59D-7 |
Angiotensin I-converting enzyme inhibitory peptides from hydrolysed bovine plasma proteins |
P. J. SHAND1, J. Wanasundara1, R. Amarowicz2, and R. B. Pegg3. (1) Dept. of Applied Microbiology & Food Science, Univ. of Saskatchewan, 51 Campus Dr., Saskatoon, SK S7N 5A8, Canada, (2) Division of Food Science, Institute of Animal Reproduction and Food Research of Polish Academy of Science, ul. Tuwima 10, P.O.Box 55, 10-718, Olsztyn 5, Poland, (3) Department of Applied Microbiology and Food Science, University of Saskatchewan, 51 Campus Drive, Saskatoon, SK S7N 5A8, Canada Among the biologically active peptides, anti-hypertensive peptides have a special role in the development of physiologically-functional foods. Angiotensin I-converting enzyme (ACE, peptidyl-dipeptidase A, EC.3.4.15.1) elevates blood pressure by catalysing the conversion of inactive Angiotensin I to the potent vasoconstrictor Angiotensin II. Therefore, inhibitors of ACE play an important role in controlling hypertension. Some food-derived peptides have exhibited strong ACE inhibitory activity in-vitro and in animal models. This study was carried out to investigate the ACE inhibitory activity of peptides obtained from hydrolysis of bovine blood plasma protein and to identify these active peptides. Bovine blood plasma proteins (BPP) were hydrolysed with Flavourzyme LTM to achieve a high degree of hydrolysis up to 48%. Inhibitory activity of the hydrolysate and its size exclusion fractions against porcine kidney ACE was determined as in-vitro release of hippuric acid from hippuryl-L-histidyl-L-leucine. The content of free hippuric acid was determined by HPLC. Peptides of high-inhibitory active fractions were separated and sequenced via MALDI-TOF-MS and MS-MS. Unhydrolysed BPP has negligible amount of ACE inhibitory activity. As the degree of hydrolysis (DH) increased, ACE inhibitory activity of the hydrolysed plasma did as well. At 48% DH, 79% inhibition of ACE activity was observed. The inhibitory activity was concentration dependant but appeared to be a non-competitive type inhibition. An IC50 value of 0.7 mg/ml was obtained for 48% DH BPP. Peptides from the 48% DH sample with molecular weights less than 30 kDa had two high-inhibitory fractions. The most abundant fraction contained one active peak corresponding to be peptides. Further characterization of this active peptide peak via mass spectroscopy revealed that it consists of tri- and tetra-peptides. The observed Angiotensin-I inhibitory activity of hydrolysed plasma proteins may be of value in the development of antihypertensive foods or food ingredients.
Session 59D, Food Chemistry: Proteins and Physicochemical Properties
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