• BMB Reports
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• 제44권2호
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• pp.102-106
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• 2011

Thermodynamic stability and refolding kinetics of firefly luciferase and three representative mutants with depletion of negative charge on a flexible loop via substitution of Glu by Arg (ER mutant) or Lys (EK mutant) as well as insertion of another Arg in ER mutants (ERR mutant) was investigated. According to thermodynamic studies, structural stability of ERR and ER mutants are enhanced compared to WT protein, whereas, these mutants become prone to aggregation at higher temperatures. Accordingly, it was concluded that enhanced structural stability of mutants depends on more compactness of folded state, whereas aggregation at higher temperatures in mutants is due to weakening of intermolecular repulsive electrostatic interactions and increase of intermolecular hydrophobic interactions. Kinetic results indicate that early events of protein folding are accelerated in mutants.

• 한국해양바이오학회지
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• 제6권2호
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• pp.47-52
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• 2014

Oxidation stability and cold fuid property are considered as the most important factors for determining biodiesel quality. Among the fatty acids, monounsaturated fatty acid satisfy both oxidation stability and cold flow property of biodiesel quality standards. Microalgae with high monounsaturated fatty acid contents is have some benefit for producing to produce biodiesels with satisfying quality standards. In this study, monounsaturated fatty acid contents of a isolated microalga from Youngheung island was analyzed. Phaeodactylum tricornutum was isolated by streaking, and growth rate and fatty acid composition of the algae were investigated. Total FAME contents were consisted of 26% of saturated fatty acids, 43% of monounsaturated fatty acids, and 18% of polyunsaturated fatty acids. The contents of monounsaturated fatty acid were especially high in the Phaeodactylum species. This result implies that the FAMEs from P. tricornutum may contribute to improve the oxidation stability and cold flow property of biodiesel.

• 한국발생생물학회지:발생과생식
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• 제25권4호
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• pp.313-319
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• 2021

Hub cells comprise a niche for germline stem cells and cyst stem cells in the Drosophila testis. Hub cells arise from common somatic gonadal precursors in embryos, but the mechanism of their specification is still poorly understood. Here we find that RNA binding proteins Lin28 and Imp mediate transcript stability of Bowl, a known hub specification factor; Bowl transcripts were reduced in the testis of Lin28 and Imp mutants, and also when RNA-mediated interference against Lin28 or Imp was expressed in hub cells. In tissue culture Luciferase assays involving the Bowl 3'UTR, stability of Luc reporter transcripts depended on the Bowl 3'UTR and required Lin28 and Imp. Our findings suggest that proper Bowl function during hub cell specification requires Lin28 and Imp in the testis hub cells.

• BMB Reports
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• 제42권12호
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• pp.829-833
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• 2009

Angiogenin is a member of the ribonuclease superfamily that induces the formation of new blood vessels. It has been suggested that the surface loop of angiogenin defined by residues 59-71 plays a special role in angiogenic function (1); however, the mechanism of action is not clearly defined. To elucidate the role of the surface loop on the structure, function and stability of angiogenin, three surface loop mutants were produced in which 14 amino acids in the surface loop of RNase A were substituted for the 13 amino acids in the corresponding loop of angiogenin. The structure, stability and biological functions of the mutants were then investigated using biophysical and biological approaches. Even though the substitutions did not influence the overall structure of angiogenin, they affected the stability and angiogenic function of angiogenin, indicating that the surface loop of angiogenin plays a significant role in maintaining the stability and angiogenic function of angiogenin.

• Korea-Australia Rheology Journal
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• 제17권2호
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• pp.63-69
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• 2005

The stability of low-speed spinning process exhibiting spinline flow-induced crystallization (FIC) with no neck-like spinline deformation has been investigated using the method of linear stability analysis. Effects of various process conditions such as fluid viscoelasticity and the spinline cooling on the spinning stability have been found closely related to the development of the spinline crystallinity. It also has been found that the FIC makes the system less stable or more unstable than no FIC cases when the spinline crystallinity reaches its maximum possible value, whereas the FIC generally stabilizes the system if the crystallinity doesn't reach its maximum value on the spinline. It is believed that the destabilizing effect of the FIC on low-speed spinning when the crystallinity is fully developed on the spinline is due to the reduction of the real spinning length available for deformation on the spinline. On the other hand, the increased spinline tension caused by the FIC when the maximum crystallinity is not reached on the spinline and thus no reduction in the spinning length occurs, makes the sensitivity of spinline variables to external disturbances smaller and hence stabilizes the system. These linear stability results are consistent with the findings by nonlinear transient simulation, as first reported by Lee et al. (2005b).

