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( Ah Reum Park ),( Joo Hee Hong ),( Jae Jin Kim ),( Jeong Jun Yoon ) 한국균학회 2012 Mycobiology Vol.40 No.3
A β-glucosidase from Penicillium italicum was purified with a specific activity of 61.8 U/mg, using a chromatography system. The native form of the enzyme was an 88.5-kDa tetramer with a molecular mass of 354 kDa. Optimum activity was observed at pH 4.5 and 60oC, and the half-lives were 1,737, 330, 34, and 1 hr at 50, 55, 60, and 65oC, respectively. Its activity was inhibited by 47% by 5 mM Ni2+. The enzyme exhibited hydrolytic activity for p-nitrophenyl-β-D-glucopyranoside (pNP-Glu), p-nitrophenyl-β-D-cellobioside, p-nitrophenyl-β-D-xyloside, and cellobiose, however, no activity was observed for p-nitrophenyl- β-D-lactopyranoside, p-nitrophenyl-β-D-galactopyranoside, carboxymetyl cellulose, xylan, and cellulose, indicating that the enzyme was a β-glucosidase. The kcat/Km (s-1 mM-1) values for pNP-Glu and cellobiose were 15,770.4 mM and 6,361.4 mM, respectively. These values were the highest reported for β-glucosidases. Non-competitive inhibition of the enzyme by both glucose (Ki = 8.9 mM) and glucono-δ-lactone (Ki = 11.3 mM) was observed when pNP-Glu was used as the substrate. This is the first report of non-competitive inhibition of β-glucosidase by glucose and glucono-δ-lactone.
Thermal Inactivation of Sodium-Habituated Staphylococcus aureus in Ready-to-Heat Sauces
Ah Reum Park,Jin Hee Lee,Sook Jin Jeong,In Gyun Hwang,Soon Ho Lee,Joon Il Cho,Yo Han Yoon 한국축산식품학회 2012 한국축산식품학회지 Vol.32 No.6
The objective of this study was to evaluate the effect of sodium habituation on thermal resistance of Staphylococcus aureus in various ready-to-heat (RTH) sauces. The strain mixture of S. aureus strains KACC10768, KACC10778, KACC11596, KACC13236 and NCCP10862 was habituated up to 9% of NaCl. The inocula of NaCl-habituated and nonhabituated S. aureus were inoculated in 5 g portions of pork cutlet, meat and Carbonara sauces at 7 Log CFU/g, and the samples were vortexed vigorously. The inoculated samples were then exposed to 60 and 70oC in a water-bath, and survivals of total bacteria and S. aureus were enumerated on tryptic soy agar and mannitol salt agar, respectively, every 30 min for 120 min. At 60oC, the cell counts of total bacteria and the significant difference in survivals between sodium-habituated and non-habituated S. aureus were observed only in the Carbonara sauce; the tailing effect, which is the period of no reduction of bacterial cell counts, was observed in pork cutlet, meat and Carbonara sauces subjected to 60oC. At 70oC, total bacterial populations and sodium-habituated and non-habituated S. aureus cell counts in meat and Carbonara sauce also significantly decreased (p
( Ah Reum Park ),( Jeong Hoon Park ),( Hye Jin Ahn ),( Ji Yeon Jang ),( Byung Jo Yu ),( Byung Hwan Um ),( Jeong Jun Yoon ) 한국균학회 2015 韓國菌學會誌 Vol.43 No.1
β-Glucosidase, which hydrolyzes cellobiose into two glucoses, plays an important role in the process of saccharification of the lignocellulosic biomass. In this study, we optimized the activity of β-glucosidase of brown-rot fungus Fomitopsis pinicola KCTC 6208 using the response surface methodology (RSM) with various concentrations of glucose, yeast extract and ascorbic acid, which are the most significant nutrients for activity of β-glucosidase. The highest activity of β-glucosidase was achieved 3.02% of glucose, 4.35% of yeast extract, and 7.41% ascorbic acid where ascorbic acid was most effective. The maximum activity of β-glucosidase predicted by the RSM was 15.34 U/mg, which was similar to the experimental value 14.90 U/mg at the 16th day of incubation. This optimized activity of β-glucosidase was 23.6 times higher than the preliminary activity value, 0.63 U/mg, and was also much higher than previous values reported in other fungi strains. Therefore, a simplified medium supplemented with a cheap vitamin source, such as ascorbic acid, could be a cost effective mean of increasing β-glucosidase activity.
