• BMB Reports
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• v.35 no.2
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• pp.239-243
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• 2002

Angiotensin I that converts the enzyme (ACE) inhibitory peptide, Gly-Pro-Leu, previously purified and identified from the Alaskan pollack skin gelatin hydrolysate, were synthesized. In addition, the peptides Gly-Leu-Pro, Leu-Gly-Pro, Leu-Pro-Gly, Pro-Gly-Leu, Pro-Leu-Gly, Gly-Pro, and Pro-Leu, which consisted of glycine, proline, and leucine, were synthesized by the solid-phase method. The $IC_{50}$ values of each tripeptide - namely Leu-Gly-Pro, Gly-Leu-Pro, Gly-Pro-Leu, Pro-Leu-Gly, Leu-Pro-Gly, and Pro-Gly-Leu - were 0.72, 1.62, 2.65, 4.74, 5.73, and $13.93{\mu}M$, respectively. The ACE inhibitory activity of these tripeptides was higher than that of dipeptides, such as Gly-Pro and Pro-Leu with $IC_{50}$ values of 252.6 and $337.3\;{\mu}M$, respectively. Among the tripeptides, Leu-Gly-Pro and Gly-Leu-Pro had higher inhibitory activity than Gly-Pro-Leu that was isolated from the Alaskan pollack skin gelatin hydrolysate. Among the different types of tripeptides that were examined, the highest ACE inhibitory activity was observed for Leu-Gly-Pro. It had the leucine residue at the N-terminal and proline residue at the C-terminal.

• Journal of the Korean Chemical Society
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• v.19 no.2
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• pp.134-141
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• 1975

DL-1-aminoethylphosphonic acid(1-AEP) and DL-1-aminopropylphosphonic acid(1-APP) were synthesized from the propionic acid and butyric acid respectively using the modified cutius degradation. The following unreported derivatives containing peptide linkage were synthesized: N-phthalylglycyl-1-AEP, N-phthalyl-dl-alanyl-1-AEP, N-phthalyl-dl-phenylalanyl-1-AEP, N-phthalylglycyl-1-APP, N-tosylglycyl-1-AEP and N-tosyl-dl-alanyl-1-AEP These compounds were characterized and identified by means of elemental analysis, potentiometric titration, infrared spectroscopy and ninhydrin test.

• Food Science and Industry
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• v.51 no.4
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• pp.313-324
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• 2018

As excessive intake of salt is regarded as a reason for health problems, the tendency of people to attempt to reduce intake of salt in their everyday lives is on the rise. In Korea, where many people have a higher intake of salt compared to those in other countries, there have been diverse efforts to improve on this eating habit. Protein hydrolysates are chemically, physically hydrolyzed protein that have been widely utilized as a material for not only regular food but health functional food due to have diverse biological effects such as anti-oxidation, anti-inflammation, prevention of diabetes, and regulation of blood pressure. Various amino acids such as glutamic acid, arginine and arginine dipeptides, which exist in the components of protein hydrolysates, have also been recently recognized as being helpful in decreasing the use of salt in foods as they can greatly enhance salty taste when used concurrently with salt due to having both salty and palatable flavors. In the case of protein hydrolysates that decompose soy protein or fish protein such as anchovy, they could reduce consumption of salt by as much as 50% without affecting people's food preferences when applied to food as they boost salty taste by approximately 10% to 70%. Although there are only a few studies on protein hydrolysates as a salty taste enhancer or salt substitute, the results of several studies are indicative of the potential of protein hydrolysates as a salty taste enhancing ingredient.

• Bulletin of the Korean Chemical Society
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• v.31 no.3
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• pp.611-614
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• 2010

Substituted imidazolidin-2-ones deduced as potential inhibitors of IleRS by docking simulations were synthesized from an aziridine-2-carboxaldehyde. Reductive amination of an aziridine-2-carboxaldehyde with dipeptides for the substituents at N1 and followed by aziridine-ring expansion with triphosgene afforded 4-chloromethylimidazolidin-2-ones whose chloride were further manipulated towards phenylurea, pyrimidin-2-yl-urea or benzenesulfonamide at C4.

