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.

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