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Park, Jung-Mi;Joo, Kwang-Jee
- Journal of the Korean Society of Food Science and Nutrition
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- v.11 no.3
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- pp.67-74
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- 1982
The effect of various pH levels, temperatures. organic acids, inorganic salts, metal ions on the stability of the anthocyanins pigment (pH 3.7) from the juice of raspberries were investigated. Initial absorption of total anthocyanin was decreased as pH increased from 1.0 to 7.0. Total amount of anthocyanin reached the highest at pH 3.7 and least at pH 7.0. The total anthocyanin content decreased rapidly with the increasing temperature. Many organic acids were found to enrich and stabilize the color density at 520nm in anthocyanin solution (pH 3.7). The hyperchromic effect of saturated n-carboxylic acid increased in the following order; formic acid> acetic acid>n-butyric acid>propionic acid. On the polycarboxylic acid, especially, malic acid showed 550$\sim$930% higher than control group. On the inorganic salts (0.5M), sodium perchlorate had the most hyperchromic effect and followed by sodium sulfate>sodium chloride>sodium phosphate, monobasic. Among the metal ions, both aluminium ion and cupric ion much more accelerated the anthocyanins degradation as compared with other metal ions.
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Park, Kyung-Mi;Park, Sang-Shin
- Journal of Microbiology and Biotechnology
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- v.18 no.4
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- pp.670-675
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- 2008
A laccase was isolated from the culture filtrate of the basidiomycete Fomitella fraxinea. The enzyme was purified to electrophoretical homogeneity using ammonium sulfate precipitation, anion-exchange chromatography, and gel-filtration chromatography. The enzyme was identified as a monomeric protein with a molecular mass of 47 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and gel-filtration chromatography, and had an isoelectric point of 3.8. The N-terminal amino acid sequence for the enzyme was ATXSNXKTLAAD, which had a very low similarity to the sequences previously reported for laccases from other basidiomycetes. The optimum pH and temperature for 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) were 3.0 and $70^{\circ}C$, respectively. The enzyme also showed a much higher level of specific activity for ABTS and 2,6-dimethoxyphenol (DMP), where the $K_m$ values of the enzyme for ABTS and 2,6-DMP were 270 and $426{\mu}M$, respectively, and the $V_{max}$ values were 876 and $433.3{\mu}M/min$, respectively. The laccase activity was completely inhibited by L-cysteine, dithiothreitol (DTT), and sodium azide, significantly inhibited by $Ni^+,\;Mn^{2+}$, and $Ba^{2+}$, and slightly stimulated by $K^+$ and $Ca^{2+}$.
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Park, Jeen-Woo;Park, Hee-Sae
- BMB Reports
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- v.31 no.3
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- pp.227-232
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- 1998
The leukocyte NADPH oxidase of neutrophils is a membrane-bound enzyme that catalyzes the production of $O_2^-$ from oxygen using NADPH as an electron donor. Dormant in resting neutrophils, the enzyme acquires catalytic activity when the cells are exposed to appropriate stimuli. During activation, the cytosolic oxidase components $p47^{phox}$ and $p67^{phox}$ migrate to the plasma membrane, where they associate with cytochrome $b_{558}$, a membrane-bound flavohemoprotein, to assemble the active oxidase. The oxidase can be activated in a cell-free system; the activating agent usually employed is an anionic amphiphile such as sodium dodecyl sulfate (SDS). Because $p47^{phox}$ can translocate by itself during activation, the conformational change in $p47^{phox}$ may be responsible for the activation of NADPH oxidase. We show here that the treatment of $p47^{phox}$ with SDS leads to an increase in the reactivity of the sutbydryl group of cysteines toward N-ethylmaleimide, indicating that the conformational change occurs when $p47^{phox}$ is exposed to SDS. We propose that this change in conformation results in the appearance of a binding site through which $p47^{phox}$ interacts with cytochrome $b_{558}$during the activation process.
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배경숙;나종욱;강사욱;홍순우;하영칠;이계준
- Korean Journal of Microbiology
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- v.24 no.2
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- pp.106-112
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- 1986
The large plasmid (about 180 megadaltons) was isolated from the aquatic strain of Pseudomonas which was found to degrade salicylate. It was found that the plasmid could be isolated under gentle conditions in comparison with other methods. The yield of covalently closed circular DNA was enganced by heat treatment at $55^{\circ}C$ after denaturing the chromosomal DNA with alkaline sodium dodecyl sulfate (pH 12.45), and the plasmid DNA was selectively concentrated by utilizing 10% polyethylene glycol as final concentration. It was also found that the cured strains with mitomycin C did not show any growth on the medium containing salicylat6e, therefore, it was concluded that the plasmid might play and important role on the salicylate degradation.
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