• Asian-Australasian Journal of Animal Sciences
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• v.12 no.1
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• pp.139-147
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• 1999

Peptides are formed in the rumen as the result of microbial proteinase activity. The predominant type of activity is cysteine ptoteinase, but others, such as serine proteinases, are also present. Many species of protozoa, bacteria and fungi are involved in ptoteolysis; large animal-to-animal variability is found when proteinase activities in different animals are compared. The peptides formed from proteolysis are broken down to amino acids by peptidases. Different peptides are broken down at different rates, depending on their chemical composition and particularly their N-terminal structure. Indeed, chemical addition to the N-terminus of small peptides, such as by acetylation, causes the peptides to become stable to breakdown by the rumen microbial population; the microorganisms do not appear to adapt to hydrolyse acetylated peptides even after several weeks exposure to dietary acetylated peptides, and the amino acids present in acetylated peptides are absorbed from the small intestine. The amino acids present in some acetylated peptides remain available in nutritional trials with rats, but the nutritive value of the whole amino acid mixture is decreased by acetylation. The genus Prevotella is responsible for most of the catabolic peptidase activity in the rumen, via its dipeptidyl peptidase activities, which release dipeptides rather than free amino acids from the N-terminus of oligopeptides. Studies with dipeptidyl peptidase mutants of Prevotella suggest that it may be possible to slow the rate of peptide hydrolysis by the mixed rumen microbial population by inhibiting dipeptidyl peptidase activity of Prevotella or the rate of peptide uptake by this genus. Peptides and amino acids also stimulate the growth of rumen microorganisms, and are necessary for optimal growth rates of many species growing on tapidly fermented substrates; in rich medium, most bacteria use pre-formed amino acids for more than 90% of their amino acid requirements. Cellulolytic species are exceptional in this respect, but they still incorporate about half of their cell N from pre-formed amino acids in rich medium. However, the extent to which bacteria use ammonia vs. peptides and amino acids for protein synthesis also depends on the concentrations of each, such that preformed amino acids and peptides are probably used to a much lesser extent in vivo than many in vitro experiments might suggest.

• BMB Reports
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• v.32 no.4
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• pp.350-357
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• 1999

At concentrations of 1 mM, the protective effects of carnosine and related compounds including anserine, homocarnosine, histidine, ${\beta}$-alanine were investigated against copper-catalyzed oxidative damage to deoxyribose, ascorbic acid, human serum albumin, liposome, and erythrocytes. Carnosine and anserine reduced Cu (II) to bathocuproine-reactive Cu (I) in a time- a and a dose-dependent manner while the others did not. Carnosine reduced 86% of $100\;{\mu}M$ Cu (II) in 60 min. Carnosine, homocarnosine, anserine, and histidine inhibited copper-catalyzed deoxyribose degradation by 75, 66, 65, and 45%, respectively. In the presence of $1\;{\mu}M$ Cu (II), carnosine and related compounds inhibited ascorbic acid oxidation by 55-85% after incubation for 20 min. In the presence of 0.15 mM ascorbic acid and 0.8 mM $H_2O_2$, carnosine, anserine, homocarnosine, and histidine inhibited copper-catalyzed oxidation of human serum albumin by 41, 21, 29, and 24%, respectively, as determined by carbonyl formation. These compounds also significantly inhibited copper-catalyzed liposomal lipid peroxidation as measured by malondialehyde and lipid hydroperoxides. Carnosine, anserine, homocarnosine, and histidine inhibited hemolysis of bovine erythrocytes induced by 0.1 mM Cu (II). These results suggest that histidine-containing dipeptides may play an important role in protecting against free radical-mediated tissue damage.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.22 no.5
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• pp.228-232
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• 1989

Katsuobushi has widely been used from olden times to prepare soup stock. This study was carried out to prepare stock of powdered Katsuobushi, and to examine the extractive conditions and the contribution of principal taste compounds to its characteristic taste. The extractive condition of powdered Katsuobushi in preparing stock was the most appropriate at $100^{\circ}C$ for 1 minute boiling water-steeping method in flavor, clearance of stock. From the chemical analysis and omission test, the principal taste-active components in $4\%$ solution powdered Katsuobushi under this extractive condition were nucleotides 93.6mg/100ml, free amino acids and imidazole dipeptides 41.3mg/100ml, and non-volatile organic acids 39.3mg/100l1 in order. IMP, inosine, AMP, histidine, anserine, taurine, carnosine and lactic acid were predominant among the detected compounds.

