Biophysical characterization of recombinant human ameloblastin

Wald T, Bednárová L, Osička R, Pachl P, Šulc M, Lyngstadaas SP, Slaby I, Vondrášek J. Biophysical characterization of recombinant human ameloblastin. Eur J Oral Sci 2011; 119 (Suppl. 1): 261–269. © 2011 Eur J Oral Sci Ameloblastin (AMBN) is a protein expressed mainly during dental hard tissue development. Biochemically, it is classified as an intrinsically disordered protein (IDP). Its biological role remains largely unknown; however, the question of AMBN function will undoubtedly be connected to its structural properties and its potential for protein–protein and protein–cell interactions. A basic biophysical characterization of human recombinant ameloblastin (hrAMBN) and its N‐ and C‐terminal domains by means of circular dichroism spectroscopy and dynamic light scattering showed that under physiological conditions ameloblastin is an IDP with a prevalent polyproline‐II (PPII) conformation. Both the N‐ and C‐terminal polypeptides, when expressed independently, showed different structural preferences upon heating as well as different behaviour in the presence of trifluoroethanol and CaCl2 salt. The N‐terminal peptide showed a more ordered structure with a strong tendency to adopt a helical conformation upon the addition of trifluorethanol, whereas the C‐terminal domain seemed to be primarily responsible for the structural disorder of the entire AMBN molecule.