• Journal of Nutrition and Health
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• v.14 no.3
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• pp.124-128
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• 1981

This study was carried out to understand the activity of pepsin, the proteolytic enzyme, to octapeptide (angiotensin II) in the presence of various synthetic antioxidants as food additives. 1) Dibutyl hydroxy toluene, butyl hydroxyanisole and ethyl protocathechuate did not influence the inhibitory activity of pepsin an the octapeptide as a substrate, but sodium-L-ascorbate inhibited pepsin activity at above 100ppm. However sodium L-ascorbate was completely removed after 30 minutes. 2) Pepsin brought about a quick break up the octapeptide, Asp-Arg-Val-Tyr-Ile-His-Gly-Phe, by splitting the Gly-Phe and Val-Tyr bond. 3) The melting point of synthetized octapeptide was $209-212^{\circ}C$, chemical formula and molecula weight were $C_{43}H_{65}N_{13}O_{12}{\cdot}CH_3COOH{\cdot}H_2O$ and 956.05, respectively. 4) The amino acid mole ratio of synthetized octapeptide by acid hydrolysis were Asp:0.98, Arg: 1.02, Val: 1.00. Tyr: 0.95, Ile: 1.00, His: 1.03, Gly: 0.96, Phe: 1.00.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.2
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• pp.550-555
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• 2008

An efficient production method of spirulina extract was developed by enzymatic treatment using proteolytic enzymes. The suitable dosage of Tunicase, a cell lytic enzyme, was used to be 2.0% (w/w). To maximize solid recovery and spirulina extraction (SE) index, which indicates nucleic acid-related substances content, the dosage of Alcalase, commercially available pretense, was found to be 1.0% (w/w). By simultaneous treatments using optimal dosages of Tunicase and Alcalase, the highest SE index and solid recovery were obtained. The SE index and solid recovery of simultaneous treatments were notably enhanced by 100% ($11.4%\;{\rightarrow}\;22.8%$) and 56% ($45.2%\;{\rightarrow}\;70.7%$), respectively, than those of the non-treated extracts.

• Molecules and Cells
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• v.23 no.2
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• pp.252-257
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• 2007

Escherichia coli HslVU is an ATP-dependent protease consisting of two heat shock proteins, the HslU ATPase and HslV peptidase. In the reconstituted enzyme, HslU stimulates the proteolytic activity of HslV by one to two orders of magnitude, while HslV increases the rate of ATP hydrolysis by HslU several-fold. Here we show that HslV alone can efficiently degrade certain unfolded proteins, such as unfolded lactalbumin and lysozyme prepared by complete reduction of disulfide bonds, but not their native forms. Furthermore, HslV alone cleaved a lactalbumin fragment sandwiched by two thioredoxin molecules, indicating that it can hydrolyze the internal peptide bonds of lactalbumin. Surprisingly, ATP inhibited the degradation of unfolded proteins by HslV. This inhibitory effect of ATP was markedly diminished by substitution of the Arg86 residue located in the apical pore of HslV with Gly, suggesting that interaction of ATP with the Arg residue blocks access of unfolded proteins to the proteolytic chamber of HslV. These results suggest that uncomplexed HslV is inactive under normal conditions, but may can degrade unfolded proteins when the ATP level is low, as it is during carbon starvation.

• Microbiology and Biotechnology Letters
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• v.21 no.1
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• pp.30-35
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• 1993

Clp is a relatively abundant ATP-dependent protease found in E. coli. Its specific activity was proportional to the concentration of the limiting amount of Clp A and an excess amount of Clp P, and vice versa. Clp A has an intrinsic ATPase activity that is stimulated by casein, and contains a second site for binding A TP, in addition to the ATPase site. The modification of sulfhydryl groups in Clp A with reagents which have bulky groups such as N-phenylmaleimide led to nullifying both ATPase and protease activity. The same sites were modified by sulfhydryl reagents. It seems that the sulfhydryl groups of Clp A are not directly involved in catalysis. Since non-hydrolyzable analogs of ATP do not activate Clp, ATP hydrolysis may be essential for the proteolytic activity of Clp protease. Clp A and Clp P did not associate in the absence of nucleotide. The results suggest that the activity of the proteolytic component, Clp P, is regulated by the A TP-dependent cycling of Clp A between the activator form and the non-activator form.

