• Journal of the Korean Society of Food Science and Nutrition
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• v.35 no.9
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• pp.1166-1171
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• 2006

This study was performed to investigate the effect of silk protein hydrolysates on blood glucose in diabetic mice (C57BL/KsJ db/db). The silk protein hydrolysates hydrolyzed by protease contains 87.52% of peptides of which molecular weight was below 2,000 dalton. The content of free amino acids was 14.80 g/100 g silk protein hydrolysates and major free amino acids were Pro, Thr, Arg and Ala. Silk protein hydrolysates were administered to the animals for 9 weeks at doses of 0.2, 0.5% and 0.8% solution. The body weight increase in the 0.5 and 0.8% fed groups were higher than control group. Food and water intake in the silk protein hydrolysates fed groups were lower than control group. The weight of liver was not different among groups, while the weight of kidney in control group was higher than silk protein hydrolysates fed groups. The blood glucose level in silk protein hydrolysates fed groups was lower than control group. In the glucose tolerance test, the blood glucose level in control group was the highest at 15 minutes after glucose injection while those in silk protein hydrolysates fed groups were the highest at 30 minutes. Results in this study suggest that silk protein hydrolysates show hypoglycemic effect in C57BL/KsJ db/db mice.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.1
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• pp.194-199
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• 2009

An efficient production method of food-grade heamatococcus extract was developed based on stepwise enzymatic hydrolysis. In the first step, Haematococcus pluvialis cells hydrolysis carried out with commercially available exopeptidase(Flavourzyme) and endopeptidase (Alcalase), resulted in increased astaxanthin content. In the second step, proteolytic hydrolyzed H. pluvialis cells treated with hetero-polysaccharides hydrolytic enzyme (Viscozyme). By two-stage treatments using Alcalase and Flavourzyme and Viscozyme, the highest astaxanthin content was obtained. The astaxanthin content was remarkably enhanced by 320% $(529{\mu}g/g\rightarrow2,256{\mu}g/g)$ than that of the non-treated extract. And then, antioxidative activities determined by DPPH method were increased with increasing the astaxanthin content in haematococcus extract prepared by enzymatic hydrolysis.

• Journal of Life Science
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• v.22 no.1
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• pp.7-15
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• 2012

A polyguluronate-specific lyase from Streptomyces sp. strain M3 has been previously cloned and characterized. In this study, the M3 alginate lyase gene in the pColdI vector was mutated by site-directed mutagenesis and random mutagenesis to enhance the alginate degrading activity. Six mutants were obtained: Ser25Arg, Phe99Leu, Asp142Asn, Val163Ala, Lys191Glu, and Gly194Cys. Phe99Leu and Lys191Glu mutants completely lost their alginate lyase activity, whereas the alginate degrading activity of Gly194Cys mutant increased by nearly 10 fold. The 3-D protein structure of M3 alginate lyase, which was constructed using the Swiss-Model automodeler, was also compared to the crystal structure of another alginate lyase. A mutated glycine residue was positioned between Gly193 and Tyr195 of the C-terminal conserved sequence, YFKAGXYXQ. A phenylalanine residue (at position 99) and a glycine residue (at position 194) mutated in this study were distant from the active site, but the degrading activity was strongly affected by their mutation.

• KSBB Journal
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• v.20 no.3
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• pp.215-219
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• 2005

Production of alkaline pretense by Bacillus clausii I-52 was optimized by experimental design methods. Among 7 medium components, three (wheat flour, sodium citrate, sodium carbonate) were selected as components affecting the pretense activity significantly by Plackett-Burman methods. Furthermore the ranges of effective concentrations were determined by Box-Behnken methods. The objective function describing the alkaline pretense production was obtained and optimum concentration of 3 components was determined by using response-surface methods (RSM). Theoretical maximum production was 74000 U/mL (Wheat flour: 0 g/L, Sodium citrate: 5 g/L, Sodium carbonate: 10 g/L). With the optimized medium composition, 92000 U/mL alkaline protease was produced experimentally, resulting in $90\%$ increase compared to before-optimization production (49000 U/mL).

• Korean Journal of Fisheries and Aquatic Sciences
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• v.19 no.6
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• pp.521-528
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• 1986

In this paper, proteolytic activity of the tissue extracts from the internal organs such as alimentary canal, pancreas, pyloric caeca, stomach, liver and spleen of mackerel, Scomber japonicus, and sardine, Sardinops melanosticta, was compared with each other under the optimum reaction condition. The proteinases distributed in alimentary canal, pancreas, pyloric caeca and spleen were active in alkaline pH range, but those in stomach were shown the activity in acid pH range, furthermore those in liver were exhibited the activity in acid, neutral and alkaline pH range. The proteinases distributed in the internal organs of both fish were stable at the heat treatment of $45^{\circ}C$ for 5 minutes. The proteinases from stomach and pyloric caeca of the two fish and those from pancreas of sardine were less stable than those from any other internal organs of both fish. Whereas the proteinases from spleen and neutral proteinases from liver were shown to be stable by the heat treatment at $55^{\circ}C$ for 5 minutes. The proteinases from pyloric caeca of both fish, and stomach, pancreas and spleen of mackerel were stable during the whole storage days at $5^{\circ}C$, but the other proteinases were slowly inactivated after 14 days of storage. The enzymes were seemed to be more stable in the storage at $-15^{\circ}C$ than at $5^{\circ}C$.

