• Journal of Life Science
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• v.14 no.5
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• pp.752-760
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• 2004

The function of the [4Fe-4S] cluster containing iron (Fe-) protein in nitrogenase catalysis is to serve as the nucleotide-dependent electron donor to the MoFe protein which contains the sites for substrate binding and reduction. The ability of the Fe protein to function in this manner is dependent on its ability to adopt the appropriate conformation for productive interaction with the MoFe protein and on its ability to change redox potentials to provide the driving force required for electron transfer. The MgADP-bound (or off) conformational state of the nitrogenase Fe protein structure described reveals mechanisms for long-range communication from the nucleotide-binding sites to control affinity of association with the MoFe protein component. Two pathways, termed switches I and II, appear to be integral to this nucleotide signal transduction mechanism. In addition, the structure of the MgADP bound Fe protein provides the basis for the changes in the biophysical properties of the [4Fe-4S] observed when Fe protein binds nucleotides. The structures of the nitrogenase Fe protein with defined amino acid substitutions in the nucleotide dependent signal transduction pathways of the Switch I and Switch II have been determined by X-ray diffraction methods. These two pathways have been also implicated by site directed mutagenesis studies, structural analysis and analogies to other proteins that utilize similar nucleotide dependent signal transduction pathways. We have examined the validity of the assignment of these pathways in linking the signals generated by MgATP binding and hydrolysis to macromolecular complex formation and intermolecular electron transfer. The results provide a structural basis for the observed biophysical and biochemical properties of the Fe protein variants and interactions within the nitrogenase Fe protein-MoFe protein complex.

• Journal of Nutrition and Health
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• v.15 no.4
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• pp.258-267
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• 1982

This study was performed to investigate the effect of different levels of protein and iron in the diet upon Fe, Cu and Zn metabolism in rat during four weeks of growing period. Forty-five male weanling rats of Sprague-Dawley strain weighing $68.5{\pm}1.1g$ were divided into 9 groups and each group was given with one of the 9 different kinds of diets for four weeks. The three dietary protein levels used were 5, 20 and 40% and Fe levels 0, 35, and 350 ppms. The results obtained were summarized as following ; 1) Food intake and body weight gain in 20%(SP) and 40%(HP) dietary protein groups tended to be significantly higher than 5%(LP) protein groups. Protein efficiency ratio (PER) was higher in LP groups than in HP and SP groups. With dietary Fe levels, there were no significant differences among groups in food intake, body weight gain, and PER. 2) In LP groups, the Fe concentrations in liver, kidney, and hind limb muscle were higher than in SP and HP groups. Regarding with dietary protein levels, the liver Cu concentrations in LP groups were slightly higher, but the liver Zn concentrations were lower in LP groups. The Fe concentrations in liver and kidney tended to decrease with decrease in dietary Fe levels, but Cu and Zn concentrations showed no consistent tendency with dietary Fe levels. 3) The Fe, Cu and Zn concentrations in serum were not different from dietary treatments except that the serum Fe concentrations increased slightly in LP groups. 4) The Fe and Cu concentrations in urine tended to be higher in HP groups. Fecal Cu and Zn concentrations showed no significant differences in dietary protein or Fe levels, but the Fe concentrations tended to increase with increase in dietary Fe levels.

• Proceedings of the Korean Biophysical Society Conference
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• 2002.06b
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• pp.18-18
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• 2002

Nitrogenase, comprised of the MoFe and Fe proteins, catalyzes the reduction of dinitrogen to ammonia at ambient temperature and pressure. The MoFe protein contains two metal centers, the P-cluster (Fe8S7-8) and the FeMo-cofactor (Fe7S9：homocitrate), the substrate binding site. Despite the availability of the crystal structure of the MoFe protein, suprisingly little is known about the molecular details of catalysis at the active site, and no small-molecule substrate or inhibitor had ever been shown to directly interact with a protein-bound cluster of the functioning enzyme, until our electron-nuclear double resonance(ENDOR) study of CO-inhibited nitrogenase.(omitted)

• Applied Biological Chemistry
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• v.48 no.3
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• pp.189-200
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• 2005

