• Microbiology and Biotechnology Letters
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• v.35 no.4
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• pp.278-284
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• 2007

A novel screening strategy for salt-resistant antimicrobial peptides from a M13 peptide library was developed. Fusion of MSI-344, a magainin derivative and indolicidin to pIII coat proteins did not significantly affect viability of the recombinant phages, which indicated that the pIII could neutralize toxicity of the antimicrobial peptides and therefore it is possible to construct antimicrobial peptide library in Escherichia coli. On the basis of the conserved sequence of ${\alpha}$-helical antimicrobial peptides, a semi-combinatorial peptide library was constructed in which the peptides were displayed by pIII. To remove hemolytic activity from the library, the phages bound to red blood cells were removed, and the subtracted phage library was screened for binding to target bacteria Pseudomonas aeruginosa and Staphylococcus aureus under high salt concentrations. The screened peptides showed relatively low antimicrobial activity against the target bacteria. However, antimicrobial activities of the screened peptides P06 and S18 were not affected by the cation concentrations of 150 mM $Na^+$, 2 mM $Mg^{2+}$ and 2 mM $Ca^{2+}$ without significant hemolytic activity. This screening strategy that is based on binding capacity to target cells provides new potential to develop salt-tolerant antimicrobial peptides.

• Bulletin of the Korean Chemical Society
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• v.32 no.9
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• pp.3327-3332
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• 2011

Antimicrobial peptides have recently gained the much attention because of their ability to make defense system from attacking bacterial infections. Drosocin has been considered as very attractive antibiotic agents because of low toxicity against human erythrocytes and active at the low concentration. We have studied the structureactivity relationship of a glycopeptide drosocin focused on the N-acetyl-D-galactoside at $Thr^{11}$ residue. Based on the radial diffusion assay, we found that the acetylation of carbohydrate moiety increased the antimicrobial activity and the $Pro^{10}$, present in the middle of drosocin plays an important role in the antimicrobial activity. Our results provide a good lead compound for further studies on the design of drosocin-based analogues targeting glyco linked Thr site.

• Journal of the Korean Applied Science and Technology
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• v.36 no.3
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• pp.1018-1027
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• 2019

Natural-derived protein-derived low molecular weight peptides have been known to have physiological activities such as antioxidant, hypertension relief, immunomodulation, pain relief and antimicrobial activity. In this study, the low-molecular peptides were produced using commercial proteases (alcalase, bromelain, flavourzyme, neutrase, papain, protamex), and the antioxidant activity (DPPH scavenging activity, superoxide radical scavenging activity, hydroxy radical scavenging activity, and metals chelation capacity), constituent amino acid and molecular weight of the peptide were analyzed. Enzyme reaction was performed by adding 50 g of chopped Ogae meat slurry and 2%(w/v) protein enzyme into the enzyme reactor for 2 h at a pH of 6 and a temperature of $60^{\circ}C$. The degree of hydrolysis(%) after the reaction ranged from $36.65{\pm}4.10%$ to $70.75{\pm}5.29%$. The highest degree of hydrolysis of protamex was 46.3%, and the highest value of papain hydrolysate was $70.75{\pm}5.29%$. On the other hand, alcalase hydrolysate showed the lowest value of $36.65{\pm}4.10%$. Bromelain-treated low molecular weight peptides showed the highest DPPH radical scavenging activity and the lowest scavenging activity of alcalase-treated peptides. Superoxide radical scavenging activity showed that bromelain treated low molecular peptide showed the highest radical scavenging activity of 50% or more. Hydroxyl radical scavenging activity ranged from about 16.73 to 69.16%, the highest among bromelain-treated low molecular peptides. $Fe^{2+}$ chelation abilities showed a distribution between about 17.85 to 47.84%. The chelation capacity of the hydrolysates was not significantly different without any difference to the enzymes used. The results of amino acid analysis showed differences between hydrolysates of alcalase, bromelain, flavourzyme, neutrase, papain, and protamex enzymes. The most amino acid was glutamic acid. The molecular weight distribution of the enzyme hydrolyzates was in the range of 300-2,000 Da, although the molecular weight distribution differed according to the treated enzymes.

