Analyzing public preferences and increasing acceptability for the Renewable Portfolio Standard in Korea

Shin, J.,Woo, J.,Huh, S.Y.,Lee, J.,Jeong, G. IPC Science and Technology Press ; Elsevier Scienc 2014 ENERGY ECONOMICS Vol.42 No.-

In order to respond to the challenge of climate change, similar to other countries, Korea has announced various policies to vitalize the development and uptake of renewable energy. The Renewable Portfolio Standard (RPS) is the most striking example of a policy in this area. This study employs a conjoint survey and Bayesian mixed logit model to analyze consumer preferences for specific attributes of the RPS policy. It analyzes households' marginal willingness to pay (MWTP) for the RPS with specific attributes and simulates the degree of household acceptability of the policy through a scenario analysis. Comparison between costs and benefits of implementing the policy is also attempted by analyzing the households' MWTP with the actual transition expense of RPS implementation incurred by electricity supply companies. The simulation results provide implications for improving RPS policy implementation; households consider the creation of new jobs as the most important policy attribute, followed by increase in electricity prices, damage to forests, reduction in CO<SUB>2</SUB> emissions, and length of power outages. Moreover, the Korean household is willing to accept an increase of up to 1.39% in its electricity prices (relative to 2012), and the median MWTP of each household for RPS implementation is KRW 734.99/month (USD 0.67/month).

Automatic protein structure prediction system enabling rapid and accurate model building for enzyme screening

Seo, J.H.,Lee, G.S.,Kim, J.,Cho, B.K.,Joo, K.,Lee, J.,Kim, B.G. IPC Science and Technology Press ; Elsevier Scienc 2009 Enzyme and microbial technology Vol.45 No.3

Protein structure prediction has great potential of understanding the function of proteins at the molecular level and designing novel protein functions. Here, we report rapid and accurate structure prediction system running in an automated manner. Since fold recognition of the target protein to be modeled is the starting point of the template-guided model building process, various approaches - such as profile analysis, threading, and SCOP fold classification - have been applied to generate the template library and to select the best template structure. After the best template was determined, fold consistency within the template candidates was considered using TM-score and SCOP database to select additional template structures among the template library. To generate a total of 100 decoy sets, MODELLER was used with the selected template structure. The predicted decoys were clustered with the RMSD deviation criterion of 3A to obtain centroids from each cluster. Finally, the selected centroids were subject to side-chain rearrangement using SCWRL module. Our fully automated structure prediction system was examined with sample test sets consisting of recently released 80 PDB chains. Judged by the TM-score (>=0.4), we concluded that 60 cases (75%) showed similar structures of statistical significance. This prediction system provides the users with simple and reliable models within hours of query submission, so that it is quite simply used for high throughput enzyme screening.

Forecasting volatility of crude oil markets

Kang, S.H.,Kang, S.M.,Yoon, S.M. IPC Science and Technology Press ; Elsevier Scienc 2009 ENERGY ECONOMICS Vol.31 No.1

This article investigates the efficacy of a volatility model for three crude oil markets - Brent, Dubai, and West Texas Intermediate (WTI) - with regard to its ability to forecast and identify volatility stylized facts, in particular volatility persistence or long memory. In this context, we assess persistence in the volatility of the three crude oil prices using conditional volatility models. The CGARCH and FIGARCH models are better equipped to capture persistence than are the GARCH and IGARCH models. The CGARCH and FIGARCH models also provide superior performance in out-of-sample volatility forecasts. We conclude that the CGARCH and FIGARCH models are useful for modeling and forecasting persistence in the volatility of crude oil prices.

Synthesis of thermo- and acid-stable novel oligosaccharides by using dextransucrase with high concentration of sucrose

Seo, E.S.,Nam, S.H.,Kang, H.K.,Cho, J.Y.,Lee, H.S.,Ryu, H.W.,Kim, D. IPC Science and Technology Press ; Elsevier Scienc 2007 Enzyme and microbial technology Vol.40 No.5

A method is presented for synthesizing thermo-, acid-stable oligosaccharides (TASO) from sucrose (2.5-4M) using a dextransucrase prepared from Leuconostoc mesenteroides B-512FMCM. The degree of polymerization (DP) of oligosaccharides synthesized was from 2 to 11. TASO resisted hydrolysis of its glycosidic linkages at 140<SUP>o</SUP>C and pH 6.0 for 1h. It was stable at pH's ranging from 2 to 4 at 120<SUP>o</SUP>C. These oligosaccharides effectively inhibited the formation of insoluble glucan, the growth and acid production of Streptococcus sobrinus. However, it stimulated the growth of probiotic organisms such as Bifidobaterium sp. TASO potentially can be used as sweeteners for the food and beverages where thermo- and acid-stable properties are required and as potential inhibitors of dental caries.

