Poly-β-hydroxybutyrate (PHB)‎ Depolymerase from Fusarium solani Thom

الملخص EN

Fusarium solani Thom produced maximum PHB depolymerase by 48 h when grown in BHM containing 0.2%, w/v PHB, pH 8.0 at 25°C.

Statistical optimization studies using Plackett Burman design of PHB depolymerase production yielded maximum PHB depolymerase activity after 2 days as against 4 days in the unoptimized conditions with a 2-fold increase in activity.

Partial purification of the extracellular poly-β-hydroxybutyrate (PHB) depolymerase PHAZFus from F.

solani Thom by two steps using ammonium sulphate (80% saturation) and affinity chromatography using concanavalin-A yielded 162.3-fold purity and 63% recovery of protein.

The enzyme composed of a single polypeptide chain of 85 KDa, as determined by SDS-PAGE.

The enzyme stained positive for glycoprotein by PAS staining.

Optimum enzyme activity was detected at pH 7.0 and 55°C.

The enzyme was stable at pH 7.0 and 55°C for 24 h with a residual activity of almost 85%.

Paper chromatography revealed β-hydroxybutyrate monomer as the major end product of PHB hydrolysis.

Complete inhibition of the enzyme by 1 mM HgCl2 (100%) indicated the importance of essential disulfide bonds (cystine residues) for enzyme activity or probably for maintaining the native enzyme structure.