A Lysozyme with Antifungal Activity from Pithecellobium dulce Seeds

Narumon Sawasdipuksa¹, Zhentian Lei², Lloyd W. Sumner², Ploypat Niyomploy³ and Polkit Sangvanich¹*

¹Research Centre for Bioorganic Chemistry, Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand
²Plant Biology Division, The Samuel Roberts Noble Foundation, Ardmore 73401, Oklahoma, USA
³Biotechnology Program, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand

Article history:
Received January 15, 2010
Accepted June 16, 2010

Keywords:
Pithecellobium dulce, seed protein, lysozyme, antifungal activity

Summary:
A protein of an apparent molecular mass of 14.4 kDa with antifungal activity was isolated from the seeds of Pithecellobium dulce using extraction with 100 mM Tris-HCl buffer (pH=8.0), precipitation with 80 % ammonium sulfate, and bioassay purification via Resource Q anion exchange chromatography and Superdex 200 gel filtration chromatography. The purified protein was putatively identified by tandem mass spectrometry with Mascot database searching, with the partial amino acid sequences showing a high degree of similarity to chicken egg white lysozyme. This putative plant lysozyme expressed antifungal activity with a rather high thermal stability of up to 80 °C for 15 min (at pH=8.0). It exerted an antifungal action towards Macrophomina phaseolina but displayed no antifungal activity against two other isolates, Phymatotrichopsis omnivora and Fusarium avenaceum.

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