Microbial transformation of the bioactive sesquiterpene, cyclonerodiol, by the ascomycete Penicillium sp. and the actinomycete Streptomyces sp.

Li, X.,Kim, Y.H.,Jung, J.H.,Kang, J.S.,Kim, D.K.,Choi, H.D.,Son, B.W. IPC Science and Technology Press ; Elsevier Scienc 2007 Enzyme and microbial technology Vol.40 No.5

Biological transformation of the bioactive sesquiterpene, cyclonerodiol (1), isolated from marine-derived fungus Myrothecium sp., was studied. Preparative-scale fermentation of 1 with marine-derived fungus Penicillium sp. resulted in the isolation of a new glycosidic metabolite, 7-O-(β-d-mannopyranosyl)cyclonerodiol (2). Fermentation of 1 for 2 weeks with a marine isolate of the actinomycete bacteria Streptomyces sp. also afforded two oxidized geometrical isomers, 10(Z)- and 10(E)-cyclonerotriols (3, 4). The stereostructure of the metabolites obtained was assigned on the basis of detailed spectroscopic data analyses and chemical reaction.

Construction of a fusion enzyme of dextransucrase and dextranase: Application for one-step synthesis of isomalto-oligosaccharides

Kim, Y.M.,Seo, M.Y.,Kang, H.K.,Atsuo, K.,Kim, D. IPC Science and Technology Press ; Elsevier Scienc 2009 Enzyme and microbial technology Vol.44 No.3

The linear isomalto-oligosaccharides (IMO) with DP2-DP10 were produced by one-step process using engineered fusion enzyme (DXSR) of endo-dextranase and only α-(1-6) glucan synthesizing dextransucrase. The fusion enzyme was successfully expressed in Escherichia coli and characterized. Compared to individual enzymes, DXSR had 150% increased endo-dextranase activity and 98% decreased dextransucrase activity. The partially purified DXSR displayed molecular mass of 240kDa as analyzed by SDS-PAGE. It showed both enzyme activities on analysis by zymogram. The thermal- and pH-stability of DXSR was around 28<SUP>o</SUP>C and pH at 5.0-6.4, respectively. IMOs production by DXSR was increased by the addition of metal ions such as Fe<SUP>2+</SUP>, Li<SUP>+</SUP>, K<SUP>+</SUP> and Ni<SUP>2+</SUP>, but the enzyme was strongly inhibited by Hg<SUP>2+</SUP> and Ag<SUP>+</SUP>. DXSR produced linear IMO with DP2-DP10 using sucrose as a sole substrate. The molecular weight and amount of IMO could be controlled by the sucrose concentration. DXSR gave 30-fold higher production of IMO than that of an equal activity mixture of the two enzymes such as dextranase and dextransucrase.

Synthesis and characterization of hydroquinone glucoside using Leuconostoc mesenteroides dextransucrase

Seo, E.S.,Kang, J.,Lee, J.H.,Kim, G.E.,Kim, G.J.,Kim, D. IPC Science and Technology Press ; Elsevier Scienc 2009 Enzyme and microbial technology Vol.45 No.5

We synthesized a hydroquinone glucoside (HG) as a potential skin-whitening agent using Leuconostoc mesenteroides (B-1299CB BF563) dextransucrase with hydroquinone (HQ) as an acceptor and sucrose as a donor. The product was purified using butanol partitioning and silica gel column chromatography. The structure of the purified HG was determined by nuclear magnetic resonance and the ionic product was observed at m/z 295 (C12, H16, O7 Na)<SUP>+</SUP>. HG was identified as 4-hydroxyphenyl-α-d-glucopyranoside. The optimum condition of HG synthesis, determined using a response surface methodology, was 450mM HQ, 215mM sucrose, and 0.55U/mL dextransucrase; the final HG produced was 544mg/L. The IC<SUB>50</SUB> of diphenylpicryl-hydrazyl scavenging activity was 3.85mM indicating a higher antioxidant activity compared to β-arbutin (IC<SUB>50</SUB>=6.04mM). HG-mediated inhibition of lipid peroxidation was 3.51% that of HQ (100%) and much higher than that of β-arbutin (0.81% of HQ). In addition the IC<SUB>50</SUB> value of nitrite-scavenging activity was 14.76mM showing a superior scavenging activity to that of β-arbutin (IC<SUB>50</SUB>=27.09mM).

