Recombinant production of a bioactive peptide from spotless smooth-hound (Mustelus griseus) muscle and characterization of its antioxidant activity.

Bioactive peptides are short amino acid sequences with desirable health effects which are derived from animals, plants, and marine sources. In this study, recombinant production of a bioactive peptide (GIISHR) from spotless smooth-hound (Mustelus griseus) muscle and its antioxidant properties is discussed. A gene composed of 12 tandem copies of the peptide sequence was cloned in pET-28a and expressed as a His-tagged polypeptide in Escherichia coli. The recombinant polypeptide was then purified by Ni-NTA affinity chromatography, cleaved by Trypsin and purified by ultrafiltration. DPPH (1,1-diphenyl-2-picrylhydrazyl), ABTS (2,2'-azinobis-3-ethylbenzotiazoline-6-sulfonic acid) and hydroxyl radical scavenging activity assays, ferric reducing antioxidant power (FRAP) assay and β-carotene bleaching test were used to characterize the antioxidant activity of the GIISHR. Liquid chromatography-mass spectrometry analysis revealed 60% purity for released bioactive peptide. Production yield was estimated as 60-80 mg GIISHR active peptide per 1 L bacterial culture. Antioxidant activity assays indicated that the antioxidant activity was increased with increase in peptide concentration. Though the DPPH radical scavenging activity, FRAP and β-carotene bleaching power of the peptide were lower than those of the synthetic antioxidant tert-butylhydroquinone (TBHQ), the ABTS and hydroxyl radical scavenging activities of the peptide (at a concentration of 20 mg/mL) were similar to those of TBHQ (at a concentration of 0.1 mg/mL). The findings of the present study may be helpful in development of a process for production of the bioactive antioxidant peptides and its application in food industry.