• Microbiology and Biotechnology Letters
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• v.30 no.1
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• pp.39-45
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• 2002

It was found that the peptides originated from the hydrolysates of silk fibroin have in vitro immunostimulating effects in murine macrophage RAW264.7 cells. The stimulation effects on nitric oxide (NO) production resulted from treatments of acid or enzymatic hydrolysates were measured. The silk fibroin preparation isolated from cocoon was most efficiently digested by acid hydrolysis. Even though the sole treatment of acid hydrolysate stimulated the NO production in dose-dependent pattern, a part of its activity was found to be caused by the contaminated endotoxin, LPS. When each endotoxin-free hydrolysates obtained by filtering it through an ultrafiltration membrane of molecular weight (MW) cut-off 10,000 to eliminate LPS was used, the peptic hydrolysate with lowest degree of hydrolysis showed the highest activity. The fractions of peptic hydrolysate with MW ranges of 1,000∼10,000, 500∼1,000 and below 500 also showed a higher MW-higher activity correlation. From the analyses of amino acid composition of each hydrolysate, it was found that the contents of arginine, lysine, alanine and glycine residues affected the activity level of hydrolysate. The results of this study showed a possibility of utilizing fibroin as a source for immunostimulating (chemopreventive) functional peptides.

• Journal of Life Science
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• v.22 no.2
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• pp.220-225
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• 2012

The peptides of enzymatic hydrolysates from oyster were determined by inhibitory activity against angiotensin-converting enzyme. The ACE inhibitory activity of enzymatic oyster hydrolysates increases with hydrolysis time. Among enzymatic oyster hydrolysates, oyster hydrolysates incubated with Protamex showed the best ACE inhibitory activity after 10 h. Hydrolysates were filtered through a HiSep ultrafiltration membrane (M.W. cut-off 30 kDa, 10 kDa) to obtain the peptide fractions with ACE inhibition activity. These fractions were applied to an HPLC column (watchers 120 ODS-AP $250{\times}4.6$ ($5{\mu}m$)). Six active fractions were collected and the range of ACE inhibition was from 29.56 to 85.85%. Peptide was purified from fraction B, showing the highest ACE inhibitory activity, and its sequence was Leu-Gln-Pro. These results suggest that PEH may be beneficial for developing antihypertensive food and drug.

• Microbiology and Biotechnology Letters
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• v.44 no.2
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• pp.124-129
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• 2016

The extraction and purification of the anti-hyperglycemic α-glucosidase inhibitor from an edible mushroom, Pleurotus cornucopiae, were investigated. The inhibitor was maximally extracted when the P. cornucopiae fruiting body was treated with distilled water at 30℃ for 12 h. Purification was achieved using Sephadex G-100 and G-50 filtration chromatography, pepsin hydrolysis, and reverse-phase HPLC. The compound’s solid yield and inhibitory activity were 12.2% and 9.10 mg/ml of IC₅₀, respectively. The purified inhibitor contained two hexapeptides with Thr-Ile-Ala-Phe-Ile-Asp (A) and Tyr-Tyr-Ala-Ile-Gly-Asp (B) sequences and molecular weights of 678.79 Da (A) and 643.7 Da (B). The purified inhibitor showed a mixed inhibition pattern to α-glucosidase and a dose-dependent anti-hyperglycemic effect in a streptozotocininduced diabetic Sprague-Dawley rat model, exhibited by decreased blood glucose levels at doses of 50 and 300 mg/kg.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.6
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• pp.875-881
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• 1998

To develop functional food material with angiotensin converting enzyme (ACE) inhibitory peptides, muscle protein of anchovy, Engraulis japonica was hydrolyzed during 48 hrs by digestive pretenses such as pepsin, trypsin, $\alpha$-chymotrypsin, and commercial proteases such as papain, bromelain, complex enzyme, Elavourzyme, Novozym, Neutrase, Protamex and Alcalase. The only $50\%$ ethanol soluble hydrolysates were tested for inhibitory activity against ACE and yield of $50\%$ ethanol soluble peptide-nitrogen ($ESPN_{50}$). ACE inhibition effects and yield of $ESPN_{50}$ occurred as hydrolysis time increased to 8 hrs, Among those pretenses tested, hydrolysates by Alcalase and $\alpha$-chymohypsin had greater ACE inhibitory activity (80 and $74\%$, reipectively) with eletated levels of $ESPN_{50}$ (48 and 58 mg/ml, respectively), while Protamex hydrolysates had greater ACE inhibitory activities ($73\%$) with reduced levels of $ESPN_{50}$ (7.2mg/ml) than others. Amino acid compositions of $50\%$ ethanol solubles obtained from those hydrolysates were rich in glutamic acid, aspartic acid, cysteine and leucine.

• Korean Journal of Food Science and Technology
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• v.27 no.2
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• pp.141-146
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• 1995

For the effective utilization of skipjack tuna viscera, a study was carried out to investigate the applicability of viscera protein hydrolysate (VPH) as a protein supplement in the processing of imitation sauce and bread. The optimum extraction and hydrolyzation conditions for the production of viscera protein concentrate (VPC) and viscera protein hydrolysate (VPH) were determined. Boiled viscera could be extracted by ethyl alcohol without significant deterioration as a raw material for the further processing. High quality of VPH could be obtained by hydrolysis with 1% pepsin under its optimum condition $(pH\;1.65,\;37^{\circ}C)$. The solubilities of VPC and VPH were 40% and 90%, respectively, and the essential amino acid contents in two products were 48.7% and 63.2%, respectively. Especially, the content of taurine, a physiologically important amino acid, was 9.4% in VPH. In experimental preparations of imitation sauce and bread, panel test showed that the supplementation of 10% of VPH in imitation sauce and $3{\sim}5%$ of VPH in bread was well accepted in sensory characteristics such as color, flavor, taste and texture.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.25 no.3
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• pp.229-235
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• 1992

Fish protein hydrolysates(FPH) prepared from defatted mackerel meal by proteases such as complex enzymes, bromelain, alcalase, $\alpha-chymotrypsin,$ trypsin, papain and pepsin were tested for inhibitory activity against angiotensin-I converting enzyme(ACE). Among proteases tested, the hydrolysates obtained from the treatment of complex enzymes or bromelain showed relatively higher activity. ACE inhibitory activity of the hydrolysates increased until hydrolysis of 8 hrs, and was stable by heat treatment for 20min at $100^{\circ}C.$ From the profiles of fractionation of the hydrolysates with Bio-gel P-2, the most active fraction had about MW 1,450 and it's amino acid was abundant in Asp, Glu, Lys, Leu, Val and Ala. $IC_{50}\;(amounts\;of\;inhibitors\;needed\;for\;50\%\;inhibition)$ of the active fraction of the hydrolysates obtained from the treatment of complex enzyme and bromelain was 90 and $130 {\mu}g,$ respectively.