• The Korean Journal of Food And Nutrition
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• v.28 no.6
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• pp.1019-1025
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• 2015

The influence of aging on the flavor precursors and volatile compounds of top round beef was studied. The concentrations of free amino acids, nucleotides, creatine, dipeptides, and volatile compounds were measured after top round from Hanwoo was aged at $4^{\circ}C$ for 21 days. The amount of free amino acids in top round significantly increased with the increase of aging period. There was no effect of aging on the concentrations of adenosine monophosphate or inosine in top round. The inosine monophosphate content of top round significantly decreased with age, while the hypoxanthine content increased. The concentrations of creatine, carnosine, and anserine in top round were not influenced by aging. In total, 24 volatile compound were identified in aged, cooked top round. Of these, the quantities of aldehydes (propanal, pentanal, hexanal, heptanal, octanal, and nonanal), hydrocarbons (pentane and octane), 2-butanone, ethyl acetate, and pyridines (4-ethynyl-pyridine and 4-acetyl-pyridine) significantly increased after aging. We conclude that the flavor of top round can be improved by aging.

• KSBB Journal
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• v.32 no.1
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• pp.71-82
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• 2017

To verify anti-diabetic effect of oligopeptide with His-Pro repeats (mHP peptide), the oligopeptide was first secreted and optimized using the secretion vector, pRBAS with alkaline protease gene promoter and the signal sequence in Bacillus subtilis and directly the anti-diabetic effect of the mHP peptide was investigated in insulinoma cell, RINm5F cell line. The oligopeptide gene was obtained by annealing oligonucleotides with repeated His-Pro sequence and finally was constructed as 18 dipeptides (108 bp and 4.0 kDa) coding gene, named oligopeptide with His-Pro repeats (mHP peptide) to make cyclo(His-Pro) known to be anti-diabetic effects. The region encoding the oligopeptide gene was subcloned into the pRBAS secretion vector (E.coli-Bacillus shuttle vector) after PCR amplification using the designed primers including initiation and termination codons and His tag, named pRBAS-mHP (6.56 kb). To optimize secretion of the oligopeptide, various culture conditions were investigated in Bacillus subtilis LKS. As a result, the secreted oligopeptide was maximally measured (approximately $59.6{\mu}g/mL$) in 3 L batch culture and the highest secretion was achieved at $30^{\circ}C$, PY medium, and carbon sources (particularly barley and glycerol). In the RINm5F cells treated with 2 mM STZ, the oligopeptide treatment (0.1 mg/mL) restored the cell viability (10%) and reduced the nitric oxide (NO) generation (35%) and DNA fragmentation (90%). And also, insulin secretion level was increased to 17% higher than in STZ-treated RINm5F cells. These results suggest that the oligopeptide with His-Pro repeats could be a candidate material for anti-diabetic agent against STZ-induced diabetes.

• Bulletin of the Korean Chemical Society
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• v.29 no.5
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• pp.1025-1032
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• 2008

(4,5-Dichloro-6-oxo-6H-pyridazin-1-yl)phosphoric acid diethyl ester (3a) are efficient and selective coupling agents for the amidation of carboxylic acids. Amidation of aliphatic and aromatic carboxylic acids with aliphatic and aromatic amines using 3a under mild condition gave chemoselectively the corresponding amides in good to excellent yield. Three protected-dipeptides were also synthesized from N-BOC-Phe and O-Me-amino acid hydrochlorides using 3a under mild condition.