• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.2
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• pp.149-159
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• 1998

To utilize the oyster shell containing a lot of calcium, we investigated the bioavailability of calcium compounds from oyster shell. First, calcium oxide was prepared by burning of oyster shell at $1200^{\circ}C$. Its purity was approximately $98.5\%$. Calcium compounds, $CaCl_2$, and $CaHPO_4$, from the calcium oxide were prepared by chemical reaction. Effect on calcium absorption by the calcium compounds from oyster shell was improved using fish skin gelatin peptides.(FSGP), which was prepared by enzymatic hydrolysis of fish skin gelatin for 4hr with tuna pyloric caeca crude enzyme (TPCCE). in vitro experiment, calcium absorption by addition of FSGP in a mixture solution of calcium and phosphate was higher approximately $70\%$ than that by control. in vivo using calcium deficient rats, a group taken the diets with $3\%$ FSGP and $CaHPO_4$ was significantly improved amount of calcium and ash in femur and strength of femur. These results suggest that calcium compounds from oyster shell and FSGP could be used as an effective dietary calcium source.

• Korean Journal of Microbiology
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• v.52 no.3
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• pp.336-343
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• 2016

A mannanase gene was cloned into Escherichia coli from Cellulosimicrobium sp. YB-43, which had been found to produce two kinds of mannanase, and sequenced completely. This mannanase gene, designated manB, consisted of 1,284 nucleotides encoding a polypeptide of 427 amino acid residues. Based on the deduced amino acid sequence, the ManB was identified to be a modular enzyme including two carbohydrate binding domains besides the catalytic domain, which was highly homologous to mannanases belonging to the glycosyl hydrolase family 5. The N-terminal amino acid sequence of ManB, purified from a cell-free extract of the recombinant E. coli carrying a Cellulosimicrobium sp. YB-43 manB gene, has been determined as QGASAASDG, which was correctly corresponding to signal peptide predicted by SignalP4.1 server for Gram-negative bacteria. The purified ManB had a pH optimum for its activity at pH 6.5~7.0 and a temperature optimum at $55^{\circ}C$. The enzyme was active on locust bean gum (LBG), konjac and guar gum, while it did not exhibit activity towards carboxymethylcellulose, xylan, starch, and para-nitrophenyl-${\beta}$-mannopyranoside. The activity of enzyme was inhibited very slightly by $Mg^{2+}$, $K^+$, and $Na^+$, and significantly inhibited by $Cu^{2+}$, $Zn^{2+}$, $Mn^{2+}$, and SDS. The enzyme could hydrolyze mannooligosaccharides larger than mannobiose, which was the most predominant product resulting from the ManB hydrolysis for mannooligosaccharides and LBG.

• Food Science and Preservation
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• v.13 no.1
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• pp.88-94
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• 2006

This study was carried out to produce antimicrobial peptides from casein using various proteases. To examine whether the hydrolysis of casein would produce antimicrobial substance and the application as natural antimicrobial material, casein was hydrolyzed by five different proteases. The casein hydrolysate was fractionated with regenerated membrane filter (molecular weight cut-off 30,000 10,000 and 3,000) and antimicrobial activity was measured for each fraction. Antimicrobial activity appeared great in the fraction below 3,000 molecular weight The fraction was re-fractionated by high performance liquid chromatography and substance of main peak (retention time: 13.2 min) collected was used as a sample to measure antimicrobial activity. Among the casein hydrolysates produced by protease, antimicrobial activity was observed the greatest in hydrolysate treated with Aspergillus oryzae protease. The minimum inhibition concentrations of the Asp. oryzae protease hydrolysate were 1.0-1.5 mg/mL. This hydrolysate was a heat stable peptide since antimicrobial activity was maintained after treating with heat for 20 min at $121^{\circ}C$.

• Korean Journal of Microbiology
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• v.54 no.2
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• pp.126-135
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• 2018

