Spectroscopic and thermodynamic properties of Debaryomyces hansenii UFV-1 α-galactosidases

Abstract

Spectroscopic and thermodynamic properties were determined for Debaryomyces hansenii UFV-1 extracellular and intracellular α-galactosidases. α-Galactosidases showed similar secondary structure compositions (α-helix, β-sheet parallel and β-turn). Effects of pH and temperature on the structure of α-galactosidases were investigated using circular dichroism spectroscopy. It was more pronounced at low pH. Microcalorimetry was employed for the determination of thermodynamic parameters. Immediate thermal denaturation reversibility was not observed for α-galactosidases; it occurred as a thermodynamically driven process. Extracellular α-galactosidase, at pH 5.5, showed lower Tm when compared to the intracellular enzyme. The CD and DSC data suggest that D. hansenii α-galactosidases have different behaviors although they possess some similar secondary structures.