Biological nitrogen fixation is an important process for academic and industrial aspects. This review will briefly compare industrial and biological nitrogen fixation and cover the characteristics of biological nitrogen fixation studied in Azotobacter vinelandii. Various organisms can carry out biological nitrogen fixation and recently the researches on the reaction mechanism were concentrated on the free-living microorganism, A. vinelandii. Nitrogen fixation, which transforms atmospheric $N_2$ into ammonia, is chemically a reduction reaction requiring electron donation. Nitrogenase, the biological nitrgen fixer, accepts electrons from biological electron donors, and transfers them to the active site, FeMo-cofactor, through $Fe_4S_4$ cluster in Fe protein and P-cluster in MoFe protein. The electron transport and the proton transport are very important processes in the nitrogenase catalysis to understand its reaction mechanism, and the interactions between FeMo-cofactor and nitrogen molecule are at the center of biological nitrogen fixation mechanism. Spectroscopic studies including protein X-ray crystallography, EPR and $M{\ddot{o}}ssbauer$, biochemical approaches including substrate and inhibitor interactions as well as site-directed mutation study, and chemical approach to synthesize the FeMo-cofactor model compounds were used for biological nitrogen fixation study. Recent research results from these area were presented, and finally, a new nitrogenase reaction mechanism will be proposed based on the various research results.

• Korean Journal of Food Science and Technology
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• v.25 no.1
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• pp.46-51
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• 1993

The inactivating effect of iron(II)-ascorbate complex (Fe-Asc) on various phages was previously reported. This paper describes the molecular target in the phage virion attacked by Fe-Asc. The effect of Fe-Asc on protein was investigated with bovine serum albumin and the structural protein of phage J1. There were no differences in the SDS-polyacrylamide gel electrophoresis (patterns of these two proteins when either they were treated) with Fe-Asc or not. Also, there were no changes in the amino acid composition and ultraviolet spectrum of the proteins. The effects of Fe-Asc on DNA was investigated with pUC18 DNA, M13mpB DNA and ${\lambda}$ DNA as well as DNA from phage J1. Fe-Asc caused initially nicking of the subsequently form of pUC18 DNA to yield the open circular form and then subsequently the linear form. Strand breaks were also confirmed with M13mp8 DNA and ${\lambda}$ DNA as well as J1 DNA. The results indicate that the strand breaks in phage DNA could be responsible for the inactivation of phages by Fe-Asc.

• Journal of Environmental Health Sciences
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• v.30 no.1
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• pp.29-40
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• 2004

This study was performed to investigate and assess the composition of mineral and macronutrient contents in Korean cow′s milk.48 individual farm raw milk, 10 plant raw milk and 29 market milk were collected from June to August in 2003. The minerals such as calcium(Ca), potassium(K), magnesium(Mg), sodium(Na), zinc(Zn), iron(Fe) and phosphorus(P) were determined by using atomic absorption spectrometer(AAS). The macronutrients such as fat, protein and lactose were tested by using IR spectrometer. The obtained analytical results of minerals(mg/100 g) and rnaetronutrients (％) are as follows：1. In case of raw cow′s milk ； Ca 113.56, K 144.09, Mg 10.86, Na 42.53, Zn 0.42, Fe 0.030, p 113.32, fat 3.85, protein 3.08, lactose 4.80,2. In case of market cow′s milk ; Ca 103.04, K 142.46, Mg 10.27, Na 43.21, Zn 0.40, Fe 0.034. p 97.30, fat 3.78, protein 3.05, lactose 4.70,3. In case of fortified market cow′s milk ; Ca 165.40, K 145.79, Mg 10.57. Na 42.55, Zn 0.57, Fe 0.414, p 94.68, fat 3.74, protein 3.08, lactose 4.68,4. In case of processed market cow′s milk ; Ca 134.72, K 142.74, Mg 10.33, Na 45.07, Zn 0.50, Fe 0.650, p 92.48, fat 3.72, protein 3.07, lactose 4.74. According to the group of market milk(milk, fortified market row′s milk, processed market cow′s milk), the mean concentration of Ca and Fe were significantly higher in fortified and processed milk than milk(p<0.05). There were no significant differences in macronutrient(fat, protein, lactose) and mineral contents between pasteurized milk and UHT(ultra high temperature) treated milk($\alpha$=0.05). The labeled "Nutritional Facts" of market milk were satisfied with "Labeling Standards for Livestock Products of Korea". The measured mean concentrations of Ca, Fe, Zn were generally higher than lower limit of labeled value(above 80% of labeled value). The mean concentration of sodium was lower than upper limit of labeled value(below 120％ of labeled value).

