A novel thermostable chitinase (PJC) from pomegranate (Punica granatum) juice

A novel chitinase was isolated and purified to its homogeneity from pomegranate juice by a combination of ammonium sulphate precipitation and ion-exchange chromatography. The pomegranate juice chitinase (PJC) was purified to specific activity of 14.5 U/mg and a recovery of 34%. The monomeric protein migrated on SDS–PAGE at 29 kDa. The enzyme was found to be glycosylated (7.2%). It exhibited optimal activity at pH 4.5 and 70 °C. The enzyme was stable in the pH range 3.0–9.0 and up to 65 °C. The internal peptide sequence results suggest that the purified PJC shared high homology with class III chitinases of other known plant chitinases. The purified enzyme could hydrolyse colloidal chitin to its oligomers. It did not exhibit any antifungal activity.

Research highlights
► A novel, monomeric chitinase was purified and characterised from pomegranate juice.
► It was glycosylated, with an optimal pH (pH 4.5) and optimal temperature (70 °C).
► The enzyme was thermostable and exhibited stability in a broad pH range.
► Internal peptide sequence shows high homology to GH family 18 class III chitinases.
► It possesses the ability to hydrolyse colloidal chitin into its oligomers.