• Korean Journal of Food Science and Technology
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• v.27 no.5
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• pp.708-715
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• 1995

Effect of enzymatic modification with pepsin, papain and trypsin was studied on functional properties of isolated sesame meal protein hydrolysates. Solubility of protein hydrolysates distinctively increased from 2% to $53{\sim}94%$ at pH 4. Emulsifying properties showed marked increase 6 fold and 4.5 fold at degree of 10%, 20% hydrolysis by trypsin and degree of 10% hydrolysis by papain. The emulsion stability of the protein was unstable by heat treatment for 30 min. at $80^{\circ}C$. Foaming properties were also enhanced by enzymatic hydrolysis except at degree of 30% hydrolysis. Bulk density and water absorption of protein with trypsin and papain decreased about 0.1 g/ml and $0.3{\sim}0.7\;ml/g$, but oil absorption was increased about 1 ml/g.

• Food Science of Animal Resources
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• v.34 no.3
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• pp.362-371
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• 2014

This study utilized commercially available proteolytic enzymes to prepare egg-white protein hydrolysates (EPHs) with different degrees of hydrolysis. The antioxidant effect and functionalities of the resultant products were then investigated. Treatment with Neutrase yielded the most ${\alpha}$-amino groups (6.52 mg/mL). Alcalase, Flavourzyme, Protamex, and Ficin showed similar degrees of ${\alpha}$-amino group liberation (3.19-3.62 mg/mL). Neutrase treatment also resulted in the highest degree of hydrolysis (23.4%). Alcalase and Ficin treatment resulted in similar degrees of hydrolysis. All hydrolysates, except for the Flavourzyme hydrolysate, had greater radical scavenging activity than the control. The Neutrase hydrolysate showed the highest 2,2-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging activity ($IC_{50}=3.6mg/mL$). Therefore, Neutrase was identified as the optimal enzyme for hydrolyzing egg-white protein to yield antioxidant peptides. During Neutrase hydrolysis, the reaction rate was rapid over the first 4 h, and then subsequently declined. The $IC_{50}$ value was lowest after the first hour (2.99 mg/mL). The emulsifying activity index (EAI) of EPH treated with Neutrase decreased, as the pH decreased. The EPH foaming capacity was maximal at pH 3.6, and decreased at an alkaline pH. Digestion resulted in significantly higher 1,1-diphenyl-2-picrylhydrazyl (DPPH) and ABTS radical scavenging activity. The active peptides released from egg-white protein showed antioxidative activities on ABTS and DHHP radical. Thus, this approach may be useful for the preparation of potent antioxidant products.

• Food Science of Animal Resources
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• v.37 no.1
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• pp.62-70
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• 2017

The aim of this study was identifying a suitable food grade enzymes to hydrolyze whey protein concentrates (WPCs), to give the highest bioactivity. WPCs from ultrafiltration retentate were adjusted to 35% protein (WPC-35) and hydrolyzed by enzymes, alcalase, ${\alpha}-chymotrypsin$, pepsin, protease M, protease S, and trypsin at different hydrolysis times (0, 0.5, 1, 2, 3, 4, and 5 h). These 36 types of hydrolysates were analyzed for their prominent peptides ${\beta}-lactoglobulin$ (${\beta}-Lg$) and ${\alpha}-lactalbumin$ (${\alpha}-La$), to identify the proteolytic activity of each enzyme. Protease S showed the highest proteolytic activity and angiotensin converting enzyme inhibitory activity of IC50, 0.099 mg/mL (91.55%) while trypsin showed the weakest effect. Antihypertensive and antioxidative peptides associated with ${\beta}-Lg$ hydrolysates were identified in WPC-35 hydrolysates (WPH-35) that hydrolyzed by the enzymes, trypsin and protease S. WPH-35 treated with protease S in 0.5 h, responded positively to usage as a bioactive component in different applications of pharmaceutical or related industries.

