Purification, characterisation, and gene cloning of transglutaminase from Streptoverticillium cinnamoneum CBS 683.68
Résumé
The transglutaminase (TGase; EC 2.3.2.13) from Streptoverticillium cinnamoneum CBS 683.68 has been purified, characterised and its gene cloned. The purified enzyme had a relative molecular mass of 37,660 determined by mass spectrometry and contained a single Cys residue that was essential for the catalytic activity. Contrary to eukaryotic TGases, this enzyme was calcium-independent. The fact that TGase was capable to incorporate a wide variety of aliphatic and aromatic non-polar compounds suggested that the amine fixation site could be an hydrophobic pocket. S cinnamoneum CBS 683.68 TGase was synthesised as a protein precursor of 411 amino acid residues corresponding to a signal peptide of 81 amino acid residues and a mature TGase of 330 amino acid residues. Amino acid sequence analysis revealed that the S cinnamoneum CBS 683.68 TGase had little sequence homology with eukaryotic TGases, but shared high identity with the sequence of Streptoverticillium strain S-8112. In accordance with kinetics data, hydropathy analysis showed that the active site of the enzyme was in an hydrophobic environment as for eukaryotic TGases.