• Biotechnology and Bioprocess Engineering:BBE
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• 제11권3호
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• pp.258-261
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• 2006

The addition of zeolite particles enhances the stability of mRNA molecules in a cell-free protein synthesis system. When $20{\mu}g/{\mu}L$ of zeolite (Y5.4) is added to a reaction mixture of cell-free protein synthesis, a substantial increase in protein synthesis is observed. The stabilizing effect of zeolite is most dearly observed in an in vitro translation reaction directed by purified mRNA, as opposed to a coupled transcription and translation reaction. Upon the addition of zeolite in the in vitro translation reaction, the life span of the mRNA molecules is substantially extended, leading to an 80% increase in protein synthesis. The effect of zeolite upon the mRNA stability appears be strongly related to the cation exchange (potassium to sodium) reaction. Our results demonstrate the possibility of modifying this biological process using heterogeneous, non-biological substances in a cell-free protein synthesis system.

• Journal of Applied Biological Chemistry
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• 제66권
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• pp.512-518
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• 2023

To address inherent weaknesses such as low mechanical strength and limited enzyme loading capacity in conventional chitosan or alginate beads, an additional step involving the exchange of anionic surfactants with hydroxide ions was employed to prepare porous chitosan hydrogel capsules for enzyme immobilization. Consequently, excellent thermal stability and long-term storage stability were confirmed. Furthermore, coating the porous chitosan hydrogel capsules with polydopamine not only improved mechanical stability but also exhibited remarkable enzyme immobilization efficiency (97.6% for M1-D0.5). Additionally, it was demonstrated that the scope of application for chitosan hydrogel beads, prepared using conventional methods, could be further expanded by introducing an additional step of polydopamine coating. The enzyme immobilization matrix developed in this study can be selectively applied to suit specific purposes and is expected to be utilized as a support for the adsorption or covalent binding of various substances.

• Journal of Electrical Engineering and Technology
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• 제8권6호
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• pp.1530-1541
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• 2013

The coexistence and extinction of species are important concepts for biological systems and can be distinguished by an investigation of stability. When determining local stability of nonlinear systems, Lyapunov indirect method based on the Jacobian linearization has been widely employed due to its simplicity. Despite such popularity, it is not applicable to singular systems whose Jacobian has at least one eigenvalue that is equal to zero. In such singular cases, an appropriate Lyapunov function should be sought to determine the stability of systems, which is rather difficult and quite involved. In this paper, we seek for a simple criterion to determine stability of the equilibrium that is located at the boundary of the positive orthant, when one of eigenvalues of the Jacobian is zero. The goal of the paper is to present a generalized condition for the equilibrium to attract all trajectories that starting from initial condition in the positive orthant and near the equilibrium. Unlike the Lyapunov direct method, the proposed method requires just a simple algebraic computation for checking the stability of the critical point. Our approach is applied to various biological systems to show the effectiveness of the proposed method.

• 한국고분자학회:학술대회논문집
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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• pp.246-246
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• 2006

Ionic polymer-metal composite (IPMC) soaked with various ionic liquids was prepared by using polystyrene sulfonic acid-grafted poly(vinylidene fluoride-co-hexafluoropropylene) as ion-exchange membrane (IEM). The prepared IPMCs were effectively deformed three times larger and actuated for 300 times longer than those of Nafion with water at the same applied conditions. The experimental results indicated than the increase in the bending capability can be caused by the increase in the improved properties of the IEMs and ionic liquids such as uptake content and ionic conductivity. And air-operating stability of the IPMCs is appreciably governed by various physical and electrochemical properties of soaked solvents in IEMs.

• 한국동물학회:학술대회논문집
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• 한국동물학회 2001년도 한국생물과학협회 학술발표대회
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• pp.209.3-209
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• 2001

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