• 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.

• The Korean Journal of Pesticide Science
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• v.5 no.3
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• pp.1-11
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• 2001

New technologies will have a large impact on the discovery of new herbicide site of action. Genomics, combinatorial chemistry, and bioinformatics help take advantage of serendipity through tile sequencing of huge numbers of genes or the synthesis of large numbers of chemical compounds. There are approximately $10^{30}\;to\;10^{50}$ possible molecules in molecular space of which only a fraction have been synthesized. Combining this potential with having access to 50,000 plant genes in the future elevates tile probability of discovering flew herbicidal site of actions. If 0.1, 1.0 or 10% of total genes in a typical plant are valid for herbicide target, a plant with 50,000 genes would provide about 50, 500, and 5,000 targets, respectively. However, only 11 herbicide targets have been identified and commercialized. The successful design of novel herbicides depends on careful consideration of a number of factors including target enzyme selections and validations, inhibitor designs, and the metabolic fates. Biochemical information can be used to identify enzymes which produce lethal phenotypes. The identification of a lethal target site is an important step to this approach. An examination of the characteristics of known targets provides of crucial insight as to the definition of a lethal target. Recently, antisense RNA suppression of an enzyme translation has been used to determine the genes required for toxicity and offers a strategy for identifying lethal target sites. After the identification of a lethal target, detailed knowledge such as the enzyme kinetics and the protein structure may be used to design potent inhibitors. Various types of inhibitors may be designed for a given enzyme. Strategies for the selection of new enzyme targets giving the desired physiological response upon partial inhibition include identification of chemical leads, lethal mutants and the use of antisense technology. Enzyme inhibitors having agrochemical utility can be categorized into six major groups: ground-state analogues, group specific reagents, affinity labels, suicide substrates, reaction intermediate analogues, and extraneous site inhibitors. In this review, examples of each category, and their advantages and disadvantages, will be discussed. The target identification and construction of a potent inhibitor, in itself, may not lead to develop an effective herbicide. The desired in vivo activity, uptake and translocation, and metabolism of the inhibitor should be studied in detail to assess the full potential of the target. Strategies for delivery of the compound to the target enzyme and avoidance of premature detoxification may include a proherbicidal approach, especially when inhibitors are highly charged or when selective detoxification or activation can be exploited. Utilization of differences in detoxification or activation between weeds and crops may lead to enhance selectivity. Without a full appreciation of each of these facets of herbicide design, the chances for success with the target or enzyme-driven approach are reduced.

• Journal of radiological science and technology
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• v.31 no.4
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• pp.355-365
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• 2008

Purpose : This study isto determine the grade of brain tumor and compare the characteristics in each grade using in MRS (MR Spectroscopy). Method : STEAM (Stimulated Echo Acquisition Method) and protocol of PRESS (Point Resolved Spectroscopy) were used in the levels of tumor grade. We classified the pattern of tumor and analysis of the spectrum signals quantitatively from voxel in the brain tumor grade. In accordance with the result, we calculated the accuracy of biochemical. Result : In high-grade tumor, the NAA/Cr showed the signal reduction of 29.4% and 53.9%. However Cho/Cr increased 570% and 711%. However, in low-grade tumor, NAA/Cr downed to 42.6% and 58.1%. Cho/Cr increased to 188% and 195%. Conclusion : The study suggests that the comparative analysis of signals from MR spectroscopy could be useful to evaluate the grade of tumor and find out the characteristics of it. By extension, MR spectroscopy can be used for research with other organs in the human.

• The Journal of the Korea Contents Association
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• v.9 no.4
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• pp.275-285
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• 2009

During an 8 month period from January to August 2007, complete blood count (CBC) samples were taken from various wards and from the outpatient department at Samsung Medical Center. In order to determine whether or not the total white blood cells were over counted, results were obtained from both the 4Diff/channel and the white blood cell channel from the automated blood analysis equipment from S company for comparison. Among patients who were on long term treatments, the number of cases determined to be over counted by comparing the WBC counts during this 8 month period was 25. Clinical chemistry tests were also conducted on the same day on the 25 samples taken. 68% of the patients showed to exceed normal range of aspartate transaminase (AST) and alanine aminotransferase (ALT) indicating abnormal liver function, and the total bilirubin range were also in excess in 60% of the total samples taken. Further clinical information which was obtained from the patients showed 98% of the patients were administered with cefepime which is the 4th generation cephalosporin at the time when the WEC were over counted. It is assumed that a multiple of factors investigated caused the over count of the WEC rather than a single factor.

