• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.17 no.2
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• pp.43-46
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• 2011

Effect of several PLA films on strawberry packaging was investigated. Three types of PLA film (non-perforated PLA1, perforated films of PLA2 and PLA3) were used for packing strawberry and the fruit quality was measured during 6 day storage at 10. For comparison, two types of OPP/PE film (non-perforated OPP1 and perforated OPP2) were used for strawberry packaging. Weight loss of all the treatments was below 0.12% after 6 day, seeming to be in tolerable range. PLA3 package showed the best retention in fruit firmness, PLA2 and PLA3 packages the least changes in acidity, and PLA2 package gave the least changes of soluble solid content and vitamin C content. There have been no differences in surface color among packages. Perforated PLA films could be effective for use as packaging of strawberry.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.17 no.1
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• pp.1-5
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• 2011

Soybean sprouts of 100 g were packed with commercial OPP/PE films and developed PLA films, and stored at $10^{\circ}C$ for 6 days. Effects of packaging film were investigated. The weight loss of OPP/PE film was higher than that of the PLA film. Total cell count of PLA2 and PLA3 packages was the lowest among 5 packages. Off-flavor was strong at OPP/PE, but that in PLA2 was very little. Vitamin C content of PLA2 was highest and preference test of PLA2 was also highest among 5 packages. Finally, the PLA packages for soybean sprouts was more suitable than OPP/PE.

• YAKHAK HOEJI
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• v.45 no.4
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• pp.407-412
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• 2001

A $Ca^{2+}$_dependent PLA$_2$activity termed rPLA$_2$, was detected in the cytosol of bovine red blood cells (RBCs). The rPLA$_2$was characterized as a similar form to Group IV cPLA$_2$, but different in several column chromatographic profiles including an anion exchange column. To examine whether this rPLA$_2$is different from the well characterized cPLA$_2$, a quinone derivative, BJ50, was developed and tested for the inhibitory effect on the two PLA$_2$enzymes. The rPLA$_2$activity was inhibited by a quinone derivative (BJ50) with ID$_{50}$ of 20 $\mu$M., but had no effect on the cPLA$_2$, suggesting that rPLA$_2$may be a novel type of cytosolic PLA$_2$in RBCs.s.s.

• Polymer(Korea)
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• v.37 no.2
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• pp.249-253
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• 2013

From poly(lactic acid) (PLA) and poly(propylene carbonate) (PPC) synthesized using $CO_2$, a PLA/PPC/PLA layered film is prepared by coextrusion and then stretched to uniaxial orientation. The mechanical, optical, and barrier properties and shrinkage of the prepared film were investigated in detail. The maximum shrinkage of PLA/PPC/PLA film reached to 60% at $75^{\circ}C$. With increasing PPC content, the ratio of shrinkage of the film was increased and its shrinkagerate was increased. The ratio of shrinkage of the film decreased with increasing stretching temperature. The prepared film has oxygen and vapor transmission barrier properties. In this study, the PLA/PPC/PLA film is expected to be commercialized as a environmentally friendly shrinkable film.

• Journal of Microbiology and Biotechnology
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• v.30 no.8
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• pp.1244-1251
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• 2020

Phospholipase A₂ (PLA₂) from Streptomyces violaceoruber is a lipolytic enzyme used in a wide range of industrial applications including production of lysolecithins and enzymatic degumming of edible oils. We have therefore investigated expression and secretion of PLA₂ in two workhorse microbes, Pichia pastoris and Escherichia coli. The PLA₂ was produced to an activity of 0.517 ± 0.012 U/ml in the culture broth of the recombinant P. pastoris. On the other hand, recombinant E. coli BL21 star (DE3), overexpressing the authentic PLA₂ (P-PLA₂), showed activity of 17.0 ± 1.3 U/ml in the intracellular fraction and 21.7 ± 0.7 U/ml in the culture broth. The extracellular PLA2 activity obtained with the recombinant E. coli system was 3.2-fold higher than the corresponding value reached in a previous study, which employed recombinant E. coli BL21 (DE3) overexpressing codon-optimized PLA₂. Finally, we observed that the extracellular PLA₂ from the recombinant E. coli P-PLA₂ culture was able to hydrolyze 31.1 g/l of crude soybean lecithin, an industrial substrate, to a conversion yield of approximately 95%. The newly developed E. coli-based PLA₂ expression system led to extracellular production of PLA₂ to a productivity of 678 U/l·h, corresponding to 157-fold higher than that obtained with the P. pastoris-based system. This study will contribute to the extracellular production of a catalytically active PLA₂.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.17 no.1
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• pp.7-11
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• 2011

This research was conducted to compare the quality of paprika ($Capsicum$ $annuum$ L.) packed with PLA film and OPP/PE film pouches during storage at $6^{\circ}C$. Weight loss of paprika fruit was higher in OPP/PE film pouches, mold decay was shown in OPP/PE pouches after 6 days, but was not yet shown in PLA pouches. Hardness decreased in all packages. Soluble solid content was highest in PLA1 film pouch, vitamin C content was also highest in PLA2. Mold decay was not shown in PLA pouches after 9 day, but shown at calyx of paprika fruit in OPP/PE pouches. Off-flavor was strong in the OPP/PE pouches when the pouches were opened, decay was also serious in the same pouches after 15 days and thus quality was inadequate for sale in market.

