Amino Acids

, 36:633

Unfolding studies of tissue transglutaminase

  • Carlo Cervellati
  • Lorella Franzoni
  • Monica Squerzanti
  • Carlo M. Bergamini
  • Francesco Spinozzi
  • Paolo Mariani
  • Vincenzo Lanzara
  • Alberto Spisni
Original Article

DOI: 10.1007/s00726-008-0161-3

Cite this article as:
Cervellati, C., Franzoni, L., Squerzanti, M. et al. Amino Acids (2009) 36: 633. doi:10.1007/s00726-008-0161-3

Abstract

Activation of tissue transglutaminase by calcium involves a conformational change which allows exposition of the active site to the substrate via movements of domains 3 and 4 that lead to an increase of the inter-domain distance. The inhibitor GTP counteracts these changes. Here we investigate the possible existence of non-native conformational states still compatible with the enzyme activity produced by chemical and thermal perturbations. The results indicate that chemical denaturation is reversible at low guanidine concentrations but irreversible at high concentrations of guanidine. Indeed, at low guanidine concentrations tissue TG-ase exists in a non-native state which is still affected by the ligands as in the native form. In contrast, thermal unfolding is always irreversible, with aggregation and protein self-crosslinkage in the presence of calcium. DSC thermograms of the native protein in the absence of ligands consist of two partly overlapped transitions, which weaken in the presence of calcium and merge together and strengthen in the presence of GTP. Overall, the present work shows, for the first time, the reversible denaturation of a TG-ase isoenzyme and suggests the possibility that also in in vivo, the enzyme may acquire non-native conformations relevant to its patho-physiological functions.

Keywords

Tissue transglutaminase Denaturation Guanidine hydrochloride Thermal unfolding Differential scanning calorimetry Ligands 

Abbreviations

TG-ase

Transglutaminase

DSC

Differential scanning calorimetry

CD

Circular dichroism

Tm

Melting temperature

SAS

Small-angle-scattering

GdmHCl

Guanidinium hydrochloride

Copyright information

© Springer-Verlag 2008

Authors and Affiliations

  • Carlo Cervellati
    • 1
  • Lorella Franzoni
    • 2
  • Monica Squerzanti
    • 1
  • Carlo M. Bergamini
    • 1
  • Francesco Spinozzi
    • 3
  • Paolo Mariani
    • 3
  • Vincenzo Lanzara
    • 1
  • Alberto Spisni
    • 2
  1. 1.Department of Biochemistry and Molecular Biology, Interdisciplinary Centre for Study of InflammationUniversity of FerraraFerraraItaly
  2. 2.Department of Experimental Medicine, Section of Chemistry and Structural BiochemistryUniversity of ParmaParmaItaly
  3. 3.Department of Applied Science for Complex SystemsMarche Polytechnic UniversityAnconaItaly