• Molecules and Cells
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• v.44 no.5
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• pp.328-334
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• 2021

The advent of the major histocompatibility complex (MHC) multimer technology has led to a breakthrough in the quantification and analysis of antigen-specific T cells. In particular, this technology has dramatically advanced the measurement and analysis of CD8 T cells and is being applied more widely. In addition, the scope of application of MHC multimer technology is gradually expanding to other T cells such as CD4 T cells, natural killer T cells, and mucosal-associated invariant T cells. MHC multimer technology acts by complementing the T-cell receptor-MHC/peptide complex affinity, which is relatively low compared to antigen-antibody affinity, through a multivalent interaction. The application of MHC multimer technology has expanded to include various functions such as quantification and analysis of antigen-specific T cells, cell sorting, depletion, stimulation to replace antigen-presenting cells, and single-cell classification through DNA barcodes. This review aims to provide the latest knowledge of MHC multimer technology, which is constantly evolving, broaden understanding of this technology, and promote its widespread use.

• Applied Chemistry for Engineering
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• v.24 no.1
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• pp.18-23
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• 2013

In this research, the collagen peptide powder from flatfish skin (FSCP) was prepared and compared with commercial collagen peptide powder from tilapia scale (TSCP) in the aspect of physiochemical property. The physical property and nutritional components of FSCP appeared almost similarly to those of TSCP, and also in calorie. No differences in calorie between FSCP and TSCP. Amino acid contents of FSCP for example, aspartic acid, serine, histidine, tyrosine and methionine were higher than those of TSCP. In contrast, the hydroxyproline, proline, alanine contents in FSCP were lower than those in TSCP. Especially, the content of essential amino acid of FSCP, which was 22.74%, was higher than that of TSCP evaluated as 13.64%. In the distribution of molecular weight, FSCP was 1000 Da, which showed a comparatively low distribution compared with TSCP, and in emulsion property and stability both FSCP and TSCP showed an excellent trend.

• Food Science and Preservation
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• v.16 no.6
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• pp.938-945
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• 2009

The objective of this study was to investigate the effects of ingestion of low-molecular-weight collagen peptides on lipid composition, blood glucose level, and enzyme activities in the serum of hyperlipidemic rats fed experimental diets for 5 weeks. Concentrations of total cholesterol, low-density lipoprotein (LDL)-cholesterol, free cholesterol, triglyceride (TG), phospholipid (PL), and blood glucose, the atherosclerotic index, and the cholesteryl ester ratio were higher in serum of the hyperlipidemic group (CW group), and the cholesterol-plus-collagen peptides extract group (CCP group) than in the control group (BG group basal diet plus water). However, the concentrations of total cholesterol, LDL-cholesterol, free cholesterol, TG, PL, and blood glucose, the atherosclerotic index, and the cholesteryl ester ratio in serum were lower in the CCP group than in the CW group. By contrast, the ratio of HDL-cholesterol to total cholesterol and the absolute HDL-cholesterol level in the CCP group were higher than in the CW group. The activities of alkaline phosphatase (ALP) and aminotransferases (AST, ALT) in serum were lower in the CCP group than in the hyperlipidemic CW group. The results indicate that an extract of low-molecular-weight collagen peptides effectively inhibited increases in lipid elevation, blood glucose level, and enzyme activities, in the serum of hyperlipidemic rats.

• BMB Reports
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• v.35 no.2
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• pp.172-177
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• 2002

