• Korean Journal of Microbiology
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• v.27 no.1
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• pp.43-47
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• 1989

Characteristics and roles of protease released during the germination of Dictyostelium discoideum spores were investigated. When geat activated, the spores germinated, progressively releasing the protease into the extracellular medium. The protease activity exhibited high at pH 2.5. When cyclogeximide was added to culture, complete germination (emergence) and protease release were stopped. Addition of purified nonspecific protease to culture speeded up germination. These results suggest that excreted protease may play a role in removal of the spore wall.

• Korean Journal of Microbiology
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• v.45 no.4
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• pp.291-299
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• 2009

To elucidate HtrA3's functional roles in the HtrA3 mediated cellular processes, it is necessary to investigate its biochemical characteristics. In the present study, we constructed the plasmids encoding putative mature HtrA3 proteins (M1-HtrA3 and M2-HtrA3) based on the putative maturation sites of highly homologous HtrA1 and mouse HtrA3. We used the pGEX bacterial expression system to develop a simple and rapid purification for the recombinant HtrA3 protein. Although yields of the mature HtrA3 proteins were slightly low as 10~50 ${\mu}g$/L, the amounts and purity of M1- and M2-HtrA3 were enough to investigate their proteolytic activities. The putative mature HtrA3 proteins have proteolytic activity which could cleave $\beta$-casein as an exogenous substrate. We compared the proteolytic activity between the HtrA family, HtrA1, HtrA2, and HtrA3. The cleavage activity of HtrA3 and HtrA2 were 2 folds higher than that of HtrA1, respectively. Our study provides a method for generating useful reagents to identify natural substrates of HtrA3 in the further studies.

• Journal of the East Asian Society of Dietary Life
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• v.26 no.2
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• pp.163-170
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• 2016

This study investigated the quality characteristics of doenjang prepared with different Bacillus strains (Bacillus subtilis KACC 15935 and Bacillus subtilis HJ18-9). Changes in enzyme activities (protease, cellulase, and ${\alpha}-amylase$), amino-type nitrogen and ammonia-type nitrogen contents, and reducing sugar were investigated during the fermentation period. Enzymes such as protease, cellulase, and ${\alpha}-amylase$ play important roles in the composition of nutrients, as well as in the flavor and taste of doenjang. After 60 days of fermentation, protease activities in control doenjang, and doenjang fermented with B. subtilis KACC 15935, and B. subtilis HJ18-9 increased significantly up to $382.58{\pm}4.02$, $342.58{\pm}7.94$, and $392.58{\pm}1.91unit/g$, respectively (p<0.05). At the beginning of fermentation, protease activities were in the range of 156.88~182.71 unit/g. Cellulase and ${\alpha}-amylase$ activities of doenjang in HJ18-9 were higher than those in other samples. After fermentation, amino-type nitrogen in doenjang fermented with control, B. subtilis KACC 15935, and B. subtilis HJ18-9 increased significantly up to $143.25{\pm}1.62$, $141.86{\pm}2.14$, and $150.23{\pm}1.62mg%$, respectively (p<0.05). These results suggest that B. subtilis HJ18-9 is a suitable starter for the preparation of doenjang.

• International Journal of Industrial Entomology and Biomaterials
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• v.45 no.2
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• pp.43-48
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• 2022

Bombyx mori is a representative industrial insect and is used in silk production. Additionally, it serves as an insect model in molecular studies. To date, various molecular studies on its physiological characteristics, including the innate immune response and cuticular melanization, have been conducted. The melanization, including cuticular melanization, in insects is controlled by the prophenoloxidase-activating system, which is also involved in their innate immune response. In this review, to better understand the molecular mechanisms underlying the prophenoloxidase-activating system in the silkworm, the roles of five biomolecules, namely tyrosine hydroxylase, prophenoloxidase-activating enzyme, phenoloxidase, serine protease homolog, and immulectin, are discussed.

• Parasites, Hosts and Diseases
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• v.60 no.2
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• pp.117-126
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• 2022

Cystatin, a cysteine protease inhibitor found in many parasites, plays important roles in immune evasion. This study analyzed the molecular characteristics of a cystatin from Fasciola hepatica (FhCystatin) and expressed recombinant FhCystatin (rFhcystatin) to investigate the immune modulatory effects on lipopolysaccharide-induced proliferation, migration, cytokine secretion, nitric oxide (NO) production, and apoptosis in mouse macrophages. The FhCystatin gene encoded 116 amino acids and contained a conserved cystatin-like domain. rFhCystatin significantly inhibited the activity of cathepsin B. rFhCystatin bound to the surface of mouse RAW264.7 cells, significantly inhibited cell proliferation and promoted apoptosis. Moreover, rFhCystatin inhibited the expression of cellular nitric oxide, interleukin-6, and tumor necrosis factor-α, and promoted the expression of transforming growth factor-β and interleukin-10. These results showed that FhCystatin played an important role in regulating the activity of mouse macrophages. Our findings provide new insights into mechanisms underlying the immune evasion and contribute to the exploration of potential targets for the development of new drug to control F. hepatica infection.