The chondroitin sulfate/dermatan sulfate 4-O-endosulfatase from marine bacterium Vibrio sp FC509 is a dimeric species: Biophysical characterization of an endosulfatase.

Sulfatases catalyze hydrolysis of sulfate groups. They have a key role in regulating the sulfation states that determine the function of several scaffold molecules. Currently, there are no studies of the conformational stability of endosulfatases. In this work, we describe the structural features and conformational stability of a 4-O-endosulfatase (EndoV) from a marine bacterium, which removes specifically the 4-O-sulfate from chondroitin sulfate/dermatan sulfate. For that purpose, we have used several biophysical techniques, namely, fluorescence, circular dichroism (CD), FTIR spectroscopy, analytical ultracentrifugation (AUC), differential scanning calorimetry (DSC), mass spectrometry (MS), dynamic light scattering (DLS) and size exclusion chromatography (SEC). The protein was a dimer with an elongated shape. EndoV acquired a native-like structure in a narrow pH range (7.0-9.0); it is within this range where the protein shows the maximum of enzymatic activity. The dimerization did not involve the presence of disulphide-bridges as suggested by AUC, SEC and DLS experiments in the presence of β-mercaptoethanol (β-ME). EndoV secondary structure is formed by a mixture of α and β-sheet topology, as judged by deconvolution of CD and FTIR spectra. Thermal and chemical denaturations showed irreversibility and the former indicates that protein did not unfold completely during heating.