Purification and characterisation of an inhibitor of a cathepsin B-like proteinase from sunflower seed

Abstract

Cathepsin B is a vitally important enzyme in various physiological processes and in tumor invasion and metastasis. A cathepsin B inhibitor, HCB-SunI, was identified and purified from sunflower seeds, Helianthus annuus, using ammonium sulfate precipitation and two steps of conventional chromatography. The molecular mass of HCB-SunI was estimated to be 12 kDa by SDS-PAGE and 12.32 kDa by MALDI TOF MS. Its N-terminal amino acid sequence was determined to be: PYGGGGTESG. HCB-SunI not only inhibited Helicoverpa cathepsin B (HCB) but also decreased the growth of HeLa and glioma cells by 7 ∼ 27% and 6 ∼ 22%, respectively, when the cells were grown in a final concentration of 0.002 ∼ 0.008 μM inhibitor.

Keywords::

• Helianthus annuus
• Cathepsin B
• Inhibitor
• Purification
• Tumor cells effect
• sunflower seed

Acknowledgement

This work was supported by National Natural Science Foundation of China (No: 30330070) and the Natural Science Foundation of Shandong Province (No. Z2003D04). The authors thank Dr. Roberta Greenwood for her editing.