Preparation Of Mungbean Protein Hydrolysate And Its Protective Effect On Oxidative Damage Of NCTC1469 Cells

Mung bean protein is a plant-derived protein,riches in amino acid composition,and is a raw material for enzymatic hydrolysis of peptides.In recent years,it has been reported that the hydrolysate has many biological activities,and it is easily digestible and not easily saturated in vivo.In this paper,mungbean were used as raw materials to obtain high-quality protein by optimizing protein extraction conditions.Then,controlled-hydrolysis technology was used to prepare anti-oxidation active proteolysates.Subsequent separation and purification of proteolysates with different molecular weights was performed.Finally,the study was conducted on H₂O₂.Induced protection of oxidative damage in NCTC1469 cells.The main research contents and results are as follows:1.The alkaline extraction and acid precipitation method was used to extract the protein of mung bean and optimize the process.The optimal extraction conditions were obtained as follows:the ratio of material to liquid was 1:20 g/mL,the pH of alkaline extract was 9 and the extraction temperature was 40°C.The total protein extraction rate was 73.25%.2.The solubility of mung bean protein was greatly affected by pH,and the total protein and albumin isoelectric points were around pH 4.6 and 4.5,respectively,with the lowest solubility.The greater the degree of deviation from the isoelectric point,the stronger the solubility of the protein.The total protein and albumin solubility were the highest at pH 6.5 and 6.7,respectively.The water holding capacity of mung bean protein is normal,the oil absorption performance is obvious,the emulsifying property is high,but the emulsion stability is poor.The secondary structure of mung bean protein mainly consists of?-helix and?-sheet.The amino acids of the protein are diverse and rich in content.Among the chemical scores of essential amino acids,only proline is lower than the recommended value,and it is called"in cereals."The lysine of the first limiting amino acid"had a chemical score of 140.7%and 123.3%,respectively,in total protein and albumin.3.Alkaline protease is the most suitable enzyme for the preparation of mung bean antioxidant peptides.Mung bean protein?MBP?was hydrolyzed by papain,alkaline protease,neutral protease and trypsin,and the alcalase hydrolysate presented better degree of hydrolysis?DH?and Trichloroacetic acid-nitrogen soluble index?TCA-NSI?than other hydrolysates and was selected for further study.4.The mung bean protein hydrolysates?MBPHs?were ultra-filtered into three fractions:MBPHs-I?<3 kDa?,MBPHs-II?3-10 kDa?and MBPH-III?>10 kDa?.MBPHs and fractionates were tested for secondary structure determination,amino acid composition and antioxidant activity.No significant difference had been found in fourier transform infrared?FTIR?and CD spectroscopy of MBPHs and their three components,showing that ultrafiltration didn't change the secondary structure of enzymatic hydrolysate,which mainly contained?-helix,?-sheet and irregular coiled,and the beta angle structure of proteins may be destroyed by enzymatic hydrolysis.MBPH-I?<3 kDa?fraction contained higher hydrophobic?38.317 g/100 g?and aromatic amino acids?10.566 g/100 g?when compared to other fractions and also exhibited the strongest radical scavenging.5.The effect of mung bean protein hydrolysates on cell viability was determined by CCK-8 method.The appropriate concentration and induction time of H₂O₂ were determined and the oxidative damage model of NCTC 1469 cells was established.After the addition of MBPHs,MBPHs-I,MPBHs-II,and MPBHs-III,the viability of NCTC 1469 cells increased to varying degrees,in which the protective effect of MPBHs-I on the survival rate of NCTC 1469 cell induced by H₂O₂ was significantly higher than that of other mung bean protein hydrolysates.Its effect on the contents of MDA and GSH,and the activities of SOD and LDH in NCTC 1469 cells was determined.The results showed that mung bean peptides could protect the oxidative enzymes in NCTC 1469 cells,protect the oxidative damage of NCTC 1469 cells and increase the cell viability.