• Journal of Microbiology and Biotechnology
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• v.27 no.5
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• pp.1023-1031
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• 2017

The conformational change of cellular prion protein ($PrP^C$) to its misfolded counterpart, termed $PrP^{Sc}$, is mediated by a hypothesized cellular cofactor. This cofactor is believed to interact directly with certain amino acid residues of $PrP^C$. When these are mutated into cationic amino acid residues, $PrP^{Sc}$ formation and prion replication halt in a dominant negative (DN) manner, presumably due to strong binding of the cofactor to mutated $PrP^C$, designated as DN PrP mutants. Previous studies demonstrated that plasminogen and its kringle domains bind to PrP and accelerate $PrP^{Sc}$ generation. In this study, in vitro binding analysis of kringle domains of plasminogen to Q167R DN mutant PrP (PrPQ167R) was performed in parallel with the wild type (WT) and Q218K DN mutant PrP (PrPQ218K). The binding affinity of PrPQ167R was higher than that of WT PrP, but lower than that of PrPQ218K. Scatchard analysis further indicated that, like PrPQ218K and WT PrP, PrPQ167R interaction with plasminogen occurred at multiple sites, suggesting cooperativity in this interaction. Competitive binding analysis using $\small{L}$-lysine or $\small{L}$-arginine confirmed the increase of the specificity and binding affinity of the interaction as PrP acquired DN mutations. Circular dichroism spectroscopy demonstrated that the recombinant PrPs used in this study retained the ${\alpha}$-helix-rich structure. The ${\alpha}$-helix unfolding study revealed similar conformational stability for WT and DN-mutated PrPs. This study provides an additional piece of biochemical evidence concerning the interaction of plasminogen with DN mutant PrPs.

• BMB Reports
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• v.31 no.6
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• pp.590-594
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• 1998

X-ray crystallographic studies of the deoxy form of human adult hemoglobin (Hb A) have shown that ${\beta}99Asp$ is hydrogen bonded to both ${\alpha}42Tyr$ and ${\alpha}97Asn$ in the ${\alpha}_1{\beta}_2$ subunit interface, suggesting that the essential role of ${\beta}99Asp$ is to stabilize the deoxy-Hb by creating the intersubunit hydrogen bond. In particular, for Hb Kempsey (${\beta}99Asp{\rightarrow}Asn$), molecular dynamics simulation indicated that a new hydrogen bond involving ${\beta}99Asn$ can be induced by replacing ${\alpha}42Tyr$ with a strong hydrogen-bond acceptor such as Asp. Designed mutant recombinant (r) Hb (${\beta}99Asp{\rightarrow}Asn$, ${\alpha}42Tyr{\rightarrow}Asp$) have been produced in the Escherichia coli expression system and have shown that functional defects of Hb Kempsey could be compensated by the ${\alpha}42Tyr{\rightarrow}Asp$ substitution. However, as the ${\alpha}42 Tyr{\rightarrow}Asp$ mutation has never been reported before, it is still possible that the functional properties of r Hb (${\beta}99Asp{\rightarrow}Asn$, ${\alpha}42Tyr{\rightarrow}Asp$) may be due to the mutation itself. Thus, it is required to produce r Hb (${\alpha}42Tyr{\rightarrow}Asp$) and r Hb Kempsey (${\beta}99Asp{\rightarrow}AsnX$( as controls, and to compare their properties with those of r Hb (${\beta}99Asp{\rightarrow}Asn$, ${\alpha}42Tyr{\rightarrow}Asp$). r Hb (${\alpha}42Tyr{\rightarrow}Asp$) could not be purified because it is an unstable hemoglobin which forms Heinz bodies. r Hb Kempsey (${\beta}99Asp{\rightarrow}Asn$) exhibits very high oxygen affinity and greatly reduced cooperativity. Thus, r Hb (${\beta}99Asp{\rightarrow}Asn$) and r Hb (${\alpha}42Tyr{\rightarrow}Asp)$ compensate each other.

• Journal of Gifted/Talented Education
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• v.20 no.2
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• pp.487-502
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• 2010

The purpose of this study was to examine the effect of SSC(Small-Scale Chemistry) lab program applying to scientifically gifted students' classes. The participants were 15 the middle school scientifically gifted students selected and enrolled in science-gifted education center of university. SSC lab program was applied for 3 month with 5 topics. The research design was one group pretest-posttest design, the data were analyzed using the PASW 18 statistics program. The results of this study were as follows: First, the scientific attitude of scientifically gifted students was improved significantly(p<.01) after applying SSC lab program. Especially, there were significant difference between pre-test and post-test in the scores of cooperativity, spontaneity, perseverance, which were the sub-region of scientific attitude. Second, the creative personality characteristics of scientifically gifted students showed statistically significant improvements(p<.01) after applying SSC lab program. Especially, there was significant difference between pre-test and post-test in the scores of adhesion, which was a sub-region of the creative personality characteristics. Third, there were no significant differences in the science inquiry skills between before and after applying the SSC lab program in the scientifically gifted students' classes(p>.05). The results suggest that SSC Lab program is an effective program in scientifically gifted students' classes.

