Journal of Microbiology

Jong-Il Kim

7 Articles

Rapid Propagational Interactions of Slow Binding Inhibitor with RecA Protein Occur on the Longer Nucleoprotein Filaments: Jong-Il Kim; J. Microbiol. 2010;48(1):71-76. Published online March 11, 2010; DOI: https://doi.org/10.1007/s12275-009-0306-4

Abstract PDF: RecA protein is a DNA-dependent ATPase. RecA protein-mediated ATP hydrolysis occurs throughout the filamentous nucleoprotein complexes of RecA and DNA. Nucleotide analog ATP[γS] may not act simply as a competitive inhibitor, leading to inhibition kinetic patterns that are informative. When a mixture of ATP and ATP[γS] is present at the beginning of reaction, a transient phase lasting several minutes is observed in which the system approaches the state characteristic of the new ATP/ATP[γS] ratio. This phase consists of a burst or lag in ATP hydrolysis, depending on whether ATP or ATP[γS] respectively, is added first. The transition phase reflects a slow conformational change in a RecA monomer or a general adjustment in the structure of RecA filaments. The RecA filaments formed on longer DNA cofactor were more sensitive, and respond more rapidly to ATP[γS] than on shorter DNA cofactors.

Analysis of Double Stranded DNA-dependent Activities of Deinococcus radiodurans RecA Protein: Jong-Il Kim; J. Microbiol. 2006;44(5):508-514.; DOI: https://doi.org/2447 [pii]

Abstract PDF: In this study, the double-stranded DNA-dependent activities of Deinococcus radiodurans RecA protein (Dr RecA) were characterized. The interactions of the Dr RecA protein with double-stranded DNA were determined, especially dsDNA-dependent ATP hydrolysis by the Dr RecA protein and the DNA strand exchange reaction, in which multiple branch points exist on a single RecA protein-DNA complex. A nucleotide cofactor (ATP or dATP ) was required for the Dr RecA protein binding to duplex DNA. In the presence of dATP, the nucleation step in the binding process occurred more rapidly than in the presence of ATP. Salts inhibited the binding of the Dr RecA protein to double-stranded DNA. Doublestranded DNA-dependent ATPase activities showed a different sensitivity to anion species. Glutamate had only a minimal effect on the double-stranded DNA-dependent ATPase activities, up to a concentration of 0.7 M. In the competition experiment for Dr RecA protein binding, the Dr RecA protein manifested a higher affinity to double-stranded DNA than was observed for single-stranded DNA.

Decomposition of Biological Macromolecules by Plasma Generated with Helium and Oxygen: Seong-Mi Kim , Jong-Il Kim; J. Microbiol. 2006;44(4):466-471.; DOI: https://doi.org/2403 [pii]

Abstract PDF: In this study, we attempted to characterize the biomolecular effects of an atmospheric pressure cold plasma (APCP) system which utilizes helium/oxygen (He/O2). APCP using He/O2 generates a low level of UV while generating reactive oxygen radicals which probably serve as the primary factor in sterilization; these reactive oxygen radicals have the advantage of being capable to access the interiors of the structures of microbial cells. The damaging effects of plasma exposure on polypeptides, DNA, and enzyme proteins in the cell were assessed usiing biochemical methods.

Characterization of Calcium-Activated Bifunctional Peptidase of the Psychrotrophic Bacillus cereus: Jong-Il Kim , Sun-Min Lee , Hyun-Joo Jung; J. Microbiol. 2005;43(3):237-243.; DOI: https://doi.org/2219 [pii]

Abstract PDF: The protease purified from Bacillus cereus JH108 has the function of leucine specific endopeptidase. When measured by hydrolysis of synthetic substrate (N-succinyl-Ala-Ala-Pro-Leu-p-nitroanilide), the enzyme activity exhibited optimal activity at pH 9.0, 60^oC. The endopeptidase activity was stimulated by Ca^+^+, Co^+^+, Mn^+^+, Mg^+^+, and Ni^+^+, and was inhibited by metal chelating agents such as EDTA, 1,10-phenanthroline, and EGTA. Addition of serine protease inhibitor, PMSF, resulted in the elimination of the activity. The endopeptidase activity was fully recovered from the inhibition of EDTA by the addition of 1 mM Ca^+^+, and was partially restored by Co^+^+ and Mn^+^+, indicating that the enzyme was stabilized and activated by divalent cations and has a serine residue at the active site. Addition of Ca^+^+ increased the pH and heat stability of endopeptidase activity. These results show that endopeptidase requires calcium ions for activity and/or stability. A Lineweaver-Burk plot analysis indicated that the K_m value of endopeptidase is 0.315 mM and V_max is 0.222 mmol of N-succinyl-Ala-Ala-Pro-Leu-p-nitroanilide per min. Bestatin was shown to act as a competitive inhibitor to the endopeptidase activity.

Characterization of Recombinant Drosophila melanogaster Myo-inositol-1-phosphate Synthase Expressed in Escherichia coli: Sang-Hee Park , Jong-Il Kim; J. Microbiol. 2004;42(1):20-24.; DOI: https://doi.org/2006 [pii]

Abstract PDF: Cloned myo-inositol-1-phpsphate synthase (INOS) of Drosophila melanogaster was expressed in Escherichia coli, and purified using a His affinity column. The purified INOS required NAD^+ for the conversion of glucose-6-phosphate to inositol-1-phosphate. The optimum pH for myo-inositol-1-phosphate synthase is 7.5, and the maximum activity was measured at 40^oC. The molecular weight of the native enzyme, as determined by gel filtration, was approximately M_r 271,000±15,000. A single subunit of approximately M_r 62,000±5,000 was detected upon SDS-polyacrylamide gel electrophoresis. The Michaelis (K_m) and dissociation constants for glucose-6-phosphate were 3.5 and 3.7 mM, whereas for the cofactor NAD^+ these were 0.42 and 0.4 mM, respectively.

Multicatalytic Alkaline Serine Protease from the Psychrotrophic Bacillus amyloliquefaciens S94: Eui-Sun Son , Jong-Il Kim; J. Microbiol. 2003;41(1):58-62.

Abstract PDF: An extracellular protease of Bacillus amyloliquefaciens S94 was purified to apparent homogeneity. The enzyme activity was strongly inhibited by general inhibitor for serine protease, PMSF, suggesting that the enzyme is a serine protease. The purified enzyme activity was inhibited by leucine peptidase inhibitor, bestatin, suggesting that the enzyme is a leucine endopeptidase. The maximum proteolytic activity against different protein substrates occurred at pH 10, 45℃ (protein substrate) and pH 8, 45℃ (synthetic substrate). The purified enzyme was specific in that it readily hydrolyzed substrates with Leu or Lys residues at P1 site. The protease had characteristics of a cold-adapted protein, which was more active for the hydrolysis of synthetic substrate in the range of 15℃ to 45℃, specially at low temperature.

Purification and Characterization of Caseinolytic Extracellular protease from Bacillus amyloliquefaciens S94: Eui-Sun Son , Jong-Il Kim; J. Microbiol. 2002;40(1):26-32.

Abstract PDF: From the culture supernatant of the psychrotrophic strain of Bacillus amyloliquefaciens an extracellular serine protease was purified to apparent homogeneity by successive purification steps using QAE-Sephadex, SP-Sephadex and Sephacryl S-100 column chromatography. The protease is monomeric, with a relative molecular mass of 23,000. It is inhibited by the serine protease inhibitor phenylmethylsulfonyl fluoride, but not by EDTA. The enzyme is most active at pH 9-10, and at 45 C, although it is unstable at 60 C.

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