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Preparation of Corn Peptide in Nonaqueous Media and Its Antialcoholism Activity in Vitro

Author: LiLiLi
Tutor: WuZuo
School: South China University of Technology
Course: Food Quality and Safety
Keywords: nonaqueous phase corn peptide immobilized Alcalase antialcoholic activity
CLC: TQ464.7
Type: Master's thesis
Year: 2011
Downloads: 145
Quote: 1
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Abstract


According to researches at home and abroad, the zein hydrolysate has a good antialcoholic activity. In this study, based on the peculiarities of corn protein hydrolysate, such as molecular weight, distribution of molecular weight, amino acid composition and so on, gel chromatography and reversed-phase high performance liquid chromatography (RP-HPLC) were utilized to separate and purify the peptides. Then the antialcoholic activities of the separated products were analyzed by determining antialcoholic activities of alcohol dehydrogenase (ADH) and Aldehyde Dehydrogenase (ALDH) to explore the correlation between different components of corn protein hydrolysate and their antialcoholic activities from various points of view. It is not only significant to illustrate antialcoholic mechanism of corn peptides, but also of the practical significant for promoting the application of corn proteins.The preparation of immobilized proteinase for corn protein hydrolysis was investigated at first. The results showed that the optimal conditions for immobilizing Alcalase were sodium alginate concentration 3%(w/v), Alcalase concentration 2%(v/v), and CaCl2 concentration 2%(w/v). The immobilized proteinase was then used for hydrolysis of corn protein. And the optimum hydrolysis conditions were determined as follows: tertiary butyl alcohol—water system (1:1,v/v), substrate concentration 5% (W/V), dosage of immobilized Alcalase 8%(W/V), pH 8.5, temperature 55℃and hydrolysis time 2.5h. Under these conditions, the hydyolysis degree reached 22.7%. After being used for 3 times repeatedly, more than 50% activity of immobilized Alcalase remains. The immobilized Alcalase protease when stored at 4℃for 10 days, and showed high activity more than 60%.Secondly, indexes of corn protein hydrolysates are determined. The results showed that the contents of peptide, sugary compounds content, fat and ash were 80.2%, 1.2%, 0.4% and 10.5%, respectively. The molecular weight of nonaqueous enzymatic hydrolysate was less than 3548Da, of which molecular weight less than 1295 Da peptides were the most abundant, accounting for about 80%, mostly 2 to 10 peptides. Analysis of amino acid composition of corn protein hydrolysates showed that preparation of corn peptide in nonaqueous phase contained the active peptide in a higher proportion of alanine (9.2mol%), leucine (17.05 mol%) and proline (8.83 mol%). Comparison of the hydrolysates in aqueous and nonaqueous media with the same DH showed that the content of Ala, Leu, and Pro in hydrolysates prepared in the nonaqueous phase was higher than that of in hydrolysates prepared in the aqueous phase by 1.02 mol%, 3.18 mol% and 1.39 mol%, respectively. Then a gel chromatography and reversed-phase high performance liquid chromatography (RP-HPLC) were utilized to separate and purify the peptides and then determined alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) activities in vitro. Sephedax G-15 gel chromatography, DEAE-Sephrose anion-exchange chromatography, Sephedax G-10 gel chromatography were used to seperate samples and then determined the ratio of alcohol dehydrogenase(ADH), results showed that the highest antialcoholic activation rate of nonaqueous phase was 35.73%, the highest antialcoholic activation rate of aqueous phase was 27.12%, the highest antialcoholic activation rate of commercially available peptide was 11.33 %.After separated and analysed by LC/MS method, the mass-to-charge ratio(m/z) of the peptide with high antialcoholic activation was 616.8, analysis of amino acid composition of corn peptide purified by gel chromatography showed that there are mainly about six amino acids, the molar ratio is n (Glu): n (Ala): n (Pro): n (Tyr ): n (L eu): n (Phe)≈1:1:1:1:2:1.

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CLC: > Industrial Technology > Chemical Industry > Pharmaceutical chemical industry > Drug production of biological products > Amino acids,peptides,proteins
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