• The Korean Journal of Physiology
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• v.20 no.2
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• pp.257-270
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• 1986

It has been reported that the luteal function may be regulated by the intracellular calcium in luteal cells (Higuchi et al, 1976; Dorflinger et at, 1984; Gore and Behrman, 1984) which is adjusted partially by $Ca^{++}-ATPase$ activities in luteal cell membranes (Verma and Pennistion, 1981). However, the physicochemical and kinetic properties of $Ca^{++}-ATPase$ in luteal membranes were not fully characterized. This study was, therefore, undertaken to partially characterize the physicochemical and kinetic properties of $Ca^{++}-ATPase$ system in luteal membranes and microsomal fractions, known as an one of the major $Ca^{++}$ storge sites (Moore and Pastan, 1978), from the highly luteinized ovary Highly luteinized ovaries were obtained from PMSG-hCG injected immautre female rats. Light membrane and heavy membrane fractions and microsomal fractions were prepared by the differential and discontinuous sucrose density gradient centrifugation method desribed by Bramley and Ryan (1980). Light membrane and heavy membrane fractions and microsomal fractions from highly luteinized ovaries are composed of the two different kinds of $Ca^{++}-ATPase$ system. One is the high affinity $Ca^{++}-ATPase$ which is activated in low $Ca^{++}$ concentration (Km, 10-30 nM), the other is low affinity $Ca^{++}-ATPase$ activated in higher $Ca^{++}$ concentration $(K_{1/2},\;40\;{\mu}M)$. At certain $Ca^{++}$ concentrations, activities of high and low affinity $Ca^{++}-ATPase$ are the highest in light membrane fractions and are the lowest in microsomal fractions. It appeares that high affinity $Ca^{++}-ATPase$ system have 2 binding sites for ATP (Hill's coefficient; around 2 in all membrane fractions measured) and the positive cooperativity of ATP bindings obviously existed in each membrane fractions. The optimum pH for high affinity $Ca^{++}-ATPase$ activation is around S in all membrane fractions measured. The lipid phase transition temperature measured by Arrhenius plots of high affinity $Ca^{++}-ATPase$ activity is around $25^{\circ}C$. The activation energies of high affinity $Ca^{++}-ATPase$ below the transition temperature are similar in each membrane fractions, but at the above transition temperature, it is the hightest in heavy membrane fractions and the lowest in microsomal fractions. According to the above results, it is suggested that intracellular $Ca^{++}$ level, which may regulate the luteal function, may be adjusted primarily by the high affinity $Ca^{++}-ATPase$ system activated in intracellular $Ca^{++}$ concentration range $(below\;0.1\;{\mu}M)$.

• Journal of the Korean Chemical Society
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• v.26 no.2
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• pp.65-72
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• 1982

STO-3G level computations were performed on n-propylamine, n-propylamine radical and cis-and trans-ethylene diamines in order to investigate structural contributions of (n${\pi}$/m) and (n-${\sigma}^*$) structures to the energy variations accompanying the conformational changes. It was found that (5${\pi}$/5) and (4${\pi}$/4) structures had attractive and repulsive nonbonded interactions, respectively, which were approximately additive. anti(n-${\sigma}^*$) structures had more stabilzing hyperconjugative interactions than syn(n-${\sigma}^*$) structures, but due to the large internuclear repulsion the net effect was destabilizing inthe former in contrast with the net stabilizing contribution in the latter. Moreover it was found that the stabilizing ${\pi}$-nonbond structure, (5${\pi}$/5) was always cooperatively reinforced by the more stabilizing anti(n-${\sigma}^*$) interaction, whereas the destabilizing (4${\pi}$/4) structure was accompanied by the less stabilizing syn(n-${\sigma}^*$) interaction. This type of cooperativity was found general through-bond interaction of the terminal lone pair lobes split the energy levels into two, $n_+ = \frac{1}{\sqrt{2}}(n_1 + n_2)$ and $n_- = \frac{1}{\sqrt{2}}(n_1 - n_2)$, the latter being the lower level, which can be shown using simple overlap patterns of the two lobes with a common vicinal ${\sigma}^*$ orbital.

• Journal of Science Education
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• v.40 no.2
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• pp.131-143
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• 2016

This research was conducted to investigate the effects under which learner-generated pictorial representation introduced in summary stage of lesson serve as an instructional strategy improving academic achievement and scientific attitude. The subjects of this study were 152 students (experimental group: 38 boys and 39 girls, control group: 36 boys and 39 girls). Using the learner-generated pictorial representation were applied to experimental group, whereas summarizing the lesson in writing to control group. The results of this study were as follows: First, there was no significant difference between the two groups in the post achievement results. But, a statistically significant difference on a delayed post-test of academic achievement was found between experimental and control groups. Second, there was no significant difference between boys and girls in the post achievement test. But a significantly positive effects on the academic achievement was found in boys of experimental group. Third, experimental group scored higher than the control group in all sub-domains of the scientific attitude; curiosity, openness, criticism, cooperativity, willingness, perseverance. Findings suggest the descriptive drawing is a viable way for elementary students to understand scientific concepts and to improve scientific attitude.