Detection of native peptides from Channa striata extract using de novo sequencing

Abstract

Channa striata or Snakehead fish is well-known as medicinal fish in Asian countries, including Indonesia. It is rich in functional amino acid as well as high protein. Previous study showed the fish extract was active as an ACE inhibitor in vitro, in which 5-10 kDa fraction of 50% ethanol extract has the potential ACE inhibitory activity (4,76% inhibition of ACE g-1 protein). This study aims to identify the native peptide in the Channa striata extract using LS-MS/MS. The 5-10 kDa extract fraction was further purified using Sephadex G-50, the significant peak fraction was treated with trypsin and untreated before being analysed using LC-MS/MS. The result showed that the untreated fraction had better result than trypsin treated one, indicating the significant peak fraction contains native peptide. We identified the presence of a 25.8 kDa β-actin fragment using the Channa striata database and two peptides GQVITIGNER and VITIGNER that meet the requirement software Proteome Discoverer 2.1. De Novo sequencing resulted 319 peptides with ALC >70%. Bioinformatics study revealed that the native peptide resulting from de novo sequencing was rich in inhibitor ACE peptides. These concluded that Channa striata contain a native peptide that is potentially an ACE inhibitor or anti-hypertension.