High Fischer Ratio Research Articles

HEPATOPROTECTIVE EFFECTS OF CORN PEPTIDES AGAINST CARBON TETRACHLORIDE-INDUCED LIVER INJURY IN MICE

ABSTRACT Hepatic injury is a prevalent ailment worldwide. The hepatoprotective effects of corn peptides (CPs) were evaluated against carbon tetrachloride (CCl4)-induced liver injury in mice. Low molecular weight CP (Mw < 5 kD) were obtained by alcalase hydrolysis combined with ultrafiltration technology. Results showed that the hepatoprotective effects of CP (200 mg/kg body weight [bw]) were manifested by a significant decrease of the aminotransferase (aspartate transaminase, alanine transaminase) activities in serum and malondialdehyde level in liver, and by a significant increase of superoxide dismutase activity and glutathione level in liver (P < 0.01), compared with the model group. The biochemical findings were supplemented by histopathological examination of liver sections. The hepatoprotective effect was close to that of positive control group – Silymarin (50 mg/kg bw). In conclusion, this study demonstrated that the pretreatment of CP at the dose of 200 mg/kg bw showed a significant protective effect to alleviate CCl4-induced hepatocellular injury, and the hepatoprotective effect was due to the CP's antioxidant capability and high Fischer's ratio. PRACTICAL APPLICATIONS There is an ever-increasing need of an agent that could protect liver from various damages. Therapies developed along the principles of Western medicine are often limited in efficacy, carry the risk of adverse effects and are often too costly, especially for the developing world. Corn peptides (CPs) were obtained from corn gluten meal, which was the by-product of corn industry. It will broaden the application and increase the value of corn gluten meal. CPs, especially those with low molecular weight, have been reported with many bioactive functions, which were isolated with potent free radical scavenging capacities and high Fischer's ratio. In general CP could become a safe and potent hepatoprotective agent and could be manufactured into various forms, such as powder, tinctures, tablet, capsule and syrup. The future applications of CP would be mostly as a medicine, supplement or functional foods.

Preparation of Oligopeptide Mixture with a High Fischer Ratio from Egg White Proteins

Oligopeptide with a high Fischer ratio by protease hydrolysis from egg white was prepared. The optimal substrate concentration 5.5% and denatured time 15min were determined by nitrogen recovery ratio (NR) testing. Alcalase and enzymesⅡ were selected to hydrolyze egg white protein. The performance of ion exchange resin was chosen when flow rate of the hydrolysate was 8vol/hr. The NR of the hydrolysate was 84.01% and the desalinization ratio was 81.73% after passing ion exchange resin. Activated carbon adsorption chromatography was used to remove free AAA and the result of UV-scanning indicated that active carbon was efficient to absorb AAA. The composition analyzed results showed that the Fischer ratio of hydrolysate was 20.46 and the content of free amino acid was 8.04％. The G-25 gel filration chromatography was used to determine the molecular weight (MW) of hydrolysate and the results showed that the MW distribution of the hydrolysate with a high Fischer ratio was consecutive and it ranged from 300 to 600.

Antioxidant and Angiotensin Converting Enzyme-Inhibitory Properties of a Flaxseed Protein-Derived High Fischer Ratio Peptide Mixture

Hydrolysis of flaxseed proteins using thermolysin and pronase followed by mixing with activated carbon, centrifugation and filtration yielded a filtrate (peptide mixture) with a Fischer ratio (branched-chain amino acids/aromatic amino acids) of 23.65 and a phenylalanine + tyrosine content of 1.11%. Gel permeation chromatography showed that the flaxseed peptide sample contained mainly low molecular weight peptides (<4 kDa). The high Fischer ratio peptide sample exhibited antioxidant property by scavenging 2,2-diphenyl-1-picrylhydrazyl radical, superoxide radical, hydroxyl radical, and also by protecting linoleic acid from oxidation. In addition, the peptide mixture showed potential antihypertensive properties by inhibiting angiotensin I-converting enzyme in a mixed-type inhibition pattern. Protein hydrolysates with Fischer ratio higher than 20 and phenylalanine + tyrosine content lower than 2% have been used to treat patients with hepatic encephalopathy; thus, this multifunctional flaxseed peptide mixture could be used to formulate food products with multiple human health benefits during liver diseases, oxidative stress and hypertension.

