• Journal of Photoscience
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• v.7 no.1
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• pp.35-37
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• 2000

Photolysis of $\alpha$-(o-alkylphenyl) indanones resulted in $\alpha$-cleavage followed by disproportionation to form E-and Z- ortho-formyl stilbenes. No evidences of hydrogen abstraction reactions were collected from these indanones. The minimum rate constant of $\alpha$-cleavage in the $\alpha$-(o-alkylphenyl) indanones was estimated to be 5.5$\times$10$^{10}$ s$^{-1}$ .

• Journal of Animal Science and Technology
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• v.57 no.8
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• pp.27.1-27.6
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• 2015

This study was designed to investigate the effects of ${\alpha}$-tocopherol and granulosa cells monolayer on nuclear maturation and cleavage rates of ovine cumulus-oocyte complexes (COCs). The COCs (n = 2814) were matured in maturation medium supplemented with various concentration of ${\alpha}$-tocopherol (0, 5, 10, $15{\mu}g/ml$), oocytes were incubated at $39^{\circ}C$ with 5 % $CO_2$ for 24 h in three culture systems: (a) maturation medium (MM; n = 884), (b) co-cultured with granulosa cells (CG; n = 982) and (c) co-cultured with granulosa cells and cells were further cultured in MM for 12 h (CG + 12hMM; n = 948). Our results showed that ${\alpha}$-tocopherol had no effect on GVBD and MII as compared to control group, but when ${\alpha}$-tocopherol added to maturation medium the rate of cleavage decreased. This indicates interaction of above mentioned factors in any of the treatments showed no significant differences on the rate of maturation and cleavage stages (MII, GVBD and cleavage) (p > 0.05). The oocytes co-cultured with granulosa cells for 24 h had beneficial effects on cleavage rate. The maximum MII and cleavage rates were achieved when oocytes had extra 12 h culture in the maturation medium without granulosa cells. Results also showed our modified co-culture system (CG + 12hMM), improved rates of MII and the cleavage in comparison with other studied maturation systems.

• Journal of Photoscience
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• v.12 no.2
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• pp.83-85
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• 2005

Photochemical reactivities of ${\beta}-ethoxypropiophenones$ are changed dramatically by putting a halogen at a position to the carbonyl functionality. ${\alpha}-Bromo-{\beta}-ethoxypropiophenone$ gives C-Br bond cleavage products solely, but ${\alpha}-chloro-{\beta}-ethoxypropiophenone$ forms mainly the Yang photocyclization products upon irradiation. The different reactivities of two compounds can be explained by relative rates of C-X bond cleavage and a-hydrogen abstraction.

• BMB Reports
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• v.33 no.5
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• pp.379-384
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• 2000

The native conformation of serpins (serine protease inhibitors) is strained. Upon cleavage of the reactive center loop of serpins by a protease, the amino terminal portion of the cleaved loop is inserted into the central ${\beta}-sheet$, A sheet, as the fourth strand, with the concomitant release of the native strain. We questioned the role of protease in this conformational switch from the strained native form into a stable relaxed state. Chemical cleavage of the reactive center loop of ${\alpha}_1-antitrypsin$, a prototype serpin, using hydroxylamine dramatically increased the stability of the serpin. A circular dichroism spectrum and peptide binding study suggests that the amino terminal portion of the reactive center loop is inserted into the A sheet in the chemically-cleaved ${\alpha}_1-antitrypsin$, as in the enzymatically-cleaved molecule. These results indicate that the structural transformation of a serpin molecule does not require interaction with a protease. The results suggest that the serpin conformational switch that occurred during the complex formation with a target protease is induced by the cleavage of the reactive center loop per se.

• Applied Microscopy
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• v.34 no.1
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• pp.71-81
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• 2004

When U. unicinctus mature oocytes were fertilized in vitro, germinal vesicle breakdown (GVBD) and meioses occurred and the zygotes entered cleavage stage. A modified pattern of spiral cleavages, suggestively based on behavior of mitotic spindles, have been observed in this work. The first and second cleavages were meridional and the third was equatorial, and then followed by repetitions of meridional-equatorial cleavage. The cleavage of the isolecithal egg were equal and holoblastic and its patterns were spiral. The anti-${\alpha}-,-{\beta}$- tubulin reactions and confocal microscopy revealed mitotic apparates tilted obliquely at each mitosis causing oblique displacements of the blastomeres. Despite isolecithal distribution of yolk, this observations implicated that tilting of mitotic apparates induced spiral cleavage and the displacements of blastomeres. However, these features would not be the typical spiral cleavage, but represented a modified pattern of known Spiralian s in the sense of the equal cleavage. During the first cleavage, heart-shaped eggs have been produced. Electron microscopies exhibited the first cleavage furrow extended with its membranous structure deeply into the cytoplasm. Contractile ring has not been observed.

• Journal of Embryo Transfer
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• v.14 no.1
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• pp.9-15
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• 1999

This study was conducted to investigate the effect of $\alpha$-tocopherol and cysteamine with Whitten's medium in supporting the development on in vitro maturation(IVM), in vitro fertilization (IVF) and in culture(IVC) on porcine oocytes. When the immature oocytes were cultured of $\alpha$-tocopherol for 40h, the nuclear maturation rates were 39, 4, 52.5 and 54.1%, respectivley. The nuclear maturation rates of treat groups were signficantly (P<0.05) higher than those of non-treat groups. After matureation, the oocytes were inseminated in vitro in medium 199 with ejaculated spermatoza for examination of sperm penetration, polyspermy, male pronuclear(MPN) formation, and cleavage rate. Sperm penetration rates of treat higher than the control groups(P<0.05), and MPN formation rates were significantly(P<0.05) higher on treated groups (24.3~53.1%) than control groups(14.2~21.4%). After insemination, the cleavage rates at 120hr were groups higher than control groups(P<0.05).

• Bulletin of the Korean Chemical Society
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• v.25 no.11
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• pp.1623-1624
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• 2004

• Journal of Photoscience
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• v.11 no.32
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• pp.75-76
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• 2004

${\alpha}$,${\alpha}$-Dibromovalerophenone and ${\alpha}$,${\alpha}$-dichlorovalerophenone were prepared and their photochemical behaviors were investigated. The former gives C-Br cleavage products and the latter gives mainly the Yang photocyclization products upon irradiation. The reactivity of the chlorine substituted ketone turned out to be quite different from that of ${\alpha}$,${\alpha}$-difluorovalerophenone which gives both the cyclization and elimination products from the 1,4-biradical intermediate.

• Bulletin of the Korean Chemical Society
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• v.25 no.1
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• pp.42-44
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• 2004

Valerophenones containing a substituent at alpha position to the carbonyl group show the remarkable substituent effects on their photochemical reactions. ${\alpha}$-Bromovalerophenone gives only the C-Br bond cleavage products, but the ${\alpha}$-chlorovalerophenone follows the classical Norrish/Yang reaction pathway predominantly.

• Journal of Korea Foresty Energy
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• v.17 no.1
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• pp.56-70
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• 1998

This study was carried out to investigate the structural characteristics of kraft lignin and the wood degrading characteristics, the productivity of ligninolytic enzymes and the enzymatic degradation of kraft lignin by white-rot fungi. To purify kraft lignin, precipitation of kraft pulping black liquors of pitch pine meal was done by titration with lN $H_{2}SO_{4}$ reaching to pH 2, and isolation of the precipitates done by centrifugation. The isolated precipitates from pitch pine were redissloved in lN NaOH, reprecipitated by titration with lN $H_{2}SO_{4}$, washed with deionized water, and kept ofr analysis after freeze drying. Fractionation of the precipitates in solution by successive extraction with $CH_{2}Cl_{2}$ and MeOH, and the fractionates were named SwKL, SwKL I, SwKL II, and SwKL III for pitch pine kraft lignin. The more molecular weights of kraft lignin increased, the less phenolic hydroxyl groups and the more aliphatic hydroxyl groups. Because as the molecular weights increased, the ratio of etherified guaiayl/syringyl(G/S ratio) and the percentage were increased. The spectra obtained by 13C NMR and FTIR assigned by comparing the chemical shifts of various signals with shifts of signals from autherized ones reported. The optimal growth temperature and pH of white-rot fungi in medium were $28^{\circ}C$ and 4.5-5.0, respectively. Especially, in temperature and pH range, and mycelial growth, the best white-rot fungus selected was Phanerochaete chrysosporium for biodegradation. For the degradation pathways, the ligninolytic fungus jcultivated with stationary culture using medium of 1% kraft lignin as a substrate for 3 weeks at $28^{\circ}C$. The weight loss of pitch pine kraft lignin was 15.8%. The degraded products extracted successively methoanol, 90% dioxane and diethyl ether. The ether solubles were analyzed by HPLC. Kraft lignin degradation was initiated in $\beta$-O-4 bonds of lignin by the laccase from Phanerochaete chrysosporium and the degraded compounds were produced from the cleavage of $C\alpha$-$C\beta$ linkages at the side chains by oxidation process. After $C\alpha$-$C\beta$ cleavage, $C\alpha$-Carbon was oxidized and changed into aldehyde and acidic compounds such as syringic acid, syringic aldehyde and vanilline. And the other compound as quinonemethide, coumarin, was analyzed. The structural characteristics of kraft lignin were composed of guaiacyl group substituted functional OHs, methoxyl, and carbonyl at C-3, -4, and -5 and these groups were combinated with $\alpha$ aryl ether, $\beta$ aryl ether and biphenyl. Kraft lignin degradation pathways by Phanerochaete chrysosporium were initially accomplished cleavage of $C\alpha$-$C\beta$ linkages and $C\alpha$ oxidation at the propyl side chains and finally cleavage of aromatic ring and oxidation of OHs.