Synthesis, structural analysis and application of novel acarbose-fructoside using levansucrase

Nam, S.H.,Moon, Y.H.,Kang, J.,Kim, Y.M.,Robyt, J.F.,Kim, D. IPC Science and Technology Press ; Elsevier Scienc 2009 Enzyme and microbial technology Vol.45 No.4

Acarbose-fructoside (acarbose-Fru) was newly synthesized via the acceptor reaction of a levansucrase from Leuconostoc mesenteroides B-512 FMC with acarbose and sucrose. The resultant product was separated with 10.5% purification yield via Bio-gel P-2 column chromatography and HPLC. Its structure was determined to be 1<SUP>I</SUP>-β-d-fructofuranosyl α-acarbose, according to the results of <SUP>1</SUP>H, <SUP>13</SUP>C, HSQC, and HMBC analyses. Acarbose-Fru was inhibited competitively on α-glucosidase (A. niger and baker's yeast) but mixed noncompetitively on α-amylases (A. oryzae and porcine pancreatic). Compared to acarbose, acarbose-Fru exhibited inhibition potency of 1.12 or 1.52 on A. niger α-glucosidase or A. oryzae α-amylase, respectively. Additionally, acarbose-Fru was identified as a novel substrate for dextransucrase with K<SUB>m</SUB> and V<SUB>max</SUB> values of 189.0mM and 8.51μmol/(mgmin), respectively. Therefore, acarbose-Fru as a substrate might be synthesized novel acarbose derivatives by using dextransucrase.

Characteristics of cold-adaptive endochitinase from Antarctic bacterium Sanguibacter antarcticus KOPRI 21702

Park, H.J.,Kim, D.,Kim, I.H.,Lee, C.E.,Kim, I.C.,Kim, J.Y.,Kim, S.J.,Lee, H.K.,Yim, J.H. IPC Science and Technology Press ; Elsevier Scienc 2009 Enzyme and microbial technology Vol.45 No.5

The psychrotrophic Sanguibacter antarcticus KOPRI 21702<SUP>T</SUP>, isolated from Antarctic seawater, produced a cold-adapted chitinolytic enzyme that is a new 55kDa family 18 chitinase (Chi21702). Chi21702 exhibited high activities toward pNP-(GlcNAc)<SUB>2</SUB> and pNP-(GlcNAc)<SUB>3</SUB> with no activity for pNP-GlcNAc, indicating that it prefers chitin chains longer than dimers, just as endochitinases do. A mixture of GlcNAc and GlcNAc<SUB>2</SUB> was produced as a main product by Chi21702 activity from chitin oligosaccharides and swollen chitin, while less GlcNAc<SUB>3</SUB> was produced. These results show that Chi21702 has an endochitinase activity, randomly hydrolyzing chitin at internal sites. Chi21702 displayed chitinase activity at 0-40<SUP>o</SUP>C (optimal temperature of 37<SUP>o</SUP>C), maintained its activity at pH 4-11 (optimal pH of 7.6). Interestingly, Chi21702 exhibited relative activities of 40% and 60% at 0 and 10<SUP>o</SUP>C, respectively, in comparison to 100% at 37<SUP>o</SUP>C, which is higher than those of the previously characterized, cold-adapted, chitinases from bacterial strains.

Development of thermostable lipase B from Candida antarctica (CalB) through in silico design employing B-factor and RosettaDesign

Kim, H.S.,Le, Q.A.T.,Kim, Y.H. IPC Science and Technology Press ; Elsevier Scienc 2010 Enzyme and microbial technology Vol.47 No.1

Organic synthesis reactions demand improved characteristics of enzymes than wild type such as reactivity, thermostability, enantioselectivity and so on. Especially thermostability of enzyme is highly important since reaction at higher temperature has many advantages such as elevated reaction rate and increased solubility of substrates. Due to this requirement, a rational approach was employed to develop thermostable CalB. The first step of this approach was the selection of appropriate sites showing a high 'B-factor' value. These sites were chosen on the basis of atomic displacement parameters obtained from X-ray data. These selected sites were then substituted with other amino acids that were determined to be more rigid than the original amino acids by computational modeling using 'RosettaDesign'. As a result of this rational approach, several thermostable CalB mutants including R249L were produced. The residual activity of R249L CalB was two times higher than that of wild type CalB at 55<SUP>o</SUP>. Melting temperature (T<SUB>m</SUB> of R249L mutant increased to 56.8<SUP>o</SUP> compared with wild type CalB (T<SUB>m</SUB> 54.5<SUP>o</SUP>), which was determined by DSF (differential scanning fluorimetry). Additionally, packing analysis tool ''Voronoia'' pointed out that one cavity close to residue 249 of wild type CalB disappeared in CalB R249L, which could be the reason for the increase in thermal stability of CalB R249L mutant compared wild type CalB.