• Food Science of Animal Resources
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• v.43 no.1
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• pp.46-60
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• 2023

Slaughterhouse blood is a by-product of animal slaughter that can be a good source of animal protein. This research purposed to examine the functional qualities of the blood plasma from Hanwoo cattle, black goat, and their hydrolysates. Part of the plasma was hydrolyzed with proteolytic enzymes (Bacillus protease, papain, thermolysin, elastase, and α-chymotrypsin) to yield bioactive peptides under optimum conditions. The levels of hydrolysates were evaluated by 15% sodium dodecyl sulfate polyacrylamide gel electrophoresis. The antioxidant, metal-chelating, and angiotensin I-converting enzyme (ACE) inhibitory properties of intact blood plasma and selected hydrolysates were investigated. Accordingly, two plasma hydrolysates by protease (pH 6.5/55℃/3 h) and thermolysin (pH 7.5/37℃/3-6 h) were selected for analysis of their functional properties. In the oil model system, only goat blood plasma had lower levels of thiobarbituric acid reactive substances than the control. The diphenyl picrylhydrazyl radical scavenging activity was higher in cattle and goat plasma than in proteolytic hydrolysates. Ironchelating activities increased after proteolytic degradation except for protease-treated cattle blood. Copper-chelating activity was excellent in all test samples except for the original bovine plasma. As for ACE inhibition, only non-hydrolyzed goat plasma and its hydrolysates by thermolysin showed ACE inhibitory activity (9.86±5.03% and 21.77±3.74%). In conclusion, goat plasma without hydrolyzation and its hydrolysates can be a good source of bioactive compounds with functional characteristics, whereas cattle plasma has a relatively low value. Further studies on the molecular structure of these compounds are needed with more suitable enzyme combinations.

• Food Science and Preservation
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• v.13 no.1
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• pp.71-76
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• 2006

We monitored the characteristics of soybean hydrolysate prepared under various hydrolysis condition using response surface methodology. The yield was affected by protease content but 1be effect of hydrolysis time to yield gradually increased at over $0.4\%$ of protease, while the $R^2$ of polynomial equation was 0.978 (p<0.01). The soluble solid enlarged by increase of both variables and the $R^2$ of polynomial equation was 0.954 (p<0.01). The degree of hydrolysis was affected by protease content at low (under $0.4\%$) protease and maximized at $0.57\%$ protease and 5.49 hrs. The $R^2$ of polynomial equation for the degree of hydrolysis was 0.916 (P<0.05). The calcium intolerance capacity showed similar pattern like yield but the effect of hydrolysis time was rapidly increased at over $0.4\%$ protease. The $R^2$ of polynomial equation for calcium intolerance capacity was 0.932 (p<0.05). The total phenolic compounds increased in proportion to protease content and hydrolysis time, while the $R^2$ of polynomial equation was 0.920 (p<0.05). According to the results of this study, the optimal conditions for soybean hydrolysis were predicted to be $0.51\~0.66\%$ of protease and $6.5\~9.0\;hrs$, and the predicted values and actual values of each response variable were similar to each other when the hydrolysis was performed at a random point within the optimal range.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.12 no.3
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• pp.143-153
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• 1979

A study on tile processing of liquefied fish protein with a long self life and good solubility has been carried out for the effective utilization of sardine. The whole sadine was chopped, homogenized with same amount of water and then hydrolyzed by the addition of commercial proteolytic enzyme. The hydrolysate was centrifuged and the supernatant was decolorized with active carbon, desodorized by azeotropic distillation with toluene, xylene and cyclohexane. The liquefied sardine protein was then concentrated by rotary vacuum evaporator with the addition of starch. The use of $0.2\%$ commercial proteolytic enzyme to the weight of the whole sardine showed the optimum hydrolysis ratio at $55^{\circ}C$ for 4 hours. The liquefied sardine protein could be decolorized and also desodorized by the treatment with $15\%$ active carl]on at room temperature for 30 minuted. In the view point of lipid concentration and the solubility of the product, the liquefied sardine protein prepared by enzymic hydrolysis from the sardine protein concentrate was better than that prepared by enzymic hydrolysis from the whole sardine and sardine protein concentrate.