Purification and characterization of an antibacterial and anti-inflammatory polypeptide from Arca subcrenata

- A polypeptide (PGC) was isolated from Arca subcrenata muscle.
- The isoelectric point of PGC was determined to be 9.76. The molecular weight was determined to be 15973.0 Da by ESI-MS/MS.
- N terminal amino acid sequence of PGC was shown as PSVYDAAAQLTADVKKDLRDSWKVIGGDKKGNGVA by Edman degradation.
- The diameter of the inhibitory ring of PGC on E.coli and S. aureus were 14.5 ± 0.44 mm and 16.5 ± 1.15 mm, respectively.
- The in vitro assay results indicated that the IC50 of inhibition rate for PGC on NO production was 9.60 ± 0.71 μg/mL.

A polypeptide coded as PGC was isolated from Arca subcrenata muscle using ion exchange, Sephadex G-50 gel chromatography and RP-HPLC. PGC was identified to be a homogeneous compound by Native-PAGE and the purity was more than 98.9% measured by HPLC. The isoelectric point of PGC was determined to be 9.76 by IEF-PAGE. The molecular weight was determined to be 15,973.0 Da by ESI-MS/MS. The conformational structure of PGC was characterized by UV-vis, FT-IR and CD spectroscopy. N terminal amino acid sequence of PGC was shown as PSVYDAAAQLTADVKKDLRDSWKVIGGDKKGNGVA by Edman degradation. The results demonstrated that there is a high degree of homology between PGC and the subunit from hemoglobin, and proposed that PGC is the depolymerized polypeptide of Hemoglobin I (HbI) from A. subcrenata. The evaluation of biological activities showed that the diameters of the inhibitory ring of PGC on Escherichia coli and Staphylococcus aureus were 14.5 ± 0.44 mm and 16.5 ± 1.15 mm, respectively. The IC50 of inhibition rate for PGC on NO production was 9.60 ± 0.71 μg/mL. Therefore, PGC might be developed as one of potential antibacterial and anti-inflammatory agents.

138