Chemical and mass spectrometry characterization of the red alga Pyropia yezoensis chemoprotective protein (PYP): protective activity of the N-terminal fragment of PYP1 against acetaminophen-induced cell death in Chang liver cells.

In the present study, the chemical structure and chemoprotective activity of Pyropia yezoensis protein (PYP) were investigated using sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis, automated protein sequencing, matrix-assisted laser desorption/ionization-quadrupole ion trap-time-of-flight mass spectrometry and a chemoprotective assay using a synthetic peptide. The PYP fraction was demonstrated to contain two proteins: PYP1 (10 kDa, SDS-resistant dimer) and PYP2 (10 kDa). PYP1 is a novel protein showing sequence homology with the hypothetical function-unknown proteins of Chondrus crispus (Rhodophyta) and Emiliania huxleyi (Haptophyceae). PYP2 is a paralog of an extrinsic protein of photosystem II found in other Rhodophyta. The synthetic peptide PYP1 (1-20), corresponding to the N-terminal 20 residues of PYP1 (ALEGGKSSGGGEATRDPEPT), exhibits chemoprotective activity against acetaminophen-induced cell death in Chang liver cells, indicating that PYP1 is a chemoprotectant of the PYP fraction. A possible association between the structure of PYP and its chemoprotective activity is discussed.