Effect of angiotensin I converting enzyme inhibitory peptide purified from skate skin hydrolysate

Our objective was to evaluate the angiotensin I converting enzyme (ACE) inhibitory activity of skate skin protein hydrolysates and its corresponding fractions. The skate skin hydrolysates were obtained by enzymatic hydrolysis using alcalase, alpha-chymotrypsin, neutrase, pepsin, papain, and trypsin. Amongst the six hydrolysates, the alpha-chymotrypsin hydrolysate had the highest ACE inhibitory activity compared to other hydrolysates. The amino acid sequences of the purified peptides were identified to be Pro-Gly-Pro-Leu-Gly-Leu-Thr-Gly-Pro (975.38 Da), and Gln-Leu-Gly-Phe-Leu-Gly-Pro-Arg (874.45 Da). The purified peptides from skate skin had an IC50 value of 95 mu M and 148 mu M, respectively, and the Lineweaver-Burk plots suggest that they act as a non-competitive inhibitor against ACE. Our study suggested that novel ACE inhibitory peptides derived from skate skin protein may be beneficial as anti-hypertension compounds in functional foods. (C) 2010 Elsevier Ltd All rights reserved.