Purification and Characterization of Extracellular Poly(β-hydroxybutyrate) Depolymerase from Penicillium sp. DS9701-D2

Abstract

An extracellular poly (β-hydroxybutyrate) (PHB) depolymerase was purified from Penicillium sp. DS9701-D2. The molecular weight of the enzyme was estimated to be about 46.8 KDa by sodium dodecyl sulfate—polyacrylamide gel electrophoresis. The isoelectric point of 7.6 for the enzyme was determined by capillary electrophoresis. The optimum enzyme activity was detected at 30°C and pH 5.0. It was found that Na⁺ and K⁺ enhance the enzyme activity, whereas Zn²⁺, Mg²⁺, Cu²⁺, and Fe²⁺ inhibit it. The secondary structure of the enzyme was measured by circular dichroism (CD) spectroscopy. The main degradation product of depolymerase was indentified as 3-hydroxybutyrate dimer by mass spectrometer (MS) analysis.

Keywords:

• Depolymerase
• penicillium
• poly(β-hydroxybutyrate)