Purification and Identification of Novel Xanthine Oxidase Inhibitory Peptides Derived from Round Scad (Decapterus maruadsi) Protein Hydrolysates.

Xiao Hu,Shengjun Chen,Yanyan Wu,Ya Zhou,Laihao Li,Shaobo Zhou,Xianqing Yang

doi:10.3390/md19100538

Abstract

The objective of the present study was to investigate the xanthine oxidase (XO) inhibitory effects of peptides purified and identified from round scad (Decapterus maruadsi) hydrolysates (RSHs). In this study, RSHs were obtained by using three proteases (neutrase, protamex and alcalase). Among them, the RSHs of 6-h hydrolysis by neutrase displayed the strongest XO inhibitory activity and had an abundance of small peptides (<500 Da). Four novel peptides were purified by immobilized metal affinity chromatography and identified by nano-high-performance liquid chromatography mass/mass spectrometry. Their amino acid sequences were KGFP (447.53 Da), FPSV (448.51 Da), FPFP (506.59 Da) and WPDGR (629.66 Da), respectively. Then the peptides were synthesized to evaluate their XO inhibitory activity. The results indicated that the peptides of both FPSV (5 mM) and FPFP (5 mM) exhibited higher XO inhibitory activity (22.61 ± 1.81% and 20.09 ± 2.41% respectively). Fluorescence spectra assay demonstrated that the fluorescence quenching mechanism of XO by these inhibitors (FPSV and FPFP) was a static quenching procedure. The study of inhibition kinetics suggested that the inhibition of both FPSV and FPFP was reversible, and the type of their inhibition was a mixed one. Molecular docking revealed the importance of π-π stacking between Phe residue (contained in peptides) and Phe914 (contained in the XO) in the XO inhibitory activity of the peptides.

Highlights

Hyperuricemia is currently recognized as the fourth highest-risk chronic disease after hyperglycemia, hypertension, and hyperlipidemia, which could cause complications such as gout, hypertension and diabetes disease [1]
The xanthine oxidase (XO) inhibitory activity of the neutrase hydrolysates was dramatically increased with the increase of hydrolysis time (1–6 h)
The XO inhibitory activity showed a small decrease when the hydrolysis time was over 6 h, which indicated that excessive hydrolysis was not conducive to the hydrolysate to exhibit high XO inhibitory activity

Summary

Introduction

Hyperuricemia is currently recognized as the fourth highest-risk chronic disease after hyperglycemia, hypertension, and hyperlipidemia, which could cause complications such as gout, hypertension and diabetes disease [1]. It is a metabolic disease mainly caused by the production of excess uric acid or uric acid excretion disorder in the body [2]. Excessive uric acid may lead to the sedimentation of urate crystals in joints and gout. XO is a homodimer with a molecular mass of approximately 290 kDa [5]. Each monomer of XO contains one N-terminal domain (20 kDa) including two iron–sulfur centers

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Results

Conclusion