• Applied Microscopy
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• v.41 no.4
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• pp.229-234
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• 2011

The occurrence of nuclear inclusions has been reported in various plant groups from primitive ferns to higher flowering plants. Their presence within a group seems to be randomly distributed without any phylogenetic relationships among species. According to the current survey, nuclear inclusions have been widely documented in more than several hundreds of species from various families of plants. The morphology and internal structures of nuclear inclusions are diverse and at least five types of inclusions develop within plant nuclei; amorphous, crystalline, fibrous, lamellar, and tubular form. Among these types, crystalline inclusions are the ones that are the most frequently reported. The inclusions are not bound by membranes and appear to be related to the nucleoli, either spatially by a close association or by an inverse relationship in size during development. The idea that nuclear inclusions are of a proteinaceous nature has been widely accepted. Further link to nucleolar activity as a protein storing site has also been suggested based on the association between the nucleolus and nuclear inclusions. Various investigations of nuclear inclusions have revealed more information about their structural features, but characterizing their precise function and subunit complexity employing molecular analysis and 3-D reconstruction remains to be elucidated. Tilting and tomography of serial sections with appropriate image processing can provide valuable information on their subunit(s). The present review summarizes discussion about different nuclear inclusions in plants from previous works, giving special attention to their fine, ultrastructural morphology, function, and origin.

• Childhood Kidney Diseases
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• v.8 no.2
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• pp.195-204
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• 2004

Purpose: Hypophosphatemic rickets is a hereditary disease, characterized by hypophosphatemia due to renal phosphate wasting, impaired renal production of 1,25-dihydroxyvitamin $D_3$, rachitic bone deformities and impaired growth. The purpose of this study is to provide clinical profiles of patients with hypophosphatemic rickets in our hospital. Methods: Between July 1983 and February 2004, 56 patients were diagnosed as having hypophosphatemic rickets. The medical records of these patients were reviewed retrospectively. Clinical manifestations, family histories, laboratory data, treatment outcomes were described. Results: Fifty six patients were enrolled in this study. The average age at symptom onset and diagnosis were 20 months and 5 years respectively. Fourteen patients had family histories. The main clinical manifestations were bow legs and short stature. There was a significant negative correlation between the ages and the height z-scores at the time of diagnosis(r=-0.47, P=0.005). Initial laboratory data showed normocalcemia, hypophosphatemia, elevated serum alkaline phosphatase, decreased tubular reabsorption of phosphate and a normal range of 1,25-dihydroxyvitamin $D_3$ Radiographic examinations of bone revealed fraying, widening and cupping of the metaphyseal ends. Treatment consisted of Joulie solution and vitamin D metabolites, and resulted in improved biochemical and radiographic findings. However, height z-scores remained essentially unchanged(P=0.224). Complications of treatment were frequently observed, including hyperparathyroidism, nephrocalcinosis, and hypercalciuria. Sixteen patients had corrective osteotomy and 4 of them underwent leg lengthening together. Conclusion: There was a gap of several years between the onset of symptoms and the diagnosis. Early treatment seems to be essential to growth. For the earlier treatment, the offsprings of affected parents should be followed up closely.

• Korean Journal of Plant Resources
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• v.8 no.3
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• pp.325-334
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• 1995

The early senescence mutant induced from Gihobyeo by $\gamma-ray$ irradiation was determined. The mutated gene expression was identified with comparing the characteristic of original cultivar. The mutant had so similar the morphological characteristics to original cultivar that it couldn't be distinguished until senescence occurred at about 20 days after heading. Suddenly yellow leaves were observed within a few days due to great decreases in total chlorophyll and various carotenoid contents. Transmission electron microscopy showed the formation of starch granules, distortion of fine structure of leaf cell organelles, especially grana structures, and the decrease in grain filled after senescence occurred. But banding patterns of total proteins and isozymes have not show any differences, The early senescence mutant will be very useful for study material not only on physiological and biochemical properties of plant senescence but also on gene expression regulating senescence which gives great influence on yield potential and its stability.

