• Journal of the Korean Chemical Society
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• 제14권2호
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• pp.155-160
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• 1970

The kinetics of the pepsin-catalyzed hydrolysis of N-carbobenzoxy-L-glutamyl-L-tyrosine at pH 3.5 and $37^{\circ}C$ were determined by a spectrophotometric technique. The pepsin used was further purified on a Sephadex G-75 column. The kinetics data were Km = l.7 ${\times}10^{-3}M,\;-{\Delta}F^{\circ}$ = 3.99Kcal/mole, and $k^3=\;2.1{\times}10^{-2}\;sec^{-1}$. An analysis of the above data and other investigators' data obtained from some dipeptides led to the following conclusions. (1) Phenylalanyl residues in a synthetic peptide are bound to pepsin more strongly than glutamyl or tyrosyl residues, supporting the theory that a part of the binding region of the active center is hydrophobic. (2) Dipeptides are bound to pepsin principally through their side chains and the binding involves both side-chain residues. (3) The nature of amino acids in dipeptides $R_2-R_1,\;affect\;the\;k_3$ values.

• Journal of the Korean Applied Science and Technology
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• 제3권1호
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• pp.43-47
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• 1986

1.2-bis(aminoacyl)hydrazine derivatives and dipeptides were synthesized by conventional peptide synthesis procedures. Their antioxidant activity were inverstigated by over-storage test using corn oil as substrte. 1.2-bis (aminoacyl) hydrazine derivatives and dipetides containing hydrophobic side chain amino acid showed higher antioxidant activity. A free N-terminal amino group was also found to be important for the appearance of antioxidant activity. 1.2-bis (aminoacyl) hydrazine derivatives showed higher antioxidant activity than dipeptides. Antimicrobial activites of dipeptides and 1.2-bis (aminoacyl) hydrazine derivatives were also examined by the paper disc method. All of these compounds had shown no antimicrobial activity.

• Bulletin of the Korean Chemical Society
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• 제29권9호
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• pp.1732-1736
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• 2008

The endogenous dipeptides, carnosine and related compounds, are the naturally occurring dipeptides with multiple neuroprotective properties. We have examined the protective effects of carnosine, homocarnosine and anserine on the aggregation of neurofilament-L (NF-L) induced by neurotoxin, acrolein. When NF-L was incubated with acrolein in the presence of carnosine, homocarnosine or anserine, protein aggregation was inhibited in a concentration-dependent manner. These compounds inhibited the formation of protein carbonyl compounds and dityrosine in acrolein-mediated NF-L aggregates. The aggregates of NF-L displayed thioflavin T reactivity, reminiscent of amyloid. This thioflavin T reactivity was inhibited by carnosine and related compounds. This effect was associated with decreased formation of oxidatively modified proteins. Our results suggested that carnosine and related compounds might have protective effects to brain proteins under pathophysiological conditions leading to degenerative damage such as neurodegenerative disorders.

• Journal of Nutrition and Health
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• 제53권4호
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• pp.356-368
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• 2020

Purpose: Histidine-containing dipeptides, which are rich in chicken, have been reported to reduce the risk of metabolic abnormalities via anticarbonylation mechanism in animal models. To determine the effect of dietary histidine-containing dipeptides on metabolic risk factors in humans, the relation between chicken consumption and insulin resistance were determined in a population consuming high carbohydrate and low protein. Methods: A total of 7,183 subjects (2,929 men and 4,254 women) aged ≥ 50 years from the Korea National Health and Nutrition Examination Survey (KNHANES) were divided into three groups according to chicken consumption (rarely, monthly, and weekly), and evaluated for the metabolic risk factors using homeostasis model assessment for insulin resistance (HOMA-IR) and quantitative insulin sensitivity check index (QUICKI) in this cross-sectional study. The fourth and fifth (IV-1-3 & V-1) KNHANES, which had blood insulin data, were chosen for the current study. Results: The chicken consumption was significantly associated with insulin (p for trend = 0.018) and HOMA-IR (p for trend = 0.023) in men. In particular, the 'weekly' chicken consuming men in the lowest tertile (< 65.0%) of carbohydrate intake group had significantly lower HOMA-IR (p for trend = 0.033) and higher QUICKI (p for trend = 0.043) than the 'rarely' intake group. In addition, the odds ratio for abnormal HOMA-IR was 0.55 (95% confidence interval [CI], 0.31-0.99) and QUICKI was 0.47 (95% CI, 0.26-0.86) for the 'weekly' chicken consuming group. Conclusion: The 'weekly' chicken consumption had a beneficial effect on insulin resistance and it may partially be due to the major bioactive components in chicken, histidine-containing dipeptides.

• Asian-Australasian Journal of Animal Sciences
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• 제26권4호
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• pp.501-508
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• 2013

The effects of amino acids and dipeptides on in vitro production of porcine embryos and accumulation of ammonia in culture medium during developmental stages were examined in this study. The maturation, fertilization and development of embryonic cultures were performed in modified Tissue culture medium (mTCM)-199 supplemented with 10% (v/v) porcine follicular fluid, modified Tyrode's albumin lactate pyruvate (mTALP) medium, and modified North Carolina State University (mNCSU)-23 medium, respectively. In addition, amino acids and dipeptides of different concentrations and combinations were used to treat the embryos. The addition of L-alanyl-L-glutamine (AlnGln)+L-glycyl-L-glutamine (GlyGln) significantly (p<0.05) improved oocyte maturation, fertilization and the incorporation and oxidation of 14C(U)-glucose when compared to the control group and other treatment groups. Additionally, 2-4 cell, 8-16 cell, morula and blastocyst development increased significantly (p<0.05) following treatment with AlnGln+GlyGln when compared to the control group and other treatment groups, while this treatment reduced the accumulation of ammonia. Taken together, these findings suggest that treatment with AlnGln+GlyGln may play an important role in increasing the rate of porcine oocyte maturation, fertilization and embryonic development by reducing the level of accumulated ammonia measured in the culture media.