Effect of genetic background differences between FVB and C57BL/6 mice in SARS-CoV-2 infection
Ah-Reum Kang,Hyun Ah Noh,Jae Hyung Son,Sun-Min Seo,Ji-Hun Lee,Na-Won Kim,Eun-Seon Yoo,Han-Bi Jeong,Da In On,Ji Yun Jang,Jun-Won Yun,Jun Won Park,Kang-Seuk Choi,Ho-Young Lee,Jun-Young Seo,Ki Taek Nam,J 한국실험동물학회 2022 한국실험동물학회 학술발표대회 논문집 Vol.2022 No.7
Biosynthesis of Glycosylated Derivatives of Tylosin in Streptomyces venezuelae
( Ah Reum Han ),( Sung Ryeol Park ),( Je Won Park ),( Eun Yeol Lee ),( Dong Myung Kim ),( Byung Gee Kim ),( Yeo Joon Yoon ) 한국미생물 · 생명공학회 2011 Journal of microbiology and biotechnology Vol.21 No.6
Streptomyces venezuelae YJ028, bearing a deletion of the entire biosynthetic gene cluster encoding the pikromycin polyketide synthases and desosamine biosynthetic enzymes, was used as a bioconversion system for combinatorial biosynthesis of glycosylated derivatives of tylosin. Two engineered deoxysugar biosynthetic pathways for the biosynthesis of TDP-3-O-demethyl-D-chalcose or TDP-Lrhamnose in conjunction with the glycosyltransferaseauxiliary protein pair DesVII/DesVIII were expressed in a S. venezuelae YJ028 mutant strain. Supplementation of each mutant strain capable of producing TDP-3-O-demethyl- D-chalcose or TDP-L-rhamnose with tylosin aglycone tylactone resulted in the production of the 3-O-demethyl- D-chalcose, D-quinovose, or L-rhamnose-glycosylated tylactone.
Park, Ah Reum,Park, Jeong-Hoon,Ahn, Hye-Jin,Jang, Ji Yeon,Yu, Byung Jo,Um, Byung-Hwan,Yoon, Jeong-Jun The Korean Society of Mycology 2015 Mycobiology Vol.43 No.1
${\beta}$-Glucosidase, which hydrolyzes cellobiose into two glucoses, plays an important role in the process of saccharification of the lignocellulosic biomass. In this study, we optimized the activity of ${\beta}$-glucosidase of brown-rot fungus Fomitopsis pinicola KCTC 6208 using the response surface methodology (RSM) with various concentrations of glucose, yeast extract and ascorbic acid, which are the most significant nutrients for activity of ${\beta}$-glucosidase. The highest activity of ${\beta}$-glucosidase was achieved 3.02% of glucose, 4.35% of yeast extract, and 7.41% ascorbic acid where ascorbic acid was most effective. The maximum activity of ${\beta}$-glucosidase predicted by the RSM was 15.34 U/mg, which was similar to the experimental value 14.90 U/mg at the 16th day of incubation. This optimized activity of ${\beta}$-glucosidase was 23.6 times higher than the preliminary activity value, 0.63 U/mg, and was also much higher than previous values reported in other fungi strains. Therefore, a simplified medium supplemented with a cheap vitamin source, such as ascorbic acid, could be a cost effective mean of increasing ${\beta}$-glucosidase activity.