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

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 15,973.0Da 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±0.44mm and 16.5±1.15mm, respectively. The IC₅₀ of inhibition rate for PGC on NO production was 9.60±0.71μg/mL. Therefore, PGC might be developed as one of potential antibacterial and anti-inflammatory agents.