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Purification of a Novel Angiotensin I-Converting Enzyme (ACE) Inhibitory Peptide with an Antihypertensive Effect from Loach (Misgurnus anguillicaudatus)
- Li, Ying, Zhou, Jianzhong, Huang, Kaihong, Sun, Yi, Zeng, Xiaoxiong
- Journal of agricultural and food chemistry 2012 v.60 no.5 pp. 1320-1325
- Misgurnus anguillicaudatus, antihypertensive effect, enzyme inhibitors, high performance liquid chromatography, hydrolysates, inhibitory concentration 50, mass spectrometry, oral administration, papain, pepsin, peptidyl-dipeptidase A, rats, size exclusion chromatography, subtilisin, systolic blood pressure, ultrafiltration
- To isolate and characterize novel angiotensin I-converting enzyme (ACE) inhibitory peptide from loach (Misgurnus anguillicaudatus), six proteases, pepsin, α-chymotrypsin, bromelain, papain, alcalase, and Neutrase, were used to hydrolyze loach protein. The hydrolysate (LPH) generated by bromelain [ratio of enzyme to substrate, 3:1000 (w/w)] was found to have the highest ACE inhibitory activity (IC₅₀, 613.2 ± 8.3 μg/mL). Therefore, it was treated by ultrafiltration to afford fraction of LPH-IV (MW < 2.5 kDa) with an IC₅₀ of 231.2 ± 3.8 μg/mL, having higher activity than the other fractions. Then, LPH-IV was isolated and purified by consecutive purification steps of gel filtration chromatography and reverse-phase high-performance liquid chromatography to afford a purified peptide with an IC₅₀ of 18.2 ± 0.9 μg/mL, an increase of 33.7-fold in ACE inhibitory activity as compared with that of LPH. The purified peptide was identified as Ala-His-Leu-Leu (452 Da) by Q-TOF mass spectrometry and amino acid analyzer. An antihypertensive effect in spontaneously hypertensive rats revealed that oral administration of LPH-IV could decrease systolic blood pressure significantly.