The characteristics of enzyme and gene for mannanase B had been reported from Cellulosimicrobium sp. YB-43 producing some kind of mannanase. A gene coding for the enzyme, named mannanase C (ManC), was expected to be located downstream of the manB gene. The manC gene was cloned by polymerase chain reaction and sequenced completely. From this nucleotide sequence, ManC was identified to consist of 448 amino residues and contain a carbohydrate binding domain CBM2 besides a catalytic domain, which was homologous to mannanase belonging to the glycosyl hydrolase family 5. The catalytic domain of ManC showed the highest amino acid sequence similarity of 55% with the mannanases from Streptomyces sp. SirexAA-E (55.8%; 4FK9_A) and S. thermoluteus (57.6%; BAM62868). The His-tagged ManC (HtManC) lacking N-terminal signal peptide with hexahistidine at C-terminus was produced and purified from cell extract of recombinant Escherichia coli. The purified HtManC showed maximal activity at $65^{\circ}C$ and pH 7.5, with no significant change in its activity at pH range from 7.5 to 10. HtManC showed more active on konjac and locust bean gum (LBG) than guar gum and ivory nut mannan (ivory nut). Vmax and Km values of the HtManC for LBG were 68 U/mg and 0.45 mg/ml on the optimal condition, respectively. Mannobiose and mannotriose were observed on TLC as major products resulting from the HtManC hydrolysis of mannooligosacharides. In addition, mannobiose and mannose were commonly detected as the hydrolyzed products of LBG, konjac and ivory nut.

• Korean Journal of Food Science and Technology
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• v.46 no.2
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• pp.165-172
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• 2014

Mixed fermentation of cow milk was performed by sequential co-cultures with Bacillus subtilis and Lactococcus lactis. After a first fermentation step with B. subtilis for 6 h, the number of viable cells increased to $2.5{\times}10^8$ CFU/mL. The second fermentation step with L. lactis resulted in increased viable cells $1.09{\times}10^{10}$ CFU/mL for 3 days and increased acidity. However, the number of viable B. subtilis cells was decreased greatly to $5{\times}10^1$ CFU/mL following fermentation with L. lactis. Milk proteins were markedly hydrolyzed by the first fermentation after 2 h, and the second fermentation induced curd formation in milk. However, after 4 h, the first fermentation resulted in higher whey separation and 80 mg% tyrosine content. Gamma-aminobutyric acid (GABA) production was dependent upon the degree of protein hydrolysis by first fermentation. Second fermentation resulted in 0.14% GABA. The milk fermented by B. subtilis indicated the rough surface of yogurt depended upon the degree of protein hydrolysis. In conclusion, set-type yogurt was efficiently produced by co-culturing of milk, and fortifying with peptides, GABA, and probiotics.

• Korean Journal of Food Science and Technology
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• v.51 no.5
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• pp.473-479
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• 2019

Gryllus bimaculatus (GB) has recently been registered as a food variety in Korea. In the present study, we prepared protein hydrolysates from GB and evaluated their antioxidant capacity. Protein hydrolysates were prepared from dried GB using enzymatic hydrolysis using five different proteases, and protein hydrolysates showing high hydrolysis value (alcalase, flavourzyme, and neutrase) were separated further into fractions ${\leq}3kDa$ and then lyophilized. Based on $RC_{50}$ values of hydrolysates (${\leq}3kDa$) obtained from four different antioxidant analyses, the flavourzyme hydrolysates showed relatively high levels of antioxidant capacity among the three hydrolysates, and in particular, it showed considerably strong antioxidant activity in 2,2-diphenyl-1-picrylhydrazyl (DPPH) assays. The flavourzyme hydrolysate also significantly inhibited peroxidation of linoleic acid. These results suggest that protein hydrolysates from GB represent potential sources of natural antioxidants. Our current studies are focused on identification of active peptides from the flavourzyme hydrolysate.

• Korean Journal of Food Science and Technology
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• v.26 no.4
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• pp.436-441
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• 1994

To investigate the lowering effects of in vitro enzymatic hydrolysis by the treatment of chymotrypsin, trypsin, pancreatin, or protease from Aspergillus oryzae on the antigenicity of whey protein isolate (WPI) against rabbit anti ${\alpha}-LA$ antiserum, competitive inhibition ELISA (cELISA) and passive cutaneous anaphylaxis (PCA) test using guinea pig were performed. The results of cELISA showed that the monovalent antigenicity of the whey protein hydrolysates (WPH) to the antiserum was decreased to $10^{-2.5}-10^{-5.5}$ and less by the hydrolysis. The monovalent antigenicity of the WPH hydrolyzed by trypsin, or protease from Asp. nryzae was much lowered by the pretreatment of heat denaturation. The antigenicity of the WPH hydrolyzed by chymotrypsin, trypsin, or pancreatin was much lowered by the pretreatment of pepsin. Especially, the antigenicity of TDP (trypic hydrolysate with pretreatment of heat and pepsin) was found almost to be removed. However, there was not consistency between degree of hydrolysis(DH) and the monovalent antigenicity of the WPH. By the heterologous PCA it was found that all of the PGPH lost the polyvalent antigenicity regardless of the pretreatments although WPI and ${\alpha}-LA$ had the positive high antigenicity. The results suggested that the peptides derived from ${\alpha}-LA$ in WPH could bind specific antibodies but they could not induce allergy. Therefore, it was elucidated that the allergenicity of ${\alpha}-LA$ in whey protein could be destroyed easily by the enzymatic hydrolysis.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.4
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• pp.481-487
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• 1999

