• Bulletin of the Korean Chemical Society
• /
• v.30 no.12
• /
• pp.2863-2864
• /
• 2009

• Proceedings of the Zoological Society Korea Conference
• /
• 1999.10b
• /
• pp.278.2-278
• /
• 1999

No Abstract, See Full Text

• Journal of Microbiology and Biotechnology
• /
• v.26 no.1
• /
• pp.20-27
• /
• 2016

Lactobacillus kefiranofaciens ZW3 was obtained from kefir grains, which have high lactose hydrolytic activity. In this study, a heterodimeric LacLM-type β-galactosidase gene (lacLM) from ZW3 was isolated, which was composed of two overlapping genes, lacL (1,884 bp) and lacM (960 bp) encoding large and small subunits with calculated molecular masses of 73,620 and 35,682 Da, respectively. LacLM, LacL, and LacM were expressed in Escherichia coli BL21(DE3) and these recombinant proteins were purified and characterized. The results showed that, compared with the recombinant holoenzyme, the recombinant large subunit exhibits obviously lower thermostability and hydrolytic activity. Moreover, the optimal temperature and pH of the holoenzyme and large subunit are 60℃ and 7.0, and 50℃ and 8.0, respectively. However, the recombinant small subunit alone has no activity. Interestingly, the activity and thermostability of the large subunit were greatly improved after mixing it with the recombinant small subunit. Therefore, the results suggest that the small subunit might play an important role in maintaining the stability of the structure of the catalytic center located in the large subunit.

• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.46 no.4
• /
• pp.76-84
• /
• 2014

Preventive conservation is one of most important issues in the field of conservation for paper-records. Many researchers have been studied environmental factors such as effects of humidity, temperature, biological attack and air pollutants. Air pollutants strongly associated with oxidative and hydrolytic degradation of cellulose. It is important to control air pollutants in storage environment to improve stabilities of conservation environment. Four paper samples have been analyzed for their accelerated aging characteristics by air pollutants, sulfur dioxide, nitrogen dioxide, ozone, carbon monoxide. Physical and optical properties and weight molar masses(Mw) showed that interactions between air pollutants and paper sample. Nitrogen dioxide, ozone caused severe damage to cellulose in paper by hydrolytic and oxidative decompositions during aging.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.4 no.1
• /
• pp.188-197
• /
• 2001

Organophosphorus acid anhydrolases(OPAA) catalyzing the hydrolysis of toxic organophosphates have been found in a variety of prokaryotic and eukaryotic organisms. Of the several kinds of OPAA that can degrade nerve agents, such as DFP, sarin and soman, a OPAA gene harbored in the chromosomal DNA of Alteromonas haloplanktis strain was subcloned in order to develope an enzymatic degradation method of toxic organophosphorus compounds. For this 1481 bp DNA fragment containing OPAA gene and its flanking regions has been synthesized through PCR using chromosomal DNA of A. haloplanktis strain. After subcloning and subsequent expression, crude OPA anhydrolase was prepared and assayed. It was shown that the OPAA had a very high hydrolytic activity on DFP. The specific activity of the enzyme was 1,110 $\mu$mole.$min^{p-1}.mg^{-1}$ protein. It seemed that OPAA with such a high hydrolytic activity may give a good prospects to its use, as a biodegradation tool, in detoxifying toxic organophosphorus compounds, such as pesticides and chemical stockpiles which are posing a potential threat to the field environment and human health.

• Journal of Microbiology and Biotechnology
• /
• v.16 no.8
• /
• pp.1306-1310
• /
• 2006

Sphingomonas sp. strain SB5 could degrade carbofuran and carbofuran-7-phenol to a hydrolytic product, 2-hydroxy-3-(3-methlypropan-2-o1)phenol, and several red metabolites. However, the chemical structures of the red metabolites have largely remained unidentified. In this study, we identified the structure of one of the red metabolites as 5-(2-hydroxy-2-methyl-propyl)-2,2-dimethyl- 2,3-dihydro-naphtho[2,3-6]furan-4,6,7,9-tetrone by using mass spectrometric and NMR ($^1$H, $^{13}$C) analyses. It is suggested that the red metabolite resulted from condensation of some metabolites in the degradation of 2-hydroxy-3-(3-methlypropan-2-o1)phenol, a hydrolytic product derived from carbofuran. To our knowledge, this is the first paper to report a red metabolite in bacterial degradation of the insecticide carbofuran.

