Production of angiotensin I converting enzyme inhibitory peptides from sea bream scales

Tests were conducted to evaluate the inhibitory effects of collagen peptides in the hydrolysate of sea bream scales on the activity of angiotensin I converting enzyme (ACE, EC3.4.15.1). The scales were hydrolyzed using an alkaline protease treatment by which 92% of the peptides were degraded to form hydrolysate. The 50% inhibitory concentration of the peptides was as high as 0.57 mg ml(-1). In addition, using spontaneously hypertensive rats, oral administration of 300 mg of the peptides (kg of body weight)(-1) d(-1) was shown to decrease blood pressure significantly (P<0.05). Four peptides that demonstrated high ACE inhibitory activities were isolated from the hydrolysate of the scales using chromatographic methods. The ACE inhibitory activities of the isolated peptides were 5-20 times higher than that of the unpurified hydrolysate. The amino acid sequences of inhibitory peptides were determined to be Gly-Tyr, Val-Tyr, Gly-Phe and Val-Ile-Tyr. (C) 2003 Elsevier Ltd. All rights reserved.