Production of d-psicose from d-fructose by whole recombinant cells with high-level expression of d-psicose 3-epimerase from Agrobacterium tumefaciens

Park, C.S.,Park, C.S.,Shin, K.C.,Oh, D.K. Society for Bioscience and Bioengineering, Japan ; 2016 Journal of bioscience and bioengineering Vol.121 No.2

<P>The specific activity of recombinant Escherichia coli cells expressing the double-site variant (133L-S213C) D-psicose 3-epimerase (DPEase) from Agrobacterium tumefaciens was highest at 24 h of cultivation time in Terrific Broth (TB) medium among the media tested. The contents of crude protein and DPEase in recombinant cells at 24 h were 37.0 and 8.6% (w/w), respectively, indicating that the enzyme was highly expressed. The reaction conditions for the production of D-psicose from D-fructose by whole recombinant cells with the highest specific activity were optimal at 60 degrees C, pH 8.5, 4 g/l cells, and 700 g/l D-fructose. Under these conditions, whole recombinant cells produced 230 g/I D-psicose after 40 min, with a conversion yield of 33% (w/w), a volumetric productivity of 345 g/l/h, and a specific productivity of 86.2 g/g/h. These are the highest conversion yield and volumetric and specific productivities of D-psicose from D-fructose by cells reported thus far. (C) 2015, The Society for Biotechnology, Japan. All rights reserved.</P>

Substrate specificity of a recombinant d-lyxose isomerase from Providencia stuartii for monosaccharides

Kwon, H.J.,Yeom, S.J.,Park, C.S.,Oh, D.K. Society for Bioscience and Bioengineering, Japan ; 2010 Journal of bioscience and bioengineering Vol.110 No.1

The specific activity and catalytic efficiency (k<SUB>cat</SUB>/K<SUB>m</SUB>) of the recombinant putative protein from Providencia stuartii was the highest for d-lyxose among the aldose substrates, indicating that it is a d-lyxose isomerase. Gel filtration analysis suggested that the native enzyme is a dimer with a molecular mass of 44 kDa. The maximal activity for d-lyxose isomerization was observed at pH 7.5 and 45 <SUP>o</SUP>C in the presence of 1 mM Mn<SUP>2+</SUP>. The enzyme exhibited high isomerization activity for aldose substrates with the C2 and C3 hydroxyl groups in the left-hand configuration, such as d-lyxose, d-mannose, l-ribose, d-talose, and l-allose (listed in decreasing order of activity). The enzyme exhibited the highest activity for d-xylulose among all pentoses and hexoses. Thus, d-lyxose was produced at 288 g/l from 500 g/l d-xylulose by d-lyxose isomerase at pH 7.5 and 45 <SUP>o</SUP>C for 2 h, with a conversion yield of 58 % and a volumetric productivity of 144 g l<SUP>-1</SUP> h<SUP>-1</SUP>. The observed k<SUB>cat</SUB>/K<SUB>m</SUB> (920 mM<SUP>-1</SUP> s<SUP>-1</SUP>) of P. stuartiid-lyxose isomerase for d-xylulose is higher than any of the k<SUB>cat</SUB>/K<SUB>m</SUB> values previously reported for sugar and sugar phosphate isomerases with monosaccharide substrates. These results suggest that the enzyme will be useful as an industrial producer of d-lyxose.

Selective hydrogenation of d-glucose to d-sorbitol over HY zeolite supported ruthenium nanoparticles catalysts

Mishra, D.K.,Dabbawala, A.A.,Park, J.J.,Jhung, S.H.,Hwang, J.S. Elsevier Science Publishers 2014 CATALYSIS TODAY - Vol.232 No.-

HY zeolite (HYZ) supported ruthenium (Ru) nanoparticles catalyst (Ru/HYZ) is prepared by simple impregnation method and is characterized by using energy dispersive X-ray analysis (EDX), transmission electron microscopy (TEM), CO chemisorption and inductively coupled plasma (ICP) mass spectrometry. The catalyst Ru/HYZ is evaluated in hydrogenation of d-glucose and hydrogenation experiments to produce a selective product d-sorbitol were conducted batch wise in a three-phase laboratory scale reactor. The kinetics studies of d-glucose hydrogenation using the catalyst Ru/HYZ were carried out. In the operating regime studied the rate of reaction showed first orders dependency with respect to d-glucose and hydrogen. For affording maximum d-glucose conversion, yield and selectivity to d-sorbitol, the reaction conditions were also optimized.

Vitamin D deficiency impairs glucose-stimulated insulin secretion and increases insulin resistance by reducing PPAR-γ expression in nonobese Type 2 diabetic rats

Park, S.,Kim, D.S.,Kang, S. Butterworths ; Elsevier Science Ltd 2016 The Journal of nutritional biochemistry Vol.27 No.-

<P>Human studies have provided relatively strong associations of poor vitamin D status with Type 2 diabetes but do not explain the nature of the association. Here, we explored the physiological pathways that may explain how vitamin D status modulates energy, lipid and glucose metabolisms in nonobese Type 2 diabetic rats. Goto-Kakizaki (GK) rats were fed high-fat diets containing 25 (VD-low), 1000 (VD-normal) or 10,000 (VD-high) cholecalciferol-IU/kg diet for 8 weeks. Energy expenditure, insulin resistance, insulin secretory capacity and lipid metabolism were measured. Serum 25-OH-D levels, an index of vitamin D status, increased dose dependently with dietary vitamin D. VD-low resulted in less fat oxidation without a significant difference in energy expenditure and less lean body mass in the abdomen and legs comparison to the VD-normal group. In comparison to VD-low, VD-normal had lower serum triglycerides and intracellular fat accumulation in the liver and skeletal muscles which was associated with down-regulation of the mRNA expressions of sterol regulatory element binding protein-1c and fatty acid synthase and up-regulation of gene expressions of peroxisome proliferator-activated receptors (PPAR)-alpha and carnitine palmitoyltransferase-1. In euglycemic hyperinsulinemic clamp, whole-body and hepatic insulin resistance was exacerbated in the VD-low group but not in the VD-normal group, possibly through decreasing hepatic insulin signaling and PPAR-gamma expression in the adipocytes. In 3T3-L1 adipocytes 1,25-(OH)(2)-D (10 nM) increased triglyceride accumulation by elevating PPAR-gamma expression and treatment with a PPAR-gamma antagonist blocked the triglyceride deposition induced by 1,25-(OH)2-D treatment. VD-low impaired glucose-stimulated insulin secretion in hyperglycemic clamp and decreased beta-cell mass by decreasing beta-cell proliferation. In conclusion, vitamin D deficiency resulted in the dysregulation of glucose metabolism in GK rats by simultaneously increasing insulin resistance by decreasing adipose PPAR-gamma expression and deteriorating beta-cell function and mass. (C) 2015 Elsevier Inc. All rights reserved.</P>

Cyclobuxine D의 토끼 적출 장관에 대한 작용

이종화,박영현,조병헌,김종배,김정목,김유재,김천숙,차영덕,김영석 최신의학사 1988 最新醫學 Vol.31 No.1

Exendin-4 induction of cyclin D1 expression in INS-1 beta-cells: involvement of cAMP-responsive element.

Kim, M-J,Kang, J-H,Park, Y G,Ryu, G R,Ko, S H,Jeong, I-K,Koh, K-H,Rhie, D-J,Yoon, S H,Hahn, S J,Kim, M-S,Jo, Y-H Journal of Endocrinology, Ltd. [etc.] 2006 The Journal of endocrinology Vol.188 No.3

<P>Glucagon-like peptide-1 (GLP-1) and its analog exendin-4 (EX) have been considered as a growth factor implicated in pancreatic islet mass increase and beta-cell proliferation. This study aimed to investigate the effect of EX on cyclin D1 expression, a key regulator of the cell cycle, in the pancreatic beta-cell line INS-1. We demonstrated that EX significantly increased cyclin D1 mRNA and subsequently its protein levels. Although EX induced phosphorylation of Raf-1 and extracellular-signal-regulated kinase (ERK), both PD98059 and exogenous ERK1 had no effect on the cyclin D1 induction by EX. Instead, the cAMP-elevating agent forskolin induced cyclin D1 expression remarkably and this response was inhibited by pretreatment with H-89, a protein kinase A (PKA) inhibitor. Promoter analyses revealed that the cAMP-responsive element (CRE) site (at position -48; 5'-TAACGTCA-3') of cyclin D1 gene was required for both basal and EX-induced activation of the cyclin D1 promoter, which was confirmed by site-directed mutagenesis study. For EX to activate the cyclin D1 promoter effectively, CRE-binding protein (CREB) should be phosphorylated and bound to the putative CRE site, according to the results of electrophoretic mobility shift and chromatin immunoprecipitation assays. Lastly, a transfection assay employing constitutively active or dominant-negative CREB expression plasmids clearly demonstrated that CREB was largely involved in both basal and EX-induced cyclin D1 promoter activities. Taken together, EX-induced cyclin D1 expression is largely dependent on the cAMP/PKA signaling pathway, and EX increases the level of phosphorylated CREB and more potently trans-activates cyclin D1 gene through binding of the CREB to the putative CRE site, implicating a potential mechanism underlying beta-cell proliferation by EX.</P>

Protein Profile in Corpus Luteum during Pregnancy in Korean Native Cows

Chung, H.J.,Kim, K.W.,Han, D.W.,Lee, H.C.,Yang, B.C.,Chung, H.K.,Shim, M.R.,Choi, M.S.,Jo, E.B.,Jo, Y.M.,Oh, M.Y.,Jo, S.J.,Hong, S.K.,Park, J.K.,Chang, W.K. Asian Australasian Association of Animal Productio 2012 Animal Bioscience Vol.25 No.11

Steroidogenesis requires coordination of the anabolic and catabolic pathways of lipid metabolism, but the profile of proteins associated with progesterone synthesis in cyclic and pregnant corpus luteum (CL) is not well-known in cattle. In Experiment 1, plasma progesterone level was monitored in cyclic cows (n = 5) and pregnant cows (n = 6; until d-90). A significant decline in the plasma progesterone level occurred at d-19 of cyclic cows. Progesterone level in abbatoir-derived luteal tissues was also determined at d 1 to 5, 6 to 13 and 14 to 20 of cyclic cows, and d-60 and -90 of pregnant cows (n = 5 each). Progesterone level in d-60 CL was not different from those in d 6 to 13 CL and d-90 CL, although the difference between d 6 to 13 and d-90 was significant. In Experiment 2, protein expression pattern in CL at d-90 (n = 4) was compared with that in CL of cyclic cows at d 6 to 13 (n = 5). Significant changes in the level of protein expression were detected in 32 protein spots by two-dimensional polyacrylamide gel electrophoresis (2-DE), and 23 of them were identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). Six proteins were found only in pregnant CL, while the other 17 proteins were found only in cyclic CL. Among the above 6 proteins, vimentin which is involved in the regulation of post-implantation development was included. Thus, the protein expression pattern in CL was disorientated from cyclic luteal phase to mid pregnancy, and alterations in specific CL protein expression may contribute to the maintenance of pregnancy in Korean native cows.

D상 유화물을 이용한 W/O 유화물의 제조와 특성

남기대,김형진,정노희,윤영균,박관선 한국유화학회 1998 한국응용과학기술학회지 Vol.15 No.2

The emulsion stability of W/O emulsion prepared by D phase emulsification during storage and handling is studied by using phase diagrams. The process of D phase emulsification begins with the formation of isotropic surfactant solution, followed by formation of oil-in-surfactant (O/D) gel emulsion by dispersion of octamethylcyclotetrasiloxane(OMCS) in the surfactant solution. Polyols were essential components for this purpose. To understand the function of polyols, the solution behavior of nonionic surfactant/oil/water/polyol systems were investigated by the ternary phase diagrams of polyoxyethylene loeyl ether/OMCS/propylene glycol(PG) aqueous solutions. The addition of PG increased the solubility of oil in the isotropic surfactant phase. D phase emulsification method has been applied to a new type of cosmetics. By using this emulsification technique, O/W emulsion were formed without a need for adjust of HLB. Fine and stable W/O emulsions were prepared by D phase emulsion.

The effect of encapsulant discoloration and delamination on the electrical characteristics of photovoltaic module

Park, N.C.,Jeong, J.S.,Kang, B.J.,Kim, D.H. Pergamon Press 2013 Microelectronics and reliability Vol.53 No.9

Discoloration and delamination (D&D) of encapsulant in a photovoltaic (PV) module affect the electrical characteristics. Therefore, in this study D&D-induced degradations are investigated with a 25-year-old PV module. The average power output of 25-year-old PV modules decreased by 17.9% compared to initial value. However, insulation properties have been stable over 25years. Electroluminescence image shows that discoloration has an effect on the cell degradation. The effect of D&D on the light reflectance and transmittance is evaluated by performing a trapezoidal integration with the standard global reference spectrum. Failure analysis reveals that delamination occurs at the interface between encapsulant and solar cell and also shows that corrosion of solder occurred near delamination site

Fabrication and characterization of 3D-printed bone-like β-tricalcium phosphate/polycaprolactone scaffolds for dental tissue engineering

Park, >,.,Lee, S.J.,Jo, H.H.,Lee, J.H.,Kim, W.D.,Lee, J.Y.,-→Park, S.A. Korean Society of Industrial and Engineering Chemi 2017 Journal of industrial and engineering chemistry Vol.46 No.-

<P>beta-tricalcium phosphate (beta-TCP) and polycaprolactone (PCL) composites were manufactured using the lab-made 3D bioprinting system to produce 50TCP50PCL (50% beta-TCP with 50% PCL) and 70TCP30PCL (70% beta-TCP with 30% PCL) composite scaffolds for bone tissue engineering. The 70TCP30PCL scaffold containing the highest beta-TCP content exhibited rougher morphologies and more porous than the other scaffolds (i.e., PCL and 50TCP50PCL). In vitro studies revealed that cell proliferation and alkaline phosphate activity were improved on the beta-TCP-based composite scaffolds. Our results suggest that our 3-D printed beta-TCP-containing PCL scaffolds would benefit new dental applications or regeneration therapies. (C) 2016 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.</P>