The optimal conditions of enzymatic hydrolysis for preparation of rapid salted and fermented anchovy sauce (SFAS) using various pretenses such as trypsin, chymotrypsin, crude enzyme from squid liver and viscera, Alcalase, Neutrase and Protamex were studied. SFAS prepared with squid viscera had higher level of VBN (173.6 mg/100 g) when stored for 70 days than other samples, and peroxide values were almost equal among all samples during fermentation period. Total amino acids and nonprotein nitrogenous compounds remarkably increased as SFAS treated with Alcalase or Protamex which exhibited higher the hydrolysis rate of $57\%$ at 60 day than others. The optimal pHs of trypsin, chymotryosin, Alcalase, Neutrase and Protamex on anchovy actomyosin were 7.5, 6.5, 6.5, 7.0 and 5.0, respectively. Optimal temperatures of trypsin, chymotryosin, Alcalase and Neutrase were 55, 45, 60 and $55^{\circ}C$, respectively. Otherwise, Protamex activity increased as temperature increased from 20 to $70^{\circ}C$. Protamex had higher $K_m$ (3.545) and $V_{max}$ value (2.688) than others. Protamex affected less by NaCl had $52.5\%$ activity at the fermentation condition of $20^{\circ}C$ and $25\%$ NaCl. Protamex appeared to be very effective for the hydrolysis of crude actomyosin from ancnovy.

• Microbiology and Biotechnology Letters
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• v.18 no.5
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• pp.496-500
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• 1990

When pepsin was used at a concentration of 8 mglml for hydrolysis of 0.02% casein, inhibitory activity of this inhibitor was proportional to a inhibitor concentration of 20 ${\mu}g$/ml, and fifty percent inhibition ($IC_{50}$) was observed to be 15 ${\mu}g$/ml. The inhibitor was pH-stable at pH range of 5-9 at $100^{\circ}C$ for 10 minutes and thermo-stable at pH 7.0 at $100^{\circ}C$ to give 100% activity for 20 minutes. The formation of pepsin-inhibitor complex was confirmed by sephadex 6-25 gel filtration and type of inhibition was determined as non-competitive inhibition by Lineweaver-Burk plot. The inhibitor strongly inhibited acid proteases such as pepsin and renin, and it was soluble in methanol very well. On TLC analysis of silicagel 60 using various sohent systems, the inhibitor gave a single spot at Rf range 0.4-0.6. From the result of IR spectrum and color reaction (Rydon-Smith, Biuret), this inhibitor was considered as peptide substance. Melting point and elemental contents were 220-$230^{\circ}C$, and C 50.61%-H 8.02%-N 9.34% (found), respectively.

• BMB Reports
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• v.30 no.1
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• pp.46-54
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• 1997

Alkaliphilic Bacillus sp. S-1 secretes a large amount (approximately 80% of total pullulanase activity) of an extracellular pullulanase (PUL-E). The pullulanase exists in two forms: a precursor form (PUL-I: $M_r$ 180,000), and a processed form (PUL-E: $M_r$ 140,000). Two forms were purified to homogeneity and their properties were compared. PUL-I was different in molecular weight, isoelectric point, $NH_2$-terminal amino acid sequence, and stabilities over pH and temperature ranges. The catalytic activities of PUL-I were also distinguishable in the $K_m$ and $V_{max}$ values for various substrates, and in the specific activity for pullulan hydrolysis. PUL-E showed 10-fold higher specific activities than PUL-I. However. PUL-I is immunologically identical to PUL-E, suggesting that PUL-I is initially synthesized and proteolytically processed to the mature form of PUL-E. Processing was inhibited by PMSF, but not by pepstatin, suggesting that some intracellular serine proteases could be responsible for processing of the PUL-I. PUL-I has a different conformational structure for antibody recognition from that of PUL-E. It is also postulated that the translocation of alkaline pullulanase(AP) in the bacterium possibly requires processing of the $NH_2$-terminal region of the AP protein. Processing of the precursor involves a conformational shift. resulting in a mature form. Therefore. precursor processing not only cleaves the signal peptide, but also induces conformational shift. allowing development of active form of the enzyme.