Preparation and characterisation of the pearl oyster (Pinctada martensii) meat protein hydrolysates with a high Fischer ratio

SummaryThe primary aim of this study was to obtain high Fischer ratio oligopeptides from the pearl oyster Pinctada martensii meat via proteolysis. Pinctada martensii meat protein was hydrolysed using seven proteases, with pancreatin showing the most protein recovered (90.30%) and the highest degree of hydrolysis (30.22%). In addition, pancreatin treatment liberated aromatic amino acids (AAA) and preserved branched‐chain amino acids (BCAA) in the peptide chain more efficiently than other proteases. In our enzymatic hydrolysis system, the AAA are adsorbed by activated carbon much easier in the form of proteins and peptides compared with the free state. The fraction purified from the pancreatin hydrolysate after adsorption onto activated carbon gave a yield of 38.42% based on nitrogen content. It was composed primarily of low molecular weight peptides and had a Fischer ratio of 24.58, with phenylalanine (Phe) and tyrosine (Tyr) content below 1.2%. This oligopeptide mixture can be used for the assistance treatment of patients with hepatic encephalopathy, phenylketonuria and tyrosinemia according to different dietetic requirement.

Preparation of high Fischer ratio oligopeptide by proteolysis of corn gluten meal

A method to obtain an oligopeptide with high Fischer ratio is described. Corn gluten meal (CGM) was hydrolysed with Alcalase 2.4L using a two-step hydrolysis. In the first-step hydrolysis, the enzyme reaction conditions for hydrolysing CGM were optimised by using the orthogonal experimental design, while pH = 8.0, temperature = 55°C, enzyme to substrate ratio (3:97, w/w), and the substrate concentration = 5% were identified as the optimum conditions, under which up to 11.62% degree of hydrolysis (DH) could be obtained. The hydrolysate was then fractionated by ultrafiltration using a membrane with the molecular cutoff of over 10 kD at 20 kPa. For the second-step hydrolysis, the filtrate was adjusted to pH 6.0, then papain was added at 50°C and the mixture was maintained for 3 hours. The hydrolysate was obtained after inactivating papain and centrifuging. Then the salt (mainly NaCl) in the hydrolysate was removed with an ion exchange resin at the speed of 8 times bed volume per hour, and aromatic amino acids were removed through absorption by active carbon. By using Sephadex G-25 gel filtration chromatography, a peptide mixture with low molecular weights between 1000 and 1300 was obtained. Finally, tests on amino acid composition and free amino acid concentration of oligopeptide solution showed that the oligopeptide had a high Fischer ratio of 34.71 and the yield of 11.59%.

Production of Brassica carinata Protein Hydrolyzates with a High Fischer's Ratio Using Immobilized Proteases

Brassica carinata protein isolates were hydrolyzed using the digestive enzymes trypsin, chymotrypsin, and carboxypeptidase A in order to obtain hydrolyzates with a high Fischer's ratio. The proteases were immobilized using two glyoxyl-agarose supports of different porosity, 4 and 10% agarose gels, in order to evaluate the effect of substrate diffusion into the support containing the enzyme on the hydrolytic process. Reaction time, substrate concentration, and the enzyme to substrate ratio were optimized in an attempt to increase the Fischer's ratio in the resulting hydrolyzates. Gel filtration chromatography of a hydrolyzate with a degree of hydrolysis of 36% yielded a fraction that represented 31% of the total hydrolyzed proteins and had a Fischer's ratio of 28.3 with a phenylalanine + tyrosine content below 1.5%. This material could be used for preparing special diets when there is a need to increase the supply of branched amino acids and/or reduce the intake of aromatic amino acids.

Production and characterization of casein hydrolysates with a high amino acid Fischer's ratio using immobilized proteases

Abstract A procedure using immobilized enzymes has been developed to obtain protein hydrolysates with a high Fischer's ratio (branched-chain amino acids/aromatic amino acids (AAA)) from bovine casein. Pre-digestion with trypsin was followed by treatment with chymotrypsin, which generated a hydrolysate enriched in peptides with AAA at the carboxyl end. Carboxypeptidase A was then used to remove these AAA. A fraction, which represents 24% of total hydrolyzed proteins, with a Fischer's ratio of 30.6, and Phe+Tyr content below 1.4% of the total, was purified from this hydrolysate by gel filtration in a Biogel P2 column. This material could be used for the treatment of patients suffering from certain hepatic encephalophaties, tyrosinemia and phenylketonuria.