• Korean Journal of Materials Research
• /
• v.15 no.3
• /
• pp.172-176
• /
• 2005

Formation of aluminum hydroxide by a hydrolytic reaction of nano aluminum powder synthesized by a pulsed wire evaporation (PWE) method has been studied. The type and morphology of the hydroxides were investigated with various initial temperatures and pHs. The nano fibrous boehmite (AlOOH) was formed predominantly over $40^{\circ}C$ of the hydrolytic temperature in acid solution, while the bayerite $(Al(OH)_3)$ was formed predominantly below $30^{\circ}C$ in alkali solution with a faceted crystalline structure. As a result the boehmite showed a much larger specific surface area (SSA) than that of bayerite. The highest SSA of the boehmite was about $409\;m^2/g$.

• Macromolecular Research
• /
• v.10 no.2
• /
• pp.85-90
• /
• 2002

Poly (ethylene oxide)/polylatide/poly(ethylene oxide) (PEO/PL/PEO) tri-block copolymers, which each block is connected by ester bond, were synthesized by coupling reaction of PL with PEO in the presence of pyridine. PL/PEO/PL tri-block copolymer was synthesized by ring opening polymerization of L-lactide initiated by PEO in the presence of stannous octoate. Degradation behavior of the copolymers was investigated in a pH 7.4 phosphate buffer saline (PBS) at 37$\pm$1 $^{\circ}C$. Gel permeation chromatography (GPC) and $^1$H-nuclear magnetic resonance (NMR) were used to monitor the change of mass loss, molecular weight and composition of copolymers. In hydrolytic degradation, the PEO/PL/PEO tri-block copolymer with high PEO contents affected the increase of its mass loss, and resulted in the decrease of its molecular weight as well as PEO composition. However, when PL/PEO/PL and PEO/PL/PEO tri-block copolymers had similar PEO contents, PEO/PL/PEO decreased faster in molecular weight and PEO composition than PL/PEO/PL.

• Bulletin of the Korean Chemical Society
• /
• v.32 no.2
• /
• pp.477-482
• /
• 2011

The structural analysis of polytrimethylene terephthalate (PTT) and characterization of the hydrolytic degradation products after acid hydrolysis were performed using MALDI-TOF mass spectrometry. Mass spectra of the PTT samples were analyzed using a self-calibration method as well as an internal calibration method with standard materials of known masses. PTT structures constituting the samples were determined from the analyses of the spectra, and their relative compositions were estimated. The MALDI-TOF mass spectra of the acid-hydrolyzed PTT sample showed three main series of oligomer products with different end groups in accordance with the hydrolysis schemes. From the spectra of both $Na^+$ and $K^+$ adducts, it was concluded that the PTT samples have higher affinity for $Na^+$ compared with $K^+$ and therefore show higher ionization efficiency with sodium ions when dithranol is used as a matrix. Two different wavelength laser beams ($\lambda$ = 337 nm and 355 nm) were tested and it was observed that the 355 nm beam was more efficient in obtaining the MALDI spectra of PTT using dithranol as a matrix under our experimental conditions.

• Korean journal of applied entomology
• /
• v.17 no.3 s.36
• /
• pp.139-142
• /
• 1978

Activities of several hydrolytic enzymes in the rusted pear loaves were estimated. Tested enzymes were cellulase (Cx), invertase $\beta-amylase$, pectinase (pectinmethylesterase and polygalacturonase), and phosphatase. Enzyme activities represented by pH value-enzyme activitycurve. Activities of Cx. invertase. and $\beta-amylase$ were higher in the healthy part than those in the near-lesion and lesion parts. and showed the maximal activities around pH 7.0. On the other hand, activities of pectinase and phosphatase were higher in the lesion and near-lesion parts than in the healthy part. Pectinmethylesterase activities in the healthy and diseased parts were different with different curve-pattern as the pH of treating solution changed.