• Journal of the Korean Magnetic Resonance Society
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• v.24 no.3
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• pp.86-90
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• 2020

Iron-sulfur (Fe-S) clusters are one of the most ancient yet essential cofactors mediating various essential biological processes. In prokaryotes, Fe-S clusters are generated via several distinctive biogenesis mechanisms, among which the ISC (Iron-Sulfur Cluster) mechanism plays a house-keeping role to satisfy cellular needs for Fe-S clusters. The Escherichia coli ISC mechanism is maintained by several essential protein factors, whose structural characterization has been of great interest to reveal mechanistic details of the Fe-S cluster biogenesis mechanisms. In particular, nuclear magnetic resonance (NMR) spectroscopic approaches have contributed much to elucidate dynamic features not only in the structural states of the protein components but also in the interaction between them. The present minireview discusses recent advances in elucidating structural features of IscU, the key player in the E. coli ISC mechanism. IscU accommodates exceptional structural flexibility for its versatile activities, for which NMR spectroscopy was particularly successful. We expect that understanding to the structural diversity of IscU provides critical insight to appreciate functional versatility of the Fe-S cluster biogenesis mechanism.

• BMB Reports
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• v.41 no.1
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• pp.41-47
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• 2008

Fe65 is characterized as an adaptor precursor (APP) through its PID2 element, as well as with the other members of the APP protein family. With the serum- and glucocorticoid-induced kinase 1 (SGK1) substrate specificity information, we found that the putative site of phosphorylation in Fe65 by SGK1 is present on its $Ser^{566}$ residue in $^{560}CRVRFLSFLA^{569}$(X60469). Thus, we demonstrated that Fe65 and the fluorescein-labeled Fe65 peptide $FITC-^{560}CRVRFLSFLA^{569}$ are phosphorylated in vitro by SGK1. Phosphorylation of the $Ser^{566}$ residue was also demonstrated using a $Ser^{566}$ phospho-specific antibody. The phospho Fe65 was found mainly in the nucleus, while Fe65 S556A mutant was localized primarily to the cytoplasm. Therefore, these data suggest that SGK1 phosphorylates the $Ser^{566}$ residue of Fe65 and that this phosphorylation promotes the migration of Fe65 to the nucleus of the cell.

• Journal of Life Science
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• v.17 no.1 s.81
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• pp.18-23
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• 2007

Fe65, a neuron-specific adaptor protein, has two phosphotyrosine binding (PTB) domains. The second PTB (PTB2) domain interacts with intracellular domain fragment (AICD) of amyloid beta precursor protein (APP). Recent studies suggested that tile complex is composed of AICD and Fe65 transactivates genes that are responsible for neuronal cell death in Alzheimer's disease (AD). Therefore, a compound inhibiting the interaction between Fe65 and AICD can be a drug candidate to treat AD. However, it remains unclear how Fe65 recognizes AICD at a molecular level. Here, we report high-level production of the PTB2 domain of Fe65 in the baculovirus system. We found that the baculovirus system is an efficient method to obtain the Fe65 PTB2 domain, compared with the bacterial and mammalian expression systems. The purified recombinant protein was used for crystallization to determine its crystal structure helping to understand the molecular mechanism of Fe65-dependent signaling and to design its inhibitors.

• Journal of The Korean Society of Grassland and Forage Science
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• v.24 no.1
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• pp.1-10
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• 2004

This pot experiment was conducted to investigate the effects of combined micronutrient application($T_1$;control, $T_2$; Fe, $T_3$; Fe＋Mn, $T_4$; Fe＋Mn＋Cu, $T_5$ ; Fe＋Mn＋Cu＋Zn, $T_6$ ; Fe＋Mn＋Cu＋Zn＋Mo, $T_7$ ; Fe＋Mn＋Cu＋Zn＋Mo＋B) on forage performance of pure and mixed cultures of orchardgrass and white clover. The third part was concerned with the changes in the contents and yields of N-compounds (crude/pure protein and soluble N-compounds) in forages. The results obtained are summarized as follows: 1. The contents of N-compounds(crude/pure protein and soluble N-compounds) were generally different according to the forage species, whether it was a pure or mixed culture, and additional fertilization, especially N. In orchardgrass, these contents were relatively low at the $T_3$ and $T_6$ in both pure and mixed cultures. In white clover, these contents were relatively decreased by the $T_1$, $T_3$, and $T_6$ in mixed culture. 2. The treatments influenced relatively more on the yields of crude/pure protein than on the dry matter yields of forages, and this tendency was more significant in white clover than in orchardgrass. 3. In white clover, the great differences in the yields of crude protein by the treatments occurred especially in mixed culture and at 5th cut without no additional fertilization. In white clover, the positive effects of optimum treatments on the yields of crude protein seemed to be decreased by the additional fertilization, especially N. In mixed culture, the favorable growth of white clover by the optimum treatments tended to be positively related to the favorable contents and yields of N-compounds. The changes in the yields of pure protein were similar to the tendency of crude protein