mediated by both covalent (disulfide bond mediated) and non-covalent interactions as seen on reducing and non-reducing SDS–PAGE. Circular dichroism spectral analysis revealed that human resistin peptide backbone is a mixture of α-helical and β-sheet conformation with significant amounts of unordered structure, similar to the mouse resistin. It is likely that the first cysteine (Cyst 22) of human resistin, which is equivalent to mouse Cyst 26, may be involved in stabilizing the dimers through covalent interaction.