• Korean Journal of Microbiology
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• v.50 no.2
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• pp.95-100
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• 2014

Hrq1 is a novel member of RecQ helicase family, found in fungal genomes by bioinformatics analyses. It is most homologous to human RECQL4 and recent genetic and biochemical studies suggested that it may play roles in the maintenance of genome stability. In this study, we investigated yeast two-hybrid interactions between Hrq1 and the yeast genes homologous to the human genes that are known to interact with RECQL4. Among the 11 genes tested, Rad14, a nucleotide excision repair (NER) factor, was found to interact with Hrq1. In addition, pull-down assay with the purified proteins revealed direct protein-protein interaction between Hrq1 and Rad14. The yeast two-hybrid interaction was enhanced by the DNA damage induced by 4-nitroquinoline-1-oxide, which was dependent on the presence of Rad4, a key NER factor. These results suggest that Hrq1 may function in NER through interaction with Rad14.

• Journal of Life Science
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• v.24 no.8
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• pp.915-926
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• 2014

The ribosome is a protein synthesizing machinery and a ribonucleoprotein complex that consists of three ribosomal RNAs (23S, 16S and 5S) and 54 ribosomal proteins in bacteria. In the course of ribosome assembly, ribosomal proteins (r-protein) and rRNAs are modified, the r-proteins bind to rRNAs to form ribonucleoprotein complexes which are folded into mature ribosomal subunits. In this process, a number of non-ribosomal trans-acting factors organize the assembly process of the components. Those factors include GTP- and ATP-binding proteins, rRNA and r-protein modification enzymes, chaperones, and RNA helicases. During ribosome biogenesis, they participate in the modifications of ribosomal proteins and RNAs, and the assemblies of ribosomal proteins with rRNAs. Ribosomes can be assembled from a discrete set of components in vitro, and it is notable that in vivo ribosome assembly is much faster than in vitro ribosome assembly. This suggests that non-ribosomal ribosome assembly factors help to overcome several kinetic traps in ribosome biogenesis process. In spite of accumulation of genetic, structural, and biochemical data, not only the entire procedure of bacterial ribosome synthesis but also most of roles of ribosome assembly factors remain elusive. Here, we review ribosome assembly factors involved in the ribosome maturation of Escherichia coli, and summarize the contributions of several ribosome assembly factors which associate with 50S and 30S ribosomal subunits, respectively.

• Korean Chemical Engineering Research
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• v.60 no.3
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• pp.398-406
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• 2022

The outer membrane of Gram-negative bacteria is the outermost layer of cellular environment in which numerous biophysical and biochemical processes are in action sustaining viability. Advances in cell engineering enable modification of bacterial genetic information that subsequently alters membrane physiology to adapt bacteria to specific purposes. Surface display of a functional molecule on the outer membranes is one of strategies that directs host cells to respond to a specific extracellular matter or stimulus. While intracellular expression of a functional peptide or protein fused to a membrane-anchoring motif is commonly practiced for surface display, the method is not readily applicable to exogenous or large proteins inexpressible in bacteria. Chemical conjugation at reactive groups naturally occurring on the membrane might be an alternative, but often compromises fitness due to non-specific modification of essential components. Herein, we demonstrated two distinct approaches that enable site-specific decoration of the outer membrane with a fluorescent agent in Escherichia coli. An unnatural amino acid genetically incorporated in a surface-exposed peptide could act as a chemoselective handle for bioorthogonal dye labeling. A surface-displayed α-helical domain originating from a part of a selected heterodimeric coiled-coil complex could recruit and anchor a green fluorescent protein tagged with a complementary α-helical domain to the membrane surface in a site- and hetero-specific manner. These methods hold a promise as on-demand tools to confer new functionalities on the bacterial membranes.