Young-Kyoon Kim

Bakerol: An unusual nor-acorane hemiketal from Cupressus bakeri foliage

Abstract Foliage of Cupressus bakeri was found to contain several acorane-related sesquiterpenoids. One of these was bakerol, a new nor-acorane hemiketal with a 3,5,5,8-tetramethyldicyclopenta[b,c]furan carbon skeleton; about 3% of the keto tautomer 2,6-dimethyl-9-(1-hydroxy-1-methylethyl)-spiro[4.4]nonan-1-one) was observed. Bakerol is also present in a related cypress, C. nevadensis.

Alkene isomerizations with boron trichloride-hydrogen chloride solutions

Abstract The combination of boron trichloride and hydrogen chloride in dichloromethane at 0°C catalyzes facile alkene isomerizations in certain steroid systems which are not affected by HCl in the absence of BCl 3 .

Effect of Nanocellulose and Aminated Starch on Tensile and Thermal Properties of Plasticized Starch Film

This study investigated the effect of nanocellulose, such as microfibrillated cellulose (MFC) and cellulose nanocrystal (CNC), and aminated starch on tensile property and thermal stability of plasticized starch film. Glycerol (23 wt%) was used as a plasticizer and nanocelluloses of 1-30 parts per hundred parts of resin (phr) in the basis of plasticized starch were added. Tensile strength and elastic modulus increased with increasing nanocellulose addition amount, whereas elongation at break decreased. Tensile properties of MFC-reinforced starch film were higher than those of CNC-reinforced film. Optimum addition amount of aminated starch, which is commonly used for paper sizing, to improve tensile property of film, was found to be 5%. And 1% addition of aminated starch showed the best effect in the improvement of tensile property of the film. Thermal stability was improved with the addition of MFC to plasticized starch film with and without aminated starch.

Phylogenetic analysis of Reticulitermes speratus using the mitochondrial cytochrome C oxidase subunit I gene.

ABSTRACT Reticulitermes speratusis commonly found in Asia, including Korea and Japan. We recently analyzed the 5 region of mitochondrial cytochrome c oxidase subunit I to perform a phylogenetic analysis of R. speratus KMT1, isolated in Seoul, Korea. Our results, using COXI, suggest that the taxonomy of R. sper-atus should be reconsidered with regard to the subgenus group. A similar phylogenetic analysis by COXI and COXII demonstrated the reliability of COXI genetic information in a molecular phylogenetic analysis of termites. Keywords : Reticulitermes speratus, Cytochrome c oxidase subunit I, phylogeny, taxonomy 1. INTRODUCTION The termite is an economically significant insect in the wood industry. New Orleans, USA, spends over US

Cellulose Hydrolysis by Digestive Enzymes of Reticulitermes speratus, a Native Termite from Korea

300 million annually for damages of wooden structures that are caused mostly by Coptotermes formosanus (Alan and Weste, 2003). Korean traditional wooden houses in Seoul, Korea also had a termite damage which might be accel-erated by modern temperature control facilities (Son and Lee, 2008). It is expected that in Korea, the termite damage on wooden structures will be expanded and intensified in consequence of global warming. In East Asia, more than 70 species of Reticulitermes have been reported, and 5 species of Reticulitermes have been identified in Japan (Take- matsu, 1999). R. speratus is the termite specie found in South Korea (Lee et al., 2001; Ra et al., 2005; Son and Lee, 2008) and has been suggested to have migrated from China through southern Japan (Park et al., 2006).Morphological observations have been used to classify termites (Takematsu, 1999; Kitade and Hayashi, 2002; Koshikawa et al., 2004). New ge-netic approaches have been adopted in the last dec-ade and have modified and strengthened older ter-mite taxonomy. Termite, the order Isoptera, is con-sisted with 7 families. The family Rhinotermitidae has extremely heterogeneous genera with 17 genus and 350 species (Lee and Ryu, 2003). Analysis of the mitochondrial cytochrome c oxidase subunit II (COXII) gene showed that the family Rhinotermi-

Immobilization of cellulases from Fomitopsis pinicola and their changes of enzymatic characteristics.

This study was to investigate the enzymatic hydrolysis of cellulose using the cellulase from whole body of the native termite collected in Milyang-si, Kyungsangnamdo, Korea. In the results, optimal temperature and pH for the enzyme of native termites were and pH 5.5 for both endo--1, 4-glucanase and -glucosidase. Enzyme activity of the termite enzyme was shown . And the highest glucose hydrolysis rate of cellulose by the digestive enzyme from test termites was 24.5% based on the glucan, comparing 59.7% by commercial enzyme (only celluclast 1.5 L) at 1% (w/v) substrate and 36 hours in hydrolysis time. This hydrolysis rate by the digestive enzyme from test termites was comparatively high value in 41% level of the commercial enzyme. When cellulose was hydrolyzed by the digestive enzyme of the native termite, glucose hydrolysis was almost completed in 12 hours which was the considerably reduced time for cellulose hydrolysis. It was suggested that the quiet short reaction time for cellulose hydrolysis by the enzyme from native termite could be a very high advantage for development of hydrolysis cellulase for lignocellulosic biomass.

Analysis of Cytotoxic Constituent of Berberis koreana Palibin

Cellulase from Formiptosis pinicola KMJ812 is an efficient cellulose degradation enzyme complex, especially with a high -glucosidase activity. In this study, the change in enzymatic characteristics by immobilization and the reduction of immobilized enzyme activity by repeated usages were evaluated using cellulases from F. pinicola KMJ812. Among tested four resins, Duolite A568 resin had the best enzyme activity yield with 61.7% cellulase activity and 64.4% - glucosidase activity during the cellulase immobilization. The best reaction temperature was for both cellulase and -glucosidase activities which were higher than the unimmobilized soluble cellulases. The best reaction pH was 4.0 for cellulase activity which was a little more basic than a soluble form and 4.5 for -glucosidase activity. The immobilized cellulase activity was remained 98% of the beginning activity after 72 h incubation at and 50% of the beginning activity after eight times usage at .