We previously reported that cholesteryl ester transfer protein (CETP) inhibitory peptides (designated $P_{28}$ and $P_{10})$ have anti-atherogenic effects in hypercholesterolemic rabbits (Biochim. Biophys. Acta (1998) 1391, 133-144). To further investigate those effects, we studied rabbit plasma that was collected after 30 h of a $P_{28}$ or $P_{10}$ injection. We found that there is a strong correlation between the in vivo CETP inhibition effects and alterations of lipoprotein particle size distribution in rabbit plasma, as determined on an agarose gel electrophoresis and gel filtration column chromatography. In vivo effects of the peptide were observed again in C57BL/6 mice that expressed simian CETP. The $P_{28}$ or $P_{10}$ peptide ($7\;{\mu}g/g$ of body weight) that was dissolved in saline was injected subcutaneously into the mice. The $P_{28}$ injection caused the partial inhibition of plasma CETP activity up to 50%, decreasing the total plasma cholesterol concentration by 30%, and increasing the ratio of HD/total-cholesterol concentration by 150% in the CETP-transgenic (tg) mice. The CETP inhibition by the $P_{28}$ or $P_{10}$ made alterations that modulated the size re-distribution of the lipoproteins in the blood stream. Particle size of the very low (VLDL) and low density lipoproteins (LDL) from the peptide-injected group was highly decreased compared to the saline-injected group (determined on the gel filtration column chromatography). In contrast, The HDL particle size of the $P_{28}$-injected group increased compared to the control group (saline-injected). The expression level of the CETP mRNA of the $P_{28}$-injected CETP-tg mouse appeared lower than the saline-injected CETP-tg mouse. These results suggest that the injection of the CETP inhibitory peptide could affect the CETP expression level in the liver by influencing lipoprotein metabolism.

• Food Science and Biotechnology
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• v.15 no.5
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• pp.698-703
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• 2006

We investigated how the addition of polypeptides to instant fried noodle dough affects the dough properties, starch gelatinization, and textural properties of cup-type instant fried noodles. After comparing farinograph results of 100% wheat flour with 1% wheat flour substituted with gluten, there was a small difference in the mechanical dough properties. However, in the case of 1% wheat flour substituted with gluten peptides, the dough development time increased, dough stability decreased, and weakness increased. On the other hand, when gluten or gluten peptides were added, starch gelatinization did not change significantly. At the steaming stage, substitution with gluten peptides or soybean peptides markedly changed the molecular weight distributions of extractable polypeptides. Especially in the case of wheat flour substituted with 1% gluten peptides, the relative portion of low Mw extractable polypeptides (2.5-50 kDa) decreased more compared to a control. Also, the hardness and chewiness decreased in cooked cup-type instant fried noodles containing gluten peptides. This suggests that the addition of gluten peptides can reduce the rehydration time of cup-type instant fried noodles.

• Journal of Food Hygiene and Safety
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• v.35 no.5
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• pp.513-520
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• 2020

Here, we evaluated the functional properties of histidine-containing low-molecular-weight (LMW) peptides obtained from tuna waste meats. As with histidine-related components composed of histidine, 1-methyl histidine and anserine, histidine-containing LMW peptides exhibited high α,α-diphenyl-β-picrylhydrazyl (DPPH) radical scavenging effect in a dose-dependent manner. Among the histidine-related dipeptides, anserine exhibited the highest reducing power followed by carnosine. By comparison with dipeptides, tuna extracts also showed similar reducing power and the activity was in a dose-dependent manner. In addition, the antioxidant activities of tuna extracts such as DPPH radical scavenging effect, reducing power, superoxide dismutase activities, and peroxide value of linoleic acid were affected by the various extraction methods.

• Preventive Nutrition and Food Science
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• v.10 no.3
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• pp.239-243
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• 2005

Angiotensin I-converting enzyme (ACE) inhibitory activities of elk antler hydrolysates prepared with three kinds of proteases, pepsin, trypsin and $\alpha-chymotrypsin$, were investigated. The ACE inhibitory activity of the pepsinolytic hydrolysate was the highest with an $IC_{50}$ value of $9.3\mu g/mL.$ In addition, three kinds of pepsinolytic hydrolysates with relatively high molecular weights (over 10,000 Da), medium molecular weights (5,000 to 10,000 Da), and low molecular weights (below 5,000 Da) were fractionated using an ultrafiltration membrane system. The below 5,000 Da hydrolysate exhibited the highest ACE inhibitory activity. These results indicate that the pepsinolytic hydrolysates of elk velvet antler could be a good source of peptides with ACE inhibitory activity.