• The Korean Journal of Zoology
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• v.32 no.1
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• pp.48-54
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• 1989

Several proteolytic activities and the level of and-trypsin in neoplastic tissues of human cervix and liver were compared to those in normal tissues to examine if any correlation exists between malignant behavior of the tumors and the changes in overall proteolytic capacity. Proteolysis against casein and insulin in cervix tumor was increased to 2-to 3-fold while that in liver tumor was reduced to one-tenth to one-half. By contrast, the level of anti-trypsin in cervix tumor was lowered to nearly one-tenth of that in normal tissues while the level rose to about 2-fold in malignant tissues of liver. On the other hand, the activities of plasmin-like protease and plasminogen activator were enhanced 10-20% over the activities in normals. These results suggest that the changes in proteolytic capacity are at least in part due to outbalance in either of proteolytic or its inhibitory activity over the other and occur distinctively to each tumor systems for their malignant behavior.

• Korean Journal of Microbiology
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• v.27 no.3
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• pp.245-249
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• 1989

Extracellular proteases of Bacillus licheniformis were partially purified using ammonium sulfate fractionation and Sephadex G-75 gel filtration chromatography. The partial purification permited the weparation of two different protease activities, type I and type II. Protease type I is an enzyme with rather high protealytic activity toward dasein and was highly susceptible to organofluoride and EDTA inhibitions. It showed maximal proteolytic activity at pH 7.5 and was rapidly denatured at $71^{\circ}C$. Protease type II is a protease with relatively lower proteolytic activity than the type I. It was also inhibited by 10mM of EDTA and 1mM of PMSF by 30 min incubation. The enzyme showed maximal activity at pH 8.0 and was denatured relatively slowly at $71^{\circ}C$.

• Korean Journal of Microbiology
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• v.45 no.1
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• pp.69-73
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• 2009

Proteases are degradative enzymes which hydrolyze a peptide bond between amino acids and they are abundantly applied to commercial field. In order to investigate optimal medium compositions of carbon and nitrogen source for enzyme production, modified STY medium containing 0.15% yeast extract were used as basal medium. When galactose was used as carbon source, enzyme activity showed 1.3 higher than that of glucose. For nitrogen source addition of casamino acids to basal medium in place of tryptone showed lowest activity, whereas addition of malt extract showed maximal activity. The optimum temperature and pH of extracellular protease were found to be $35^{\circ}C$ an pH 8.5.

• Korean Journal of Microbiology
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• v.43 no.3
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• pp.222-226
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• 2007

Proteases are degradative enzymes which hydrolyze a peptide bond between amino acids and they are abundantly applied to commercial field. In order to screen new source of pretense, bacteria secreting extracellular pretense were isolated by enrichment culture from deep sea water samples of East Sea, Korea. A bacterium, named as HJ19, showed the best growth and the largest clear zone in plates supplemented skim milk at $30^{\circ}C$. The partial DNA sequence analysis of the 16S rRNA gene, phenotypic tests and morphology identified that this strain was In genus Micrococcus. The strain HJ19 could not grow at $10^{\circ}C$ but it started growth and showed pretense activity at $20^{\circ}C$. The optimal growth was at $37^{\circ}C$ and the maximal protease activity at $30^{\circ}C$ was about 480unit/ml.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.8
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• pp.1353-1358
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• 2004

This study was conducted to increase crude protein and reducing sugar contents in pollen extracts by proteases. Four commercial neutral proteases (Alcalase 2.4L, Protamex, Flavozyme and Protease A) and two alkaline proteases (Protease S and Protease P) were used to prepare acorn and Darae pollen extracts. Contents of moisture, ash, crude protein and crude fat of acorn pollen were 5.2%, 2.7%, 6.2% and 22.3%, respectively, while those of Darae pollen were 5.4%, 2.8%, 1.8% and 27.8%, respectively. Contents of crude protein and reducing sugar in pollen extracts were increased by proteases. Alcalase 2.4L was the most effective in increasing protein contents while Protease A in increasing reducing sugar contents. It is suggested the use of proteases is one of the potential methods for increasing the contents of crude protein and reducing sugar in preparation of pollen extracts.