• Title/Summary/Keyword: enzymatic analysis

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Comparison of Differential Scanning Calorimetry with Enzymatic Method for the Determination of Gelatinization Degree of Corn Starch (DSC에 의한 전분의 Endothermic peak와 효소분석법에 의한 호화도 비교)

  • Lee, Boo-Yong;Mok, Chul-Kyoon;Lee, Cherl-Ho
    • Korean Journal of Food Science and Technology
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    • v.25 no.4
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    • pp.400-403
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    • 1993
  • Gelatinization degrees of torn and waxy corn starches in the low-moisture environment were determined by DSC thermogram and enzymatic analysis, the results were compared each other As the moisture content increased from 20% to 70%, the enthalpy of endothermic peak of starch increased linearly in DSC thermograms. When the moisture content exceeded above 70%, the DSC enthalpy of starch remained constant in DSC thermogram. The enthalpies for gelatinization of corn and waxy corn starches were 3.23 cal/g and 4.2 cal/g, respectively. When gelatinization degrees of starches were measured by enzymatic analysis, the gelatinization degree increased linearly as the moisture content increased from 20% to 80%. A linear correlation between DSC and enzymatic analysis was obtained only when the moisture content was under 70%.

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Analytical Studies of $H_2O_2$-Producing Oxidase Systems ($H_2O_2$-생성 산화효소계에 관한 분석 연구)

  • Younghee Hahn;Hae-Lim Cho
    • Journal of the Korean Chemical Society
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    • v.37 no.10
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    • pp.874-880
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    • 1993
  • Spectrophotometric enzymatic analysis and amperometric enzymatic analysis for the determinations of glucose and ethanol were studied utilizing glucose oxidase (GO) and alcohol oxidase (AO), respectively, which commonly consume $O_2$ and produce $H_2O_2$. For the determination of glucose, $H_2O_2$ were coupled to $K_4Fe(CN)_6$ via peroxidase producing $K_3Fe(CN)_6$ whose absorbance was measured at 418 nm or whose diffusion current was measured on the glassy carbon electrode at an applied potential of -55 mV vs. Ag/AgCl (sat. KCl) reference electrode. Amperometric analysis was 1000 times more sensitive as well as 10 times better in the linear concentration range than spectrophotometric analysis. For the determination of ethanol, AO only was used for the enzymatic analysis, since $K_3Fe(CN)_6$ was completely disappeared as soon as AO was added. Either rate of $H_2O_2$ produced was amperometrically measured at +0.900 V or rate of $O_2$ consumed was measured at -0.500 V vs. Ag/AgCl(sat. KCl) reference electrode.

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Metabolism of Dimethylphthalate by Aspergillus niger

  • Pradeepkmar;Sharanagouda;Karegoudar, T.B.
    • Journal of Microbiology and Biotechnology
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    • v.10 no.4
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    • pp.518-521
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    • 2000
  • Aspergillus niger is capable of metabolizing dimethyphthalate. The maximum weight of mycelium wa observed afterabout 6-8 dys of incubation. A TLC analysis revealed the accumulation of metabolites in the resting cell culture. Monomethylphthalate, phthalate, and protocatechuate were shown to be the intermediates by thin layer chromatographic and spectrophotometric analyses. The fungus metabolized dimethylphthalate through monomethylphthalate, phthalate, and protocatechuate as evidenced by the oxygen uptake and an enzymatic analysis. The terminal aromatic metabolite, protocatechuate, is metabolized via the ortho-cleavage pathway.

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Co-expression of Gamma-Aminobutyrate Aminotransferase and Succinic Semialdehyde Dehydrogenase Genes for the Enzymatic Analysis of Gamma-Aminobutyric Acid in Escherichia Coli

  • So, Jai-Hyun;Lim, Yu-Mi;Kim, Sang-Jun;Kim, Hyun-Ho;Rhee, In-Koo
    • Journal of Applied Biological Chemistry
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    • v.56 no.2
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    • pp.89-93
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    • 2013
  • Gamma-aminobutyric acid (GABA) aminotransferase (gabT) and succinic semialdehyde dehydrogenase (gabD) genes from Pseudomonas fluorescens KCCM 12537 were cloned into a single pETDuet-1 vector and co-expressed in Escherichia coli BL21(DE3) simultaneously. The mixture of both enzymes, called GABase, is the key enzyme for the enzymatic analysis of GABA. The molecular mass of the GABA aminotransferase and succinic semialdehyde dehydrogenase were determined to be 52.8 and 46.7 kDa following computations performed with the pI/Mw program, respectively. The GABase activity between pH 6.0 and 9.0 for 24 h at $4^{\circ}C$ remained over 75%, but under pH 6.0 decreased rapidly. The GABase activity between 25 and $35^{\circ}C$ by the treatment at pH 8.6 for 30 min remained over 80%, but over $35^{\circ}C$ decreased rapidly. When the activity against GABA was defined as 100%, the purified GABase activity against 5-aminovaleric acid having a similar structure to GABA showed 47.7% and GABase activity against ${\beta}$-alanine, ${\varepsilon}$-amino-n-caproic acid, $_L$-ornithine, $_L$-lysine, and $_L$-aspartic acid showed between 0.3 to 2.3%. The GABA content was analyzed with this co-expressed GABase, compared with the other GABase which was available commercially. As a result, the content of GABA extracted from brown rice, dark brown rice, and black rice were $26.4{\pm}3.5$, $40.5{\pm}4.7$ and $94.7{\pm}9.3{\mu}g/g$, which were similar data of other GABase in the error ranges.

Effect of 13-cis-Retinoic Acid and Ginseng Saponin on Hyperkeratinization of Guinea Pig Skin

  • KIm, Hye-Young;Jin, Sung-Ha;Kim, Shin-Il
    • Journal of Ginseng Research
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    • v.13 no.2
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    • pp.248-253
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    • 1989
  • The effects of 13-cis-retinoic acid and ginseng saponin iron Korean red ginseng on hyperkeratinization of guinea pig skin were investigated by means of enzymatic analysis and light microscopic observation. To induce hyperkeratinization, hexadevance It was topically applied to the dorsal skin of female guinea Pigs every other day for eight days and 13-cis- retinoic acid or ginseng saponin solution was administered orally or topically applied daily during the experimental period. As a result, both topical application of ginseng saponin and oral administration of 13-cis-retinoic acid showed prepentive effects on hyperkeratinization while topical application of 13-cis-retinoic acid inhibited normal epidermal cell proliferation and reduced epidermal enzyme activities such as LDH. ICD and GSPDH below the levels in a normal epidermis. It is suggested that topical application of ginseng saponin and oral administration of 13-cis-retinoic acid may have beneficial efforts against hyperkeratinization possibly by controlling epidermal proliferation and enzyme activities related to epidermal energy metabolism.

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Mammalian Sialyltransferase Superfamily : Structure and Function

  • Lee, Young-Choon
    • Proceedings of the Korean Society of Life Science Conference
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    • pp.13-19
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    • 2002
  • To elucidate the regulatory mechanism for expression of sialyl-glycoconjugates and their biological functions, ninetheen sialyltransferase cDNAs including eleven by our group or co-works have been cloned and characterized so far. The cloned sialyltransferases are classified into four families according to the carbohydrate linkages they synthesize: ${\alpha}2,3-sialyltransferase$ (ST3Gal I-VI), ${\alpha}$ 2,6-sialyltransferase (ST6Gal I), GalNAc ${\alpha}$ 2,6-sialyltransferase (ST6GalNAc I-VI), and ${\alpha}2,8-sialyltransferase$ (ST8Sia I-VI). Each of the sialyltransferase genes is differentially expressed in a tissue-, cell type-, and stage-specific manner. These enzymes differ in their substrate specificity and various biochemical parameters. However, enzymatic analysis conducted in vitro with recombinant enzyme revealed that one linkage can be synthesized by multiple enzymes. We present here an overview of structure and function of sialyltransferases performed by our group and co-works. Genomic structures and transcriptional regulation of two kinds of human sialyltransferase gene are also presented.

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Kinetic Approaches to Measuring Peroxiredoxin Reactivity

  • Winterbourn, Christine C.;Peskin, Alexander V.
    • Molecules and Cells
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    • v.39 no.1
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    • pp.26-30
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    • 2016
  • Peroxiredoxins are ubiquitous thiol proteins that catalyse the breakdown of peroxides and regulate redox activity in the cell. Kinetic analysis of their reactions is required in order to identify substrate preferences, to understand how molecular structure affects activity and to establish their physiological functions. Various approaches can be taken, including the measurement of rates of individual steps in the reaction pathway by stopped flow or competitive kinetics, classical enzymatic analysis and measurement of peroxidase activity. Each methodology has its strengths and they can often give complementary information. However, it is important to understand the experimental conditions of the assay so as to interpret correctly what parameter is being measured. This brief review discusses different kinetic approaches and the information that can be obtained from them.

Engineering Recombinant Streptomyces coelicolor Malate Synthase with Improved Thermal Properties by Directed Mutagenesis

  • Koh, Ro-Sita;Goh, Liuh-Ling;Sim, Tiow-Suan
    • Journal of Microbiology and Biotechnology
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    • v.14 no.3
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    • pp.547-552
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    • 2004
  • Streptomyces thermovulgans malate synthase (stMS) is known to be more thermostable and thermoactive than S. coelicolor malate synthase (scMS). Therefore, based on the amino acid sequence of stMS, 3 scMS mutants, namely P186R, T8PL9P, and T8PL9PP186R, were created by site-directed mutagenesis in an attempt to engineer a more thermoactive and thermostable enzyme. An enzymatic analysis of the wild-type and mutant MS revealed that P186R and T8PL9PP186R were more thermoactive than the wild-type scMS and T8PL9P. Furthermore, all 3 mutants exhibited a greater thermo stability than scMS, thereby suggesting that both R186 and P8P9 can cause increased thermo stability in scMS.

Expression and Characterization of Truncated Recombinant Human Cytochrome P450 2J2

  • Park, Hyoung-Goo;Lim, Young-Ran;Han, Songhee;Kim, Donghak
    • Toxicological Research
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    • v.30 no.1
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    • pp.33-38
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    • 2014
  • The human cytochrome P450 2J2 catalyzes an epoxygenase reaction to oxidize various fatty acids including arachidonic acid. In this study, three recombinant enzyme constructs of P450 2J2 were heterologously expressed in Escherichia coli and their P450 proteins were successfully purified using a $Ni^{2+}$-NTA affinity column. Deletion of 34 amino acid residues in N-terminus of P450 2J2 enzyme (2J2-D) produced the soluble enzyme located in the cytosolic fraction. The enzymatic analysis of this truncated protein indicated the typical spectral characteristics and functional properties of P450 2J2 enzyme. P450 2J2-D enzymes from soluble fraction catalyzed the oxidation reaction of terfenadine to the hydroxylated product. However, P450 2J2-D enzymes from membrane fraction did not support the P450 oxidation reaction although it displayed the characteristic CO-binding spectrum of P450. Our finding of these features in the N-terminal modified P450 2J2 enzyme could help understand the biological functions and the metabolic roles of P450 2J2 enzyme and make the crystallographic analysis of the P450 2J2 structure feasible for future studies.

A Study on Sugars in Korean Sweet Rice Drink "Sikhye"(II) -Enzymatic Analysis of Isomaltooligosaccharides and Rice Residue- (식혜의 이소말토올리고당에 관한 연구(II) -효소적 분석-)

  • 안용근
    • The Korean Journal of Food And Nutrition
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    • v.10 no.1
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    • pp.87-91
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    • 1997
  • Isomaltooligosaccharides in Sikhye were digested with enzyme (30unit/ml) of $\alpha$-amylase, $\alpha$-glucosidase and glucoamylase from Aspergillus awamori, sweet potato $\beta$-amylase and human salivary $\alpha$-amylase at 37$^{\circ}C$ for 1 hour, respectively. These amylases acted on these saccharides to give hydrolysis products with less than 20% of degree of hydrolysis, except the case of glucoamylase with 62% of high degree of hydrolysis. $\alpha$-Glucosidase plus human salivary $\alpha$-amylase hydrolyzed it to attain the hydrolysis value up to 25%, but further increment of hydrolysis was not observed. Rice residue in Sikhye has similar sugar composition and structure, judging from sugar analyses by the enzymatic hydrolysis. These results suggest that isomaltooligosaccharides and rice residue in Sikhye can be a growth factor for Bifidobacterium and dietary fiber which is useful for human health.

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