Sunflower protein hydrolysates for dietary treatment of patients with liver failure

AbstractA method is described to obtain hydrolysates with defined characteristics and a high Fischer ratio for patients with liver failure, using sunflower proteins (globulin fraction‐II) as starting material. Protein with a branched chain amino acid (BCAA) concentration of 29.7±1.7% is treated in a first step with immobilized chymotrypsin (raw hydrolysate‐1). Subsequent ultrafiltration (cut‐off 3 kDa) of the hydrolysate gives sunflower protein hydrolysate‐I (SFPH‐I). In a second step, SFPH‐I is treated with immobilized carboxypeptidase‐A at alkaline pH for quasi‐selective removal of aromatic amino acids (AAA). This sequential two‐step process, followed by size exclusion chromatography on a Sephadex G‐15 column, yields a product (SFPH‐II) with a BCAA concentration of 37.4±2.2% and an AAA concentration of 0.5±0.1%, which gives a very high Fischer ratio (≈75). The product, comprising mainly peptides with molecular weights in the range of 3500 to 750 Da and free amino acids, is hypoallergenic and shows no or only a trace of bitterness. Any bitterness can be completely removed by treatment with Flavozyme®, giving a hydrolysate that is composed mainly by tri‐ and dipeptides and free amino acids, and is termed highly hydrolyzed protein hydrolysate (HHPH). Both SFPH‐II and HHPH can be used in enteral, parenteral, and oral nutrition for the treatment of patients with liver failure. This product presents all the conditions required for use in the treatment of patients with liver failure: high content in BCAA and low content in AAA, below 2%, and consequently, a very high Fischer ratio, ≈75.

Enzymatic Modification of a Whey Protein Isolate to a Peptide Mixture with a High Fischer Ratio.

Enzymatic Modification of a Whey Protein Isolate to a Peptide Mixture with a High Fischer Ratio.

Low Molecular Weight Sunflower Protein Hydrolysate with Low Concentration in Aromatic Amino Acids

A method to obtain low molecular weight hydrolysates with a high Fischer ratio (molar ratio of Val + Leu + Ile to Tyr + Phe) is described. Sunflower protein concentrate, with a low concentration in...

Nutritional Effects of an Oligopeptide Mixture with a Very High Fischer Ratio on the Amino Acid Absorption and Cerebral Amine Metabolism in Rats Suffering from Galactosamine-induced Liver Injurry.

We have proposed a method to produce an oligopeptide mixture from zein by enzymatic modification to improve the Fischer ratio. In this study we produced the oligopeptide mixture on an enlarged scale and evaluated it in comparison with a corresponding amino acid mixture by feeding tests with normal and liver-injured rats. Both of the oligopeptide mixture and the amino acid mixture enhanced the Fischer ratio in plasma and brain at a similar degree. In rats suffering from severe hepatic injury, undesirable aromatic amino acids were absorbed from the oligopeptide mixture to a less extent than from the amino acid mixture. Peptide feeding, as well as amino acid feeding, resulted in decreasing concentrations of tryptophan and serotonin and in keeping the concentrations of dopamine and norepinephrine in cerebrum. These results suggest that the oligopeptide mixture is useful for patients with severe heptic disease.

Enzymatic modification of zein to produce a non-bitter peptide fraction with a very high Fischer ratio for patients with hepatic encephalopathy.

A method was proposed to produce a peptide fraction from zein by enzymatic hydrolysis to improve the Fischer ratio, i.e., the molar ratio of the branched chain amino acids, leucine, isoleucine and valine, vs. the aromatic amino acids, phenylalanine and tyrosine. Zein was hydrolyzed first with alkalophilic proteinase and then with actinase to liberate aromatic amino acids. The hydrolysate, however, tasted bitter and it was modified with transglutaminase to decrease the bitterness. Sephadex G-15 adsorption chromatography was used on the debittered product to remove the aromatic amino acids liberated. A series of these enzymatic modifications and the chromatography afforded a final product with a Fischer ratio of 20.0 at a yield of 56% on a nitrogen basis. Such a very high Fischer ratio and a reasonable yield would warrant economic feasibility for producing this formula on an industrial scale.