Study on the Preparation of Andiotensin-converting Enzyme Inhibitors (ACE I) from Hydrolysates of Gelation and Whey Protein

• Main Authors: Koh, Siew Ken, 許秀娟
• Other Authors: Hung-Min Chang
• Format: Others
• Language: zh-TW
• Published: 1997
• Online Access: http://ndltd.ncl.edu.tw/handle/64282504208542583434

碩士 === 國立臺灣大學 === 食品科技研究所 === 85 === 1% gelatin solution was hydrolyzed with esperase (E/S=1/20) at 60℃in 0.1M pho sphate buffer (pH 8.0) for various periods of time, measuring the degree of hy drolysis and ACE ( angiotensin- converting enzyme , ACE) inhibitory percentage of the hydrolysates . The result showed that there was an abrupt increase in the degree of hydrolysis, i. e. from 0.0% to 8.0%, within the first two hour o f hydrolysis；meanwhile the ACE inhibitory percentage of the hydrolysates had increased form 3.4% to 26.7%. There was an increase in the degree of hydrolysi s beyond 2 hours of reacting time, yet the hydrolysates did not show parallel increase in their respective ACE inhibitory percentage. Gelatin hydrolysate ha d reached its maximum ACE inhibitory percentage at 2 hour of hydrolysis, at wh ich its IC50 value was 11.6mg/ml and the gelatin hydrolysate collected at this point of time was designated as G2.Sephacryl S-200 column chromatography of G 2 revealed 2 peaks, designated as G2-1 and G2-2, whose apparent molecular weig ht lies in the range of 12,900 and 87,000, respectively. The IC50 of G2-1 and G2-2 was determined as 8.1mg/ml and 1.1mg/ml, respectively, indicating that th ere was a progress in the ACE inhibitory ability of the hydrolysate after isol ation.1% whey protein solution was hydrolyzed with esperase (E/S=1/20) at 60℃ in 0.1M phosphate buffer (pH 8.0) for various periods of time, measuring the d egree of hydrolysis and ACE inhibitory percentage of the hydrolysates . The re sult also showed a dramatic increase both in the degree of hydrolysis and ACE inhibitory percentage of the hydrolysate within the first two hours of reactio n. The degree of hydrolysis of whey protein had increased from 0.0% to 8.5% wi thin the first two hours and reached its plateau after 18 hour of hydrolysis, at which the degree of hydrolysis was about 12.6%. The ACE inhibitory percenta ge of the hydrolysate had markedly increased after 2 hour of hydrolysis, i. e. from 57.0% to 77.4%, attaining its maximum ACE inhibitory ability at IC50 val ue of 1.0mg/ml after 14 hour of hydrolysis, and the degree of hydrolyisis of t he hydrolysate (A14) collected at this point was 11.7%. The result also indica ted that whey protein hydrolysates show better ACE inhibitory ability than gel atin hydrolysates did.Sephacryl S-200 column chromatography of A14 revealed 2 peaks, designated as A14-1 and A14-2, whose apparent molecular weight lied in the range of 43,700 and 2,300, respectively. The IC50 value of A14-1 and A14-2 was determined as 0.8mg/ml and 3.0mg/ml, respectively.Amino acid analysis of A14, A14-1, A14-2, G2, G2-1 and G2-2 revealed that A14-1contains greater amoun t of aromatic, basic and hydrophobic acid as compared to A14-2, G2, G2-1 and G 2-2, while approximately to that of A14. A14-1contains 22% of hydrophobic amin o acid, 14.8% of basic amino acid and 8.9% of aromatic amino acid. As Cheung e t al.(1980) suggested that potent ACE I peptide may contain aromatic amino aci d at its C-terminal, basic or hydrophobic amino acid at its N-terminal, we spe culated that the potent peptide in A14-1 may probably possess similar characte ristic.