• Bulletin of the Korean Chemical Society
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• 제18권8호
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• pp.899-902
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• 1997

• Journal of the Korean Chemical Society
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• 제21권3호
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• pp.171-179
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• 1977

Proton magnetic resonance spectra of five glycine-containing dipeptides glycyl-L-valine, L-valyl-glycine, glycyl-DL-alanine, glycyl-DL-serine and glycyl-L-aspartic acid in $D_2O$ were investigated as a function of pH at room temperature. From the analysis of the spectra, it was found that the chemical shift of the $C_{\alpha}H,\;C_{\beta}H\;and\;C_rH$protons varies with pH as a one-step titration curve, and that the spin-spin coupling constant remains almost unchanged. Two distinct values of the chemical shift for $C_{\alpha}H,\;C_{\beta}H\;or\;C_rH$protons of constituent amino acids in dipeptide solutions indicate the existence of two magnetically non-equivalent sites in solution. From this study, the structures of the five dipeptides have been confirmed by proton magnetic resonance spectra and it has been suggested that the structural change, conformation and sequence determination can be explored for oligopeptides by an analysis of proton magnetic resonance spectra.

• Food Science of Animal Resources
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• 제41권5호
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• pp.788-801
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• 2021

This study examined biochemical components, fatty acids, antioxidant dipeptides, and muscle fiber density of breast and thigh muscles from Korean new native chicken strains (A and B) at two slaughter ages, compared with white semi-broiler (W) or broilers. The pH values were different by chicken breed. The new native strains had the lowest fat content in the breast at 12 wk (p<0.05). Regardless of the muscles, A and B at 12 wk had higher levels of arachidonic acid (ARA; C20:4), docosahexaenoic acid (DHA; C22:6), and nervonic acid (C24:1) than broilers (p<0.05). A similar result was observed for the polyunsaturated fatty acids (PUFAs) and polyunsaturated and saturated fatty acids ratio (P/S) content in the breast. Irrespective of the muscles, A and B enriched with omega-3 fatty acids had a lower ω-6/ω-3 PUFA ratio than broilers (p<0.05) at 12 wk. Of the antioxidant di-peptides, the anserine contents were highest in A and B than in the W or broilers (p<0.05), regardless of the muscles and slaughter ages. Furthermore, the breast meat from A and B contained a higher muscle fiber density for both slaughter ages than the W and broilers (p<0.05). Based on these findings, even if the commercial birds (broilers or W) are raised under the similar environmental conditions as A and B, the new native chicken strains have distinct meat quality attributes, particularly higher ARA and DHA levels, lower ω-6/ω-3 PUFA ratio, and higher anserine contents.

• Journal of Microbiology and Biotechnology
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• 제34권2호
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• pp.314-329
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• 2024

Fifteen cyclic dipeptides (CDPs) containing proline, one cyclo(Phe-Ala) without proline, and a non-peptidyl ᴅⳑ-3-phenyllactic acid were previously identified in the culture filtrates of Lactobacillus plantarum LBP-K10, an isolate from kimchi. In this study, we used Japanese quail (Coturnix japonica) eggs to examine the effects of probiotic supplementation on the antimicrobial CDPs extracted from quail eggs (QE). Eggshell-free QE were obtained from two distinct groups of quails. The first group (K10N) comprised eggs from unsupplemented quails. The second group (K10S) comprised eggs from quails supplemented with Lb. plantarum LBP-K10. The QE samples were extracted using methylene chloride through a liquid-liquid extraction process. The resulting extract was fractionated into 16 parts using semi-preparative high-performance liquid chromatography. Two fractions, Q6 and Q9, were isolated from K10S and identified as cis-cyclo(ⳑ-Ser-ⳑ-Pro) and cis-cyclo(ⳑ-Leu-ⳑ-Pro). The Q9 fraction, containing cis-cyclo(ⳑ-Leu-ⳑ-Pro), has shown significant inhibitory properties against the proliferation of highly pathogenic multidrug-resistant bacteria, as well as human-specific and phytopathogenic fungi. Some of the ten combinations between the remaining fourteen unidentified fractions and two fractions, Q6 and Q9, containing cis-cyclo(ⳑ-Ser-ⳑ-Pro) and cis-cyclo(ⳑ-Leu-ⳑ-Pro) respectively, demonstrated a significant increase in activity against multidrug-resistant bacteria only when combined with Q9. The activity was 7.17 times higher compared to a single cis-cyclo(ⳑ-Leu-ⳑ-Pro). This study presents new findings on the efficacy of proline-containing CDPs in avian eggs. These CDPs provide antimicrobial properties when specific probiotics are supplemented.

• Journal of the Society of Cosmetic Scientists of Korea
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• 제38권1호
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• pp.67-73
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• 2012

In the present study, we investigated the effects of dipeptides on melanogenesis in B16 melanoma cells. It was found that WV (Trp+Val), WM (Trp+Met), and CQ (Cys+Gln) decreased melanin production dosedependently. However, dipeptides did not directly inhibit tyrosinase activity, the rate-limiting melanogenic enzyme. Therefore, we further investigated the expression of tyrosinase. Our results showed that ${\alpha}$-MSH-induced tyrosinase expression was down-regulated by WV, WM, and CQ. Thus, we propose that WV, WM, and CQ show hypopigmentary activity through tyrosinase down-regulation.