Effect of different buffer systems on the xanthine oxidase inhibitory activity of tuna (Katsuwonus pelamis) protein hydrolysate

Authors：Su Guowan; He Weiwei; Zhao Mouming; Waterhouse Geoffrey I. N.; Sun-Waterhouse Dongxiao^*

Source：Food Research International, 2018, 105: 556-562.

DOI：10.1016/j.foodres.2017.11.037

• Tuna protein hydrolysate
• HEPES
• Xanthine oxidase
• Inhibition
• Interaction
• Secondary structure

This study systematically explored the effect of HEPES, Tris and sodium phosphate (PB) buffers on the xanthine oxidase (XO) inhibitory activity of tuna protein hydrolysate (TPH, containing over 90% of constituents with molecular weight below 5 kDa). The greatest XO inhibition by TPH was observed in HEPES buffer. The optimal HEPES concentration was 100 mmol/L. Tryptophan fluorescence and circular dichroism measurements revealed the comparable stability of XO and TPH in the three buffers. The buffers did not alter the majority of XO or TPH structure but induced slight modifications to specific domains (e.g. Trp residues on alpha-helices) and certain re-arrangements (e.g. XO unfolding or refolding). HEPES buffer exerted stronger interactions with XO or TPH, causing a lower alpha-helical content in XO and consequently a lower XO catalytic activity but greater XO inhibition, compared to Tris and PB buffers.

• Institution
  华南理工大学