• Korean journal of applied entomology
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• v.53 no.3
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• pp.271-280
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• 2014

Some bacterial metabolites of Xenorhabdus nematophila (Xn) inhibit phospholipase $A_2$ ($PLA_2$) activity to shutdown eicosanoid biosynthesis in target insects. However, little has been known about the target insect $PLA_2$ of these bacterial metabolites. Eight bacterial metabolites identified in Xn culture broth exhibited significant insecticidal activities against larvae of both lepidopteran species of Plutella xylostella and Spodoptera exigua. Moreover, these bacterial metabolites significantly enhanced insecticidal activities of Bacillus thuringiensis (Bt). To determine target $PLA_2$, we cloned and over-expressed cellular $PLA_2$ ($SecPLA_2$) of S. exigua. Purified $SecPLA_2$ catalyzed phospholipids derived from the fat body and released several polyunsaturated fatty acids. Most Xn metabolites significantly inhibited $SecPLA_2$ activity, but were different in their inhibitory activities. There was a positive correlation between the inhibition of $SecPLA_2$ and the enhancement of Bt insecticidal activity. These results indicate that $SecPLA_2$ is a molecular target inhibited by Xn metabolite.

• Journal of Photoscience
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• v.2 no.1
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• pp.1-5
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• 1995

The activity of phospholipase A$_2$ (PLA$_2$) was identified and characterized from cytosolic and membrane fractions of oat cells, respectively. PLA$_2$ activity was determined fluorometrically in the presence of serum albumin using phospholipids labeled at sn-2-acyl position with 10-pyrenyldecanoic acid. When the cell-free extracts of oat tissues were fractionated by ultracentrifugation at 100,000 x g and the PLA$_2$ activity was assayed, we found that most of the PLA$_2$ activity was revealed from the cytoplasmic fraction rather than from the membrane fraction. The activity of cytosolic PLA$_2$ was dependent on Ca$^{2+}$ concentration and the optimum concentration of Ca$^{2+}$ was found to be 100 $\mu$M. It was also found that PLA$_2$ could be translocated toward the membrane site from the cytosol upon increasing Ca$^{2+}$ concentration. These results might suggest that an increased [Ca$^{2+}$]$_i$ by phytochrome action could promote the translocation of the cytosolic PLA$_2$ toward the membrane site.

• The Korean Journal of Physiology and Pharmacology
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• v.14 no.3
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• pp.163-167
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• 2010

This study investigated the effects of the methanol extracts of Morinda citrifolia containing numerous anthraquinone and iridoid on phospholipase $A_2$ ($PLA_2$) isozyme. $PLA_2$ activity was measured using various $PLA_2$ substrates, including 10-pyrene phosphatidylcholine, 1-palmitoyl-2-[$^{14}C$]arachidonyl phosphatidylcholine ([$^{14}C$]AA-PC), and [$^3H$]arachidonic acid (AA). The methanol extracts suppressed melittin-induced [$_3H$]AA release in a concentration-dependent manner in RAW 264.7 cells, and inhibited $cPLA_2/sPLA_2$-induced hydrolysis of [$^{14}C$]AA-PC in a concentration- and time-dependent manner. A Dixon plot showed that the inhibition by methanol extracts on $cPLA_2$ and $sPLA_2$ appeared to be competitive with inhibition constants ($K_i$) of $3.7{\mu}g/ml$ and $12.6{\mu}g/ml$, respectively. These data suggest that methanol extracts of Morinda citrifolia inhibits both $Ca^{2+}$-dependent $PLA_2$ such as, $cPLA_2$ and $sPLA_2$. Therefore, Morinda citrifolia may possess anti-inflammatory activity secondary to $Ca^{2+}$-dependent $PLA_2$ inhibition.

• Korean Journal of Pharmacognosy
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• v.40 no.1
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• pp.13-17
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• 2009

It was previously reported that yeast elicitor transiently increased oleanolic acid and ursolic acid in Scutellaria baicalensis suspension cultures and also doubled phospholipase $A_2$ ($PLA_2$) activity. Thus, $PLA_2$ was purified from the soluble fractions of S. baicalensis suspension cultures and the characters of the purified $PLA_2$ were identified. The $PLA_2$ was purified about 160 times compared with the starting soluble-protein extract from S. baicalensis suspension culture cells. The purified protein showed a molecular mass of about 43 kDa by SDS-PAGE. The purified plant $PLA_2$ had a neutral pH optimum (pH 7.0) and required $Ca^{2+}$ for activity. The $PLA_2$ activity was inhibited by mammalian $PLA_2$ inhibitors such as 5,8,11,14-eicosatetraynoic acid(ETYA) and arachidonyl trifluoromethyl ketone ($AACOCF_3$).