Purification, Characterization and Kinetic Studies of a Novel Poly(β) Hydroxybutyrate (PHB) Depolymerase PhaZPen from Penicillium citrinum S2

• Published in: Applied biochemistry and biotechnology Vol. 164; no. 8; pp. 1225 - 1236
• Main Authors: Shivakumar, Srividya, Jagadish, Sneha Jani, Zatakia, Hardik, Dutta, Jayasmita
• Format: Journal Article
• Language: English
• Published: New York Humana Press Inc 01.08.2011; Springer
• Subjects: Biochemistry; Biological and medical sciences; Biotechnology; Chemistry; Chemistry and Materials Science; Fundamental and applied biological sciences. Psychology; PHB depolymerase; Characterization; Purification; Kinetic studies; Fungi; P. citritium; Butyrate(hydroxy)polymer; Fungi Imperfecti; Kinetics; Penicillium citrinum
• ISSN: 0273-2289; 1559-0291
• DOI: 10.1007/s12010-011-9208-0

A fungal isolate, identified as Penicillium citrinum S2, produced ≈1 U/mL of PHB depolymerase by 72 h when grown in BHM containing 0.2%, w / v PHB, pH 6.0 at 30 °C. Partial purification of an extracellular poly(-β-)hydroxybutyrate (PHB) depolymerase PhaZ Pen from P. citrinum S2 by two steps using ammonium sulphate (80% saturation) and affinity chromatography using concanavalin A yielded 16.18-fold purity and 21.53% recovery of protein. The enzyme was composed of three polypeptide chains of 66, 43 and 20 kDa, respectively, as determined by sodium dodecyl sulphate-polyacrylamide gel electrophoresis. All the three bands stained positive for glycoprotein by PAS staining. Optimum enzyme activity was detected at pH 6.0 and 50 °C. The enzyme was stable between pH 4.0 and 7.0 at 50 °C, 2 h. β-hydroxybutyrate monomer was detected as the major end product of PHB hydrolysis. The enzyme also showed distinct behaviour towards different inhibitors tested, which suggests the role of serine, serine residue, carboxyl group